DRAFT PROPOSAL
EPA-402R-10003
FEDERAL GUIDANCE REPORT NO. 14
Radiation Protection Guidance for Diagnostic and Interventional X-Ray Procedures
Interagency Working Group on Medical Radiation
U.S. Environmental Protection Agency
Washington, D.C. 20460
DRAFT PROPOSAL
2012
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2 PREFACE
3
4 This document is Federal Guidance Report No. 14 (FGR 14), "Radiation Protection Guidance for
5 Diagnostic and Interventional X-ray Procedures." It replaces Federal Guidance Report No. 9
6 (FGR 9) (EPA 1976), "Radiation Protection Guidance for Diagnostic X-rays," which was
7 released in October 1976. Federal Guidance reports were initiated under the Federal Radiation
8 Council (FRC), which was formed in 1959, through Executive Order 10831. A decade later its
9 functions were transferred to the Administrator of the newly formed Environmental Protection
10 Agency (EPA) as part of Reorganization Plan No. 3 of 1970 (Dunn et al. 2012). Under these
11 authorities it is the responsibility of the Administrator to "advise the President with respect to
12 radiation matters, directly or indirectly affecting health, including guidance for all Federal
13 agencies in the formulation of radiation standards and in the establishment and execution of
14 programs of cooperation with States." (EPA 2012)
15
16 FGR 9 provided constructive guidance on the use of diagnostic film radiography, for which there
17 was an incentive to deliver appropriate radiation doses and avoid retakes resulting from under- or
18 over-exposing the film. This report, Federal Guidance Report No. 14, focuses on the transition
19 to digital imaging, extends the scope (to include computed tomography (CT), interventional
20 fluoroscopy, bone densitometry, and veterinary practice), and updates sections on radiology and
21 dentistry that were covered in FGR 9. It also addresses adequate imaging through justification of
22 the procedure and optimization, and features an expanded section on occupational exposure.
23
24 FGR 9 was developed out of a growing concern in the 1970s among medical practitioners,
25 medical physicists, and other scientists that medical uses of ionizing radiation represented a
26 significant and growing source of exposure for the U.S. population. Human exposures to
27 medical radiation were neither controlled by law nor covered by consensus guidance. In 1972,
28 the Federal Radiation Council released a report concluding that "...medical diagnostic radiology
29 accounts for at least 90% of the total man-made radiation dose to which the U S. population is
30 exposed." In response, the Environmental Protection Agency (EPA) and the Department of
31 Health, Education, and Welfare (predecessor of the Department of Health and Human Services
32 (DHHS)) developed and issued FGR 9, which was approved by President Carter (Carter 1978)
33 and published in the Federal Register on February 1, 1978.
34
35 According to EPA (Carter 1980), FGR 9 was the first Federal Guidance Report to provide a
36 framework for developing radiation protection programs for diagnostic uses of x-rays in
37 medicine. It introduced into Federal guidance the concepts of:
38 • Conducting medical x-ray studies only to obtain diagnostic information,
39 • Limiting routine or elective screening examinations to those with demonstrated benefit
40 over risk,
41 • Considering possible fetal exposures during examinations of pregnant or potentially
42 pregnant patients,
43 • Ensuring diagnostic equipment operators meet or exceed the standards of credentialing
44 organizations, and
45 • Specifying that standard x-ray examinations should satisfy maximum numerical exposure
46 criteria.
47
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48 Much of FGR 9 has stood the test of time, but other parts have become obsolete. In particular,
49 the advent of digital x-ray image acquisition has eliminated film blackening as a built-in
50 deterrent to over-exposing patients.
51
52 Digital imaging methodologies have improved medical care by increasing the quality of
53 diagnostic images and significantly decreasing the need for exploratory surgeries. However, in
54 some cases, the use of this newer technology was accompanied by a significant increase in
55 patient radiation dose (Seibert et al. 1996). Some newly introduced technologies, e.g., CT,
56 yielded higher patient doses than the radiographic procedures they replaced. Finally, increased
57 utilization of imaging studies resulted in a greater radiation dose to the population.
58
59 The U.S. Food and Drug Administration's (FDA) performance standards for radiation emitting
60 products address radiography, fluoroscopy, and CT equipment, and are codified at 21 CFR Part
61 1020 (FDA 2012e). The FDA revised these performance standards in 2005, in part to address
62 some of the radiation dose issues.
63
64 The National Council on Radiation Protection and Measurements (NCRP) reports that medical
65 radiation exposure to the average member of the US population has increased rapidly and
66 continues to do so. Their previous estimate, based on 1970's and early 1980's data, was that
67 medical exposure accounted for 0.53 millisievert (mSv) or 53 millirem (mrem) per year, which
68 was 15% of the total annual average (per capita) dose (NCRP 1989a). Based on 2006 data, this
69 estimate was increased to 3 mSv (300 mrem) per year or 48% of the total (NCRP 2009).
70
71 Concerns continue to be raised about the risks associated with patients' exposure to radiation
72 from medical imaging (Amis et al. 2007; FDA 2010b; FDA 2012e). Because ionizing radiation
73 can cause damage to DNA, exposure may increase a person's lifetime risk of developing cancer.
74 Although the risk to an individual from a single exam may not itself be large, millions of exams
75 are performed each year, making radiation exposure from medical imaging an important public
76 health issue (Brenner 2007). Berrington de Gonzalez et al. estimate that approximately 29,000
77 future cancers could be due to CT scans performed in the U.S. in 2007 (Berrington de Gonzalez
78 et al. 2009). Smith-Bindman et al. estimate that 1 in 270 women and 1 in 600 men who undergo
79 CT coronary angiography at age 40 will develop cancer from that CT scan; the risks for 20-year-
80 olds are estimated to be roughly twice as large, and those for 60-year-olds are estimated to be
81 roughly half as large (Smith-Bindman et al. 2009). Although experts may disagree on the extent
82 of the risk of cancer from medical imaging, there is uniform agreement that care should be taken
83 to weigh the medical necessity of a given level of radiation exposure against the risks.
84
85 Given these changes in the available technologies, the reported increase in annual dose from
86 medical imaging, and concerns addressed above, EPA has decided to issue this new guidance to
87 the Federal medical community. Also, it is suitable for use by the broader medical community.
88 This guidance creates no binding legal obligation; rather, it offers recommendations for the safe
89 and effective use of x-ray imaging modalities. Federal agencies that adopt these
90 recommendations (e.g., into orders or standard operating procedures) should, at their discretion,
91 strengthen these statements where appropriate. EPA believes that the information contained in
92 this guidance will help users of diagnostic imaging equipment ensure that any given procedure is
93 justified for the patient being examined and that the dose delivered to that patient is optimized.
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94 EPA also believes that the information contained in this guidance will provide for radiation
95 protection of medical workers. The goal of radiation management is to keep patient and worker
96 radiation doses as low as reasonably achievable consistent with the use of appropriate equipment
97 and the imaging requirements for specific patients and specific procedures.
98
99 FGR 14 establishes guidance for digital x-ray imaging that addresses protection aspects that were
100 not envisioned in FGR 9. These include:
101 • Reference levels and dose optimization
102 • Newer dose metrics
103 • Introduction of positron emission tomography/computed tomography (PET/CT)
104 • Computed tomography (CT), fluoroscopy (including interventional fluoroscopy), bone
105 densitometry, and veterinary imaging as modalities additional to radiography and
106 dentistry
107
108 In carrying out its federal guidance responsibilities, EPA works closely with other federal
109 agencies through its participation on the Interagency Steering Committee on Radiation Standards
110 (ISCORS). Moreover, EPA recognizes, as it did in 1976, that the expertise needed to make
111 sound recommendations for reducing unnecessary radiation exposure due to the medical use of
112 x-rays in diagnostic and interventional procedures resides in several agencies. Therefore, this
113 report was prepared by the interagency Medical Work Group of the ISCORS Federal Guidance
114 Subcommittee that included physicians, medical physicists, health physicists, and other scientists
115 and health professionals from the Department of Defense, the Department of Veterans Affairs,
116 the Department of Health and Human Services, the Department of Labor, and the EPA.
117
118 As in FGR 9, the recommendations contained in this report represent consensus judgment of the
119 Medical Work Group for the practice of diagnostic and interventional imaging by Federal
120 agencies. Since the body of knowledge on both the radiation exposure and efficacy of x-ray
121 examinations is rapidly changing, comments and suggestions on the areas addressed by this
122 report will assist EPA to conduct periodic reviews and to make appropriate revisions.
123
124
125
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129
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13 0 RECOMMENDATIONS FOR AGENCY ACTIONS
131
132 1. Patient safety requires that infrastructure exists for collecting, storing, and analyzing patient
133 dosimetry data. Federal facilities should plan for longitudinal tracking of patient radiation
134 doses. This planning should address the data acquisition, networking, storage, analysis, and
135 security requirements of existing and planned future diagnostic devices.
136 2. All uses of radiation in diagnostic medical imaging should be justified and optimized. This
137 is the responsibility of all involved providers and technologists. Dose management begins
138 when a patient is considered for a procedure involving ionizing radiation, involves
139 equipment setup before the exam begins, and ends when any necessary radiation-related
140 follow-up is completed.
141 3. It is strongly recommended that the justification of medical exposure for an individual
142 patient be carried out by the Referring Medical Practitioner, in consultation with the
143 Radiological Medical Practitioner when appropriate. Each health care facility should
144 establish a formal mechanism whereby Referring Medical Practitioners have sources of
145 information available at the time of ordering regarding appropriate diagnostic imaging
146 methods to answer the clinical question and to optimize ionizing radiation dose to the
147 patient.
148 4. For each type of examination, Federal facilities and agencies should promote the
149 development of national reference levels for use as quality assurance and quality
150 improvement tool s.
151 5. For each type of examination there exists, within available technology, an optimal
152 combination of imaging equipment and technique factors to produce adequate images at
153 doses below the reference level. Federal facilities should evaluate each imaging system's
154 performance to optimize dose, and maintain this by establishing appropriate procedures and
155 conducting periodic monitoring.
156 6. Agencies should only adopt screening programs that have been submitted to rigorous
157 scientific evaluation of efficacy, as has been done for mammography, to ensure that the risk
158 posed to the population screened does not outweigh the benefits in detection of disease.
159 7. Agencies should use methods for estimating individual occupational doses based on the
160 goal of assigning accurate doses rather than overly conservative estimates of doses. NCRP
161 Report No. 122 provides recommended methods for determining effective dose (E) and
162 effective dose equivalent. The various Federal regulatory agencies should establish
163 consistent methods and procedures for this purpose.
IV
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DRAFT PROPOSAL
164 TABLE OF CONTENTS
165
166 PREFACE I
167 RECOMMENDATIONS FOR AGENCY ACTIONS IV
168 TABLES IX
169 INTERAGENCY WORKING GROUP ON MEDICAL RADIATION X
170 INTRODUCTION 1
171 RADIATION SAFETY STANDARDS AND GENERAL CONCERNS 4
172 GENERAL PRINCIPLES OF RADIATION PROTECTION 4
173 GENERAL STANDARDS FOR PROTECTION AGAINST RADIATION 6
174 Minors as Workers 6
175 Embryo or Fetus of Pregnant Workers 6
176 Members of the Public 7
177 GENERAL CONCEPTS FOR RADIATION PROTECTION 7
178 RADIATION SAFETY PROGRAM 8
179 Radiation Safety Officer 8
180 Qualified Physicist 9
181 Personnel and Area Monitoring 9
182 Patient Safety 10
183 Radiation Safety Procedures for Fluoroscopy 10
184 Special Patient Populations 11
185 Pregnant patients 11
186 Pediatric patients 12
187 Patients enrolled in a research protocol 12
188 Analysis of Risk from Radiation 13
189 Informed Consent for Research Involving Radiation 14
190 Occupational Radiation Safety Training 14
191 Notification and Reporting Requirements 14
192 STRUCTURAL SHIELDING AND DOOR INTERLOCK SWITCHES 15
193 REQUESTING AND PERFORMING STUDIES INVOLVING X-RAYS 15
194 REQUESTING STUDIES: REFERRING MEDICAL PRACTITIONERS (REQUESTING HEALTH
195 PROFESSIONALS) 15
196 Qualifications to Request X-ray Examinations 17
197 PERFORMING AND SUPERVISING STUDIES: RADIOLOGICAL MEDICAL PRACTITIONERS AND
198 TECHNOLOGISTS 17
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199 Radiological Medical Practitioners 18
200 Radiologists 18
201 Medical Radiologic Technologists 19
202 SCREENING AND ADMINISTRATIVE PROGRAMS 19
203 Chest Radiography 20
204 Mammography 20
205 REFERRAL AND SELF-REFERRAL EXAMINATIONS 20
206 Patients Requesting Imaging on Themselves without a Referral from a Licensed Independent Practitioner
207 (Referring Medical Practitioner) 20
208 Physician Self-Referral 20
209 COMMUNICATION AMONG PRACTITIONERS 21
210 TECHNICAL QUALITY ASSURANCE IN MEDICAL IMAGING WITH X-RAYS 23
211 TECHNIQUE FACTORS 23
212 TESTING BY A QUALIFIED PHYSICIST 24
213 EQUIPMENT FAILURE 25
214 DEFICIENCY CORRECTION VERIFICATION 25
215 DOSIMETRY 25
216 REFERENCE LEVELS 26
217 GUIDANCE BY DIAGNOSTIC AND INTERVENTIONAL MODALITY 28
218 INTRODUCTION 28
219 RADIOGRAPHY 30
220 Equipment 30
221 Testing and Quality Assurance 31
222 Personnel 32
223 Radiological Medical Practitioner 32
224 Technologist 32
225 Other personnel 33
226 Procedures 33
227 FLUOROSCOPY 37
228 Equipment 37
229 Testing and Quality Assurance 40
230 Personnel 40
231 Procedures 42
232 Dose measurement 42
23 3 Recordkeeping 42
234 Patient management 43
235 Quality process 44
236 Staff safety 46
237 COMPUTED TOMOGRAPHY 47
238 Equipment 48
239 Testing and Quality Assurance 49
VI
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240 Personnel 49
241 Procedures 49
242 BONE DENSITOMETRY 52
243 Equipment 52
244 Testing and Quality Assurance 53
245 Personnel 55
246 Procedures 56
247 DENTAL 58
248 Equipment 58
249 Testing and Quality Assurance 60
250 Personnel 61
251 Procedures 62
252 VETERINARY 64
253 Equipment 64
254 Testing and Quality Assurance 65
255 Personnel 66
256 Procedures 66
257 Veterinary clinic setup 66
258 Personal protective equipment 67
259 Animal restraint 67
260 Use of x-ray equipment 67
261 Personal dosimetry 68
262 Special procedures for portable hand-held systems 68
263 MEDICAL IMAGING INFORMATICS 69
264 SUMMARY AND RECOMMENDATIONS FOR FACILITY ACTION 71
265 GENERAL 71
266 BONE DENSITOMETRY 71
267 CHILDREN AND PREGNANT WOMEN 72
268 DENTISTRY 72
269 FLUOROSCOPY 72
270 VETERINARY 73
271 INFORMATICS 73
272 INFORMED CONSENT 73
273 PRESCRIPTION 73
274 REFERENCE LEVELS 74
275 ACRONYMS AND ABBREVIATIONS 75
276 GLOSSARY 78
VII
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277 APPENDIX A - NIH INFORMED CONSENT TEMPLATES A-l
278 MINIMAL RISK A-2
279 MINOR TO INTERMEDIATE RISK A-3
280 REFERENCES REF-1
281
282
VIII
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DRAFT PROPOSAL
283 TABLES
284
285 Table 1. Testing Frequency of Imaging Equipment that Produces X-Rays 24
286 Table 2. Quality Assurance Measures for Film and Digital Modalities 34
287
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DRAFT PROPOSAL
INTERAGENCY WORKING GROUP ON MEDICAL RADIATION
292
340
Department of Health and Human Services 341
L. Samuel Keith, MS, CHP, CO-CHAIR 342
John L. McCrohan, MS (retired)
Donald L. Miller, MD, FSIR FACR
Petro Shandruk (retired)
Department of the Air Force
Cindy L. Elmore, Ph.D., DABR
LTC Scott Nemmers, BSC
Department of the Army
COL Mark W. Bower, CHP, Ph.D.
COL Erik H. Torring, DVM, MPH
343
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353
354
Department of Labor, 355
Occupational Safety and Health Administra36&
Doreen G. Hill, MPH, Ph.D. 357
358
Department of the Navy 359
CAPT Stephen T. Sears, MC, CO-CHAIR 360
CAPT Michael A. Ferguson, MC
CDR Douglas W. Fletcher, MSC
CDR Chad A. Mitchell, MSC
Department of Veterans Affairs
Ronald C. Hamdy, MD, FRCP, FACP
Edwin M. Leidholdt, Jr., Ph.D.
Eleonore D. Paunovich, DOS, MS
361
362
363
364
365
366
367
368
369
370
Environmental Protection Agency
Michael A. Boyd, MSPH
Commonwealth of Pennsylvania
John P. Winston
Expert Consultants/Other Contributor?,
Kimberly Applegate, MD, MS, FACR
Charles E. Chambers, MD, FACC FSCAI
Steven Don, MD
Marilyn Goske, MD
Fred A. Mettler, MD, MPH, FACR
Terrence J. O'Neil, MD, FACP
S. Jeff Shepard, MS
Dana M. Sullivan, RT(R)(M) , DVA
Acknowledgements
Environmental Protection Agency
Helen Burnett (retired)
Jessica Wieder
Department of Health and Human Services
J. Nadine Gracia, MD
Sandra Howard
X
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DRAFT PROPOSAL
371 INTRODUCTION
372
373 There are a few commonalities that are integrated throughout this document.
374
375 1. This guidance was written without regard to specific models of equipment
376 2. It is intended to be a practical and appropriately prescriptive tool.
377 3. A balance was struck between being sufficiently specific and keeping the document generic
378 enough to remain current.
379 4. Dose reduction has been offset by increased utilization (number and type of procedures)
380 5. Dose reduction technology should be incorporated into the equipment.
381 6. Dose reduction technology only works when it is used.
382 7. Operators need initial and periodic refresher training, easy to use tools (e.g., checklists),
383 and motivation.
384 8. Dose reduction strategies should be integrated into protocols, where possible.
385 9. Improvements in imaging and equipment will continue.
386
387 The fundamental objective in performing an x-ray examination is to obtain the required
388 diagnostic information with only as much radiation dose as is required to achieve adequate image
389 quality. Achievement of this objective requires: 1) assuring equipment is functioning properly
390 and calibrated, 2) assuring equipment is operated only by competent personnel, 3) appropriately
391 preparing the patient, and 4) selecting appropriate equipment and using appropriate protocols.
392
393 Even more so than when the original FGR 9 (EPA 1976) was published in 1976, imaging in 2012
394 plays a critical role in medical care within the United States. In the approximately thirty years
395 that have elapsed since the early 1980s, medical imaging has grown rapidly in utilization and
396 capability (NCRP 1989a; NCRP 2009). Computed tomography (CT) provided a new cross
397 sectional imaging method, initially for evaluating the contents of the skull and then for other
398 body cavities and organs, for assessing tissues and organs that previously required surgery for
399 evaluation. This resulted in fewer exploratory surgical procedures and permitted more accurate,
400 non-invasive diagnoses. The number of CT procedures is growing at a rate greater than 10% per
401 year.
402
403 Smaller image detector elements increased the spatial resolution of CT imaging. Other
404 technological improvements have included improved mechanical function, multi-row detector
405 CT scanners, more capable computer technology, and improved x-ray tubes. As a result CT now
406 permits evaluation of physiologic characteristics as well as anatomy, and permits pediatric exams
407 previously limited by motion artifact. Indications for imaging have increased as have use of
408 multi-sequence studies that allow organs to be evaluated during several phases of contrast
409 enhancement.
410
411 Improvements in fluoroscopy detector systems and improvements in techniques and equipment
412 (catheters, stents, embolic agents) facilitated an increase in the number and variety of image-
413 guided interventions. These procedures replaced many open surgical procedures and now
414 provide new therapy options for many diseases.
415
416 With the vast information available through imaging and the increased availability of CT and
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DRAFT PROPOSAL
417 fluoroscopy systems, there has been a marked increase in the contribution of radiation dose from
418 x-ray based medical studies to the overall radiation dose to the US population. CT imaging
419 studies increased from 3 million in 1980 to 62 million in 2006, at which time, scans were
420 increasing at the rate of 10% per year (ACR 2007d; NCRP 2009). During this period, the
421 estimated effective dose from all x-ray-related medical procedures other than radiation therapy
422 increased from 0.39 to 2.23 millisievert per year (mSv/y) (39 to 223 millirem per year (mrem/y)),
423 or from 11% to 36% of the total US population dose. By 2006, the annual x-ray effective dose in
424 the U S. virtually equaled that from radon as well as the worldwide collective dose resulting
425 from the Chernobyl disaster (ACR 2007d; NCRP 2009).
426
427 Human epidemiological studies have demonstrated the potential of ionizing radiation to induce
428 cancer at an effective dose greater than 0.1 Sv. It is prudent to consider that lower doses might
429 also carry a risk. National and international organizations have classified ionizing radiation
430 (including x-rays) as a known human carcinogen (NTP 2011). These groups include the
431 National Toxicology Program and the World Health Organization's International Agency for
432 Research on Cancer (IARC 2012).
433
434 Technological advances have improved diagnostic capabilities and image quality. Some of these
435 advances entail increases in patient dose. However, some have provided new and effective
436 methods for reduction of radiation exposure. Improvements in film and film-screen technology
437 permitted reduction in the amount of radiation dose necessary to obtain standard images like the
438 chest radiograph. Improvement in image intensifiers and digital image receptors decreased the
439 amount of radiation necessary for fluoroscopic studies and the advent of pulsed fluoroscopy
440 permits even further reduction in the radiation required for a given imaging study. Simple
441 advances such as "last image hold" that cause the last image acquired to remain on the video
442 display screen after the fluoroscopy is stopped markedly reduce the dose of radiation involved in
443 these studies. Transition to improved systems also markedly reduced the radiation dose
444 necessary for mammography. In CT, improvements in detector composition and function, dose
445 modulation based on the patient's size and body part examined, advanced reconstruction
446 algorithms, and prospective acquisition gating during the cardiac cycle have all provided
447 methods to significantly reduce the radiation dose from imaging studies.
448
449 Research has demonstrated that these dose-reduction techniques are not always employed or
450 used to best advantage in medical imaging, and medical education does not typically provide
451 focus on the effects of and protection from radiation exposure (ICRP 2000b). Seemingly simple
452 and obvious items, like altering the energy and amount of radiation used in imaging children as
453 compared with adults, have not been adopted universally. Some units with pulsed fluoroscopy
454 capability have never been used in that mode. This document is intended to assist the reader in
455 appreciating the need for understanding doses from procedures and maximizing the benefit-risk
456 ratio in the use of medical imaging systems.
457
458 The primary goal of medical imaging is to answer a clinical question or guide an intervention.
459 When performing medical imaging with ionizing radiation, using only as much radiation dose as
460 is required to achieve adequate image quality should be the second goal. There are several ways
461 to reduce radiation dose that will be discussed specifically in the sections dedicated to each
462 imaging modality.
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463
464 Important ways to reduce radiation exposure to patients are to avoid duplicate studies and to
465 avoid any study that does not contribute effectively to the primary goal of answering the clinical
466 question. Sharing digital images among facilities reduces patient radiation doses by precluding
467 unnecessary duplicative imaging. The individual requesting the imaging examination should
468 have sufficient knowledge of the radiation doses associated with imaging examinations to be
469 able to request the most effective imaging study that provides the necessary information at the
470 lowest radiation dose. When appropriate, examinations not involving ionizing radiation are
471 preferable. Organizations, such as the American College of Radiology (ACR) and American
472 College of Cardiology (ACC), have published guidance that can help health professionals choose
473 the most appropriate examinations to answer their clinical questions.
474
475 As an example, in the evaluation of a patient with cough and fever, a standard two view chest x-
476 ray series may provide adequate information for the diagnosis and treatment of pneumonia at a
477 small fraction of the radiation dose that would be delivered by a chest CT. Similarly, a CT
478 angiogram may provide visualization of a large vascular distribution in a single imaging run with
479 a lower radiation dose than the multiple digital subtraction angiographic sequences that may be
480 required to adequately visualize the same area.
481
482 Once a specific imaging study is selected, technical aspects of the image acquisition become the
483 most critical influence on radiation dose delivered to the patient and quality of the resulting
484 images. Although reduction of radiation exposure overall should be a goal, reduction of dose to
485 a level that results in an increased number of unsatisfactory examinations requiring repeat
486 imaging will actually increase patient dose overall and should be avoided as much as excessive
487 dose should be. In the use of film-screen technology, over and under exposure were evident on
488 the resulting image, but with digital based imaging, these conditions are not as apparent. One
489 reason is that image quality may continue improving with increasing dose, even beyond what is
490 needed or adequate. As a result, good clinical practices include effective quality control
491 programs, optimized imaging protocols providing only the necessary sequences, adjustment of
492 technical factors and dose of radiation for patient size and age, and employment of the best
493 available dose reduction technologies existing in the equipment in use.
494
495 This document is intended to assist the reader in validating their efforts and maximizing the
496 benefitrisk ratio in requesting and performing medical diagnostic and interventional procedures
497 involving x-rays. The document is divided into sections based on imaging modality.
498
499
500
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501 RADIATION SAFETY STANDARDS AND GENERAL CONCERNS
502
503 GENERAL PRINCIPLES OF RADIATION PROTECTION
504
505 The International Commission on Radiological Protection (ICRP) has formulated a set of three
506 fundamental principles for radiation protection (ICRP 2007a; ICRP 2007c). These principles are
507 justification., optimization of protection., and application of dose limits. The first two principles
508 apply to a source of exposure, and thus are intended to support protection for all individuals who
509 may be exposed to that source. The third principle applies to occupational and public exposure,
510 but explicitly excludes medical exposure of patients.
511
512 The principle of'justification states that, in general, "any decision that alters the radiation
513 exposure situation should do more good than harm. This means that by introducing a new
514 radiation source, by reducing existing exposure, or by reducing the risk of potential exposure,
515 one should achieve sufficient individual or societal benefit to offset the detriment it causes"
516 (ICRP 2007a; ICRP 2007c). With regard to medical exposures specifically, "the principal aim of
517 medical exposures is to do more good than harm to the patient, subsidiary account being taken of
518 the radiation detriment from the exposure of the radiological staff and of other individuals"
519 (ICRP2007a).
520
521 The ICRP (ICRP 2007a) addresses justification in medicine as follows:
522
523 "The principle of justification applies at three levels in the use of radiation in medicine.
524 At the first level, the use of radiation in medicine is accepted as doing more good than
525 harm to the patient. This level of justification can now be taken for granted.
526
527 "At the second level, a specified procedure with a specified objective is defined and
528 justified (e.g., chest radiographs for patients showing relevant symptoms, or a group of
529 individuals at risk to a condition that can be detected and treated). The aim of the second
530 level of justification is to judge whether the radiological procedure will usually improve
531 the diagnosis or treatment or will provide necessary information about the exposed
532 individuals.
533
534 "At the third level, the application of the procedure to an individual patient should be
535 justified (i.e., the particular application should be judged to do more good than harm to
536 the individual patient). Hence all individual medical exposures should be justified in
537 advance, taking into account the specific objectives of the exposure and the
538 characteristics of the individual involved."
539
540 The principle of optimization of protection states that "the likelihood of incurring exposures, the
541 number of people exposed, and the magnitude of their individual doses should all be kept as low
542 as reasonably achievable, taking into account economic and societal factors. This means that the
543 level of protection should be the best under the prevailing circumstances, maximizing the margin
544 of benefit over harm" (ICRP 2007a; ICRP 2007c).
545
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546 The principle ofapplication of dose limits states that "the total dose to any individual from
547 regulated sources in planned exposure situations other than medical exposure of patients should
548 not exceed the appropriate limits recommended by the Commission" (ICRP 2007a; ICRP
549 2007c). It is important to note this definition explicitly excludes medical exposure of patients.
550 Dose limits do not apply to medical exposure, which is defined by the ICRP as "the exposure of
551 persons as part of their diagnosis or treatment (or exposure of a patient's embryo/fetus or breast -
552 feeding infant) and their comforters and carers (other than occupational)" (ICRP 2007c). As the
553 ICRP has stated, "Provided that the medical exposures of patients have been properly justified
554 and that the associated doses are commensurate with the medical purpose, it is not appropriate to
555 apply dose limits or dose constraints to the medical exposure of patients, because such limits or
556 constraints would often do more harm than good" (ICRP 2007c). This recommendation against
557 establishing absolute dose limits should not discourage a facility from implementing threshold
558 guidelines for diagnostic procedures that trigger a review of practice at the facility, or from
559 establishing dose notification and alert values for CT (NOTE:citeNEMA standard XR25-2010 to
560 be provided by Ed 2012-08-17).
561
562 When an interventional procedure is indicated, the medical condition being treated and the non-
563 radiation risks of the procedure typically present a substantially greater risk of morbidity and
564 mortality than do the radiation risks (Miller 2008).
565
566 While dose limits do not apply to medical exposures, each physician must always strive to
567 minimize patient irradiation to the dose that is necessary to perform the procedure. Therefore,
568 radiation doses to patients should always be optimized.
569
570 The concept of patient radiation dose optimization is used throughout this document. Dose
571 optimization means delivering a radiation dose to the organs and tissues of clinical interest no
572 greater than that required for adequate imaging and minimizing dose to other structures (e.g., the
573 skin (FDA 1994)). Patient radiation dose is considered to be optimized when imaging is
574 performed with the least amount of radiation required to provide adequate image quality and, for
575 fluoroscopy, adequate imaging guidance (NIH NCI SIR 2005). The goal of every imaging
576 procedure is to provide images adequate for the clinical purpose. What constitutes adequate
577 image quality depends on the modality being used and the clinical question being asked.
578 Imaging requirements depend on the specific patient and the specific procedure. Reducing
579 patient radiation dose to the point where images are inadequate is counterproductive; it results in
580 radiation dose to the patient without answering the clinical question, ultimately resulting in the
581 need for additional radiation dose. Improving image quality beyond what is clinically needed
582 subjects the patient to additional radiation dose without additional clinical benefit. The goal of
583 patient radiation management is to keep patient radiation dose as low as reasonably achievable
584 consistent with the use of appropriate equipment and the imaging requirements for a specific
585 patient and a specific procedure.
586
587 Ideally, dose would be accurately measured or estimated in relevant tissues and organs in real
588 time. As of 2012, this is not possible. Currently, radiation dose is measured differently for CT,
589 fluoroscopically-guided procedures, and radiography due to the endpoint health effect of interest
590 (cancer or acute tissue damage), the way radiation is detected, and the way dose is calculated.
591 The dose metrics and units of measurement used for patient radiation dose measurement are
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DRAFT PROPOSAL
592 necessarily dependent on the equipment and modality being used. Different dose metrics are
593 managed in different ways. For example, during fluoroscopically-guided procedures, it is
594 desirable to optimize kerma area product and reference air kerma (indicators of patient dose)
595 while also minimizing peak skin dose. The most appropriate dose metrics available should be
596 used.
597
598
599 GENERAL STANDARDS FOR PROTECTION AGAINST RADIATION
600
601 Federal facilities must have safety programs in place to protect workers, as required by Public
602 Law 91-596, Section 19 entitled Federal Agency Safety Programs and Responsibilities (Congress
603 2004) and Executive Order 12196 entitled Occupational Safety and Health Programs for Federal
604 Employees (Carter 1980). For medical imaging the standards for protection against ionizing
605 radiation are promulgated by the Nuclear Regulatory Commission (NRC) for radioactive
606 materials in 10CFR20 (USNRC 2012c), and the US Occupational Safety and Health
607 Administration (OSHA) for x-rays in 29CFR1910 (OSHA 2012). If both radioactive materials
608 and x-rays are utilized, then NRC regulations generally take precedence. Portions of the NRC
609 and OSHA regulations, when considered together, establish dose limits for staff and members of
610 the public; requirements for the wearing of dosimeters; requirements for the posting of warning
611 signs; periodic employee training and hazard communication; comprehensive record keeping for
612 exposure monitoring results, periodic facility medical physicist assessments, and preventive
613 interventions; and timely reporting of results of exposure monitoring and exposure incidents to
614 individual employees, including exposures to staffer members of the public that exceed
615 regulatory limits. It is important to note that these dose limits are for occupational, incidental,
616 and public exposure and do not specifically limit the exposure that a patient may receive as a
617 result of medical evaluation or treatment in the process of their personal health care. As of 2012,
618 and consistent with recommendations from ICRP, there is no regulatory limit on the amount of
619 radiation a patient may receive.
620
621 Minors as Workers
622
623 Readers of this document should be aware that the Federal Regulations cited above also provide
624 direction concerning occupational radiation exposure to individuals below the age of 18. Dose
625 limits for these individuals are generally 10% of the occupational dose limits for adults.
626
627 Embryo or Fetus of Pregnant Workers
628
629 As of 2012, the occupationally received dose equivalent to the embryo or fetus of a radiation
630 worker who has voluntarily declared her pregnancy in writing shall not exceed 5 mSv (0.5 rem)
631 during the remainder of the pregnancy, or an additional 0.5 mSv (0.05 rem) if the gestation limit
632 has been or is within 0.5 mSv (0.05 rem) of being exceeded when the declaration is made
633 (USNRC 2012b). This limit does not pertain to the exposure of an embryo or fetus resulting
634 from a medical procedure to the pregnant worker. When a radiation worker informally advises
635 the facility that she is, might be, or is attempting to become pregnant, her past and current
636 exposure values should be evaluated and risks associated with radiation exposure to the fetus
637 should be discussed. If she formally declares her pregnancy (i.e., becomes a "declared pregnant
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DRAFT PROPOSAL
638 woman" per 1OCFR20.1003 (USNRC 2012a)), she should be issued a dosimeter to be worn on
639 the lower abdomen, under the apron, at the level of the fetus, and exchanged monthly, unless
640 such a dosimeter is already being worn. The facility should avoid substantial variation above a
641 uniform monthly exposure rate of 0.5 mSv/month.
642
643 Members of the Public
644
645 The total effective dose equivalent to an individual member of the public should not exceed
646 1 mSv (100 mrem) in a year from occupancy in uncontrolled areas in or near medical radiation
647 facilities (NCRP 2004a). In health care facilities, all non-radiation workers (e.g., janitorial staff,
648 secretaries) should be afforded protection consistent with that afforded members of the public.
649 This is relevant to the design of radiation shielding and occupancy limits.
650
651
652 GENERAL CONCEPTS FOR RADIATION PROTECTION
653
654 There are several principles by which workers can minimize their exposure to x-rays. Most of
655 them are based on certain fundamental concepts concerning x-rays: (1) limiting the time of
656 exposure reduces the dose, (2) except at short distances, radiation intensity is inversely
657 proportional to the square of the distance from the radiation source (Inverse Square Law), and (3)
658 x-rays travel in straight lines from their source and can be attenuated by shielding. Those who
659 are exposed to radiation should judiciously use time, distance, and shielding to limit their
660 radiation dose.
661
662 Humans should be exposed to the unattenuated primary radiation beam(s) of x-ray imaging
663 equipment in federal medical facilities only for medical purposes. For this definition, "medical
664 purposes" include research involving the exposure of human subjects conducted in accordance
665 with the Federal Policy for the Protection of Human Subjects (OSTP et al. 1991). In particular,
666 humans may not be exposed to these unattenuated beams solely for training, to test equipment, or
667 to obtain images for accreditation. The only exception to this requirement is that precision
668 assessments may be made in dual energy x-ray bone densitometry in accordance with the
669 guidelines of the International Society for Clinical Densitometry (ISCD 2007a; ISCD 2007b).
670
671 Optimization of protection is at the heart of a successful radiation control program. It involves
672 evaluating and, where practical to do so, incorporating measures to reduce collective dose and
673 minimize the number of people exposed. In accordance with the ICRP' s principle of
674 optimization of protection, each facility should use, to the extent practicable, procedures and
675 engineered controls to achieve occupational doses and doses to members of the public that are as
676 low as reasonably achievable (ALARA), with economic and social factors being taken into
677 account. The ALARA approach is applied after it has been determined that a proposed activity
678 will not exceed any mandatory dose limit.
679
680 The ALARA approach requires that only people whose presence is necessary are permitted in the
681 room while images are acquired. For radiation protection purposes, it is strongly recommended
682 that these people be shielded from radiation by means such as protective aprons and/or portable
683 shields and maintain as much distance as possible from the point where the x-ray beam intersects
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DRAFT PROPOSAL
684 the patient. To limit worker dose, it is strongly encouraged that the operator be behind a shielded
685 barrier when observing the patient during image acquisition.
686
687
688 RADIATION SAFETY PROGRAM
689
690 A radiation safety program is the mechanism for an institution to ensure that:
691 • the use of ionizing radiation within its purview is performed in accordance with existing
692 laws and regulations,
693 • individual health professionals and technologists are equipped with knowledge of the
694 options available to them as they make benefitrisk determinations and prescribe the
695 appropriate examination for each individual patient, and
696 • x-ray equipment users and the surrounding public receive adequate protection from this
697 radiation.
698 The primary objective is to obtain necessary diagnostic information or interventional results with
699 minimum irradiation of the patient. This also helps keep exposure to staff and members of the
700 public at a minimum. The key personnel and activities involved in managing a radiation safety
701 program are:
702
703 Radiation Safety Officer
704
705 The Radiation Safety Officer (RSO) is responsible for radiation safety. The RSO may be the
706 same person designated for radiation safety for NRC purposes under Title 10, Code of Federal
707 Regulations, Part 35 (USNRC 2012d). An RSO should be designated for each facility that uses
708 ionizing radiation for medical imaging, and should be appointed in writing by the facility
709 director or agency. The RSO shall be permitted to directly communicate with facility executive
710 management. The RSO, whenever possible, should be a qualified expert as defined in this
711 document. The RSO should be a person having knowledge and training in ionizing radiation
712 measurement and evaluation of safety techniques and the ability to advise regarding radiation
713 protection needs (for example, a person certified in diagnostic medical physics by the American
714 Board of Radiology, or in health physics by the American Board of Health Physics, or those
715 having equivalent qualifications). The RSO has the following specific responsibilities:
716
717 1. Establish and implement radiation safety procedures and review them periodically to assure
718 their conformity with regulations and good radiation safety and medical physics practices.
719 2. Instruct personnel in regulatory requirements and proper radiation protection practices
720 before they begin working with radiation and periodically thereafter to maintain and update
721 that knowledge.
722 3. Conduct or supervise radiation surveys where indicated and keep records of such surveys
723 and tests, including summaries of corrective measures recommended and/or instituted.
724 4. Assure that area monitoring and personnel monitoring devices are used as required and
725 records are kept of the results of such monitoring. This function requires reviewing the
726 monitoring reports promptly to ensure that public and personnel doses do not exceed
727 regulatory limits and are ALARA, making dosimetry records available to each worker at
728 any time, and periodically informing workers of their dose record. These records will be
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DRAFT PROPOSAL
729 kept in a suitable organized file (readily retrievable but not necessarily on site) for the life
730 of the facility or as legally required.
731 5. Assure that any warning signals on imaging equipment and suites are regularly checked for
732 proper function and that required signs are properly posted.
733 6. Monitor compliance with the requirements of regulations and the requirements specified in
734 the facility's standard operating procedures.
735 7. In conjunction with a qualified physicist, promptly investigate each known or suspected
736 case of excessive or abnormal exposure, determine the causes, take steps to prevent its
737 recurrence, monitor such corrective actions, and make appropriate reports.
73 8 8. Ensure that required notifications and reports in the case of personnel overexposures and
739 radiation medical events are submitted as required by regulations.
740 9. Promptly notify facility executive management of significant safety hazards, significant
741 violations of regulations, exposures of staff or members of the public that exceed regulatory
742 requirements, and radiation medical events.
743 10. Review or have a qualified expert review, prior to construction or modification, plans for
744 rooms in which x-ray producing equipment is to be installed, including room layout,
745 shielding (AAPM 2006c; NCRP 2004a), and viewing and communications systems, and
746 verify that the shielding is installed according to plan and functions as designed before
747 clinical use of the equipment.
748
749 Qualified Physicist
750
751 The services of a qualified physicist are essential for the optimal use of medical imaging. The
752 following services should be performed by or under the supervision of a qualified physicist:
753
754 1. Participate in evaluation and selection of equipment
755 2. Conduct acceptance testing of new equipment
756 3. Monitor imaging systems at least annually
757 4. Evaluate, in conjunction with the RSO, unexpected radiation events
758 5. Oversee the technical Q A program
759 6. Investigate the root causes of image quality issues and identify appropriate solutions.
760 7. Design or review and approve x-ray room radiation shielding
761 8. Perform verification surveys of x-ray room shielding
762 9. Periodically review existing imaging protocols
763 10. Assist with development and evaluation of new and revised imaging protocols
764 11. Perform patient-specific radiation dose calculations (e.g., fetal dose calculations)
765 12. Provide training on quality control and radiation safety
766 13. Ensure that instruments used to monitor x-ray imaging systems are appropriate for the task,
767 appropriately calibrated for the task (e.g., energy and dose rate measurements), and
768 maintained
769 14. Evaluate the radiation-related aspects of research protocols
770
771 Personnel and Area Monitoring
772
773 Each worker who is expected to receive more than 10% of the applicable dose limit should be
774 required to wear one or more dosimeters. There shall be a procedure for regular issuance and
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DRAFT PROPOSAL
775 replacement of dosimeters for exposure evaluation, and records of the doses received shall be
776 retained as required by NRC in 10CFR20 (USNRC 2012c) and OSHA in 29CFR1910.1096
777 (OSHA 2012). When a protective apron is worn, one dosimeter should be worn at the collar
778 outside the apron. A second dosimeter may be worn on the abdomen under the apron. The two
779 dosimeter method provides a more accurate method of assessing effective dose (NCRP 1995).
780 When multiple dosimeters are issued to an employee, each dosimeter should be labeled to
781 indicate the location on the body where it is to be worn. Facilities should ensure that workers
782 wear dosimeters as required, and in the designated locations; failure to do so can result in
783 incorrect dose assessments. Periodic assessments and feedback to employees regarding their
784 exposures are particularly important. If there is a question, the facility can also post dosimeters
785 in public areas adjacent to rooms where x-rays are produced in order to quantify the amount of
786 radiation a person in those areas might receive. Facilities/agencies should use methods for
787 estimating individual doses based on the goal of assigning accurate doses. Federal regulatory
788 agencies should adopt methods and procedures consistent with NCRP Report No. 122, which
789 provides recommended methods for determining effective dose (E) (NCRP 1995).
790
791 Patient Safety
792
793 As with all medical procedures, there are critical elements of patient safety that must be
794 observed. The first critical element is ensuring that the correct patient undergoes the specified
795 diagnostic test or interventional procedure, and that the examination is performed on the
796 appropriate body part. To that end, each facility should have in place a specified method for
797 verification of patient identity prior to events such as administration of medication or surgical
798 procedures. These precautions should also be extended to diagnostic and interventional imaging.
799 If the medical procedure involves intervention or a specific side of the patient's anatomy, the
800 specific body part should be confirmed prior to the procedure. The precautions should be
801 commensurate with the risk from the examination or procedure, with greater precautions being
802 taken for procedures of greater risk.
803
804 Radiation Safety Procedures for Fluoroscopy
805
806 It is strongly recommended that, other than for the patient being examined, only staff and
807 ancillary personnel required for the procedure, or those in training, be in the room during the
808 fluoroscopic examination (AAPM 1998; ACR 2008c). No body part of any staffer ancillary
809 personnel involved in a fluoroscopic examination should be in the primary beam. However, if
810 primary beam exposure is unavoidable, it should be minimized. It is essential that all personnel
811 in the room during fluoroscopic procedures be protected from scatter radiation by either whole-
812 body shields or protective aprons. For procedures performed using microampere fluoroscopy
813 systems, a qualified physicist should determine if aprons are required.
814
815 Aprons should provide the desired protection at an acceptable weight, because the apron weight
816 itself can pose a substantial ergonomic risk to its wearer. Apron weight can be reduced by using
817 thinner lead or by replacing lead, completely or partially, with a combination of one or more
818 other materials that have the same or better attenuation for the scattered radiation from
819 fluoroscopic beams. Though 0.5 mm lead-equivalent aprons are considered the standard as of
10
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DRAFT PROPOSAL
820 2012, an apron with thinner lead equivalence may provide adequate protection. Based on the
821 calculation of effective dose (E} from dual monitors, a 0.3 mm lead-equivalent apron will result
822 in a value of E that is only moderately higher (7 to 16 %) than a 0.5 mm lead-equivalent apron
823 (NCRP 1995). The two-dosimeter method described above under PERSONNEL AND AREA
824 MONITORING may be preferable for monitoring personnel in the room during high dose
825 interventional procedures. Monthly dose monitoring can also be implemented to ensure that staff
826 members who use garments with < 0.5 mm lead equivalent thickness continue to maintain an
827 occupational dose below the required dose limits. With these precautions in place, it is quite
828 possible to provide adequate protection with a 0.3 5 mm or less lead equivalent thickness.
829
830 Thyroid and eyes should be protected if the potential exposure to the worker will exceed 25% of
831 the annual regulatory dose limits for those organs. It is strongly recommended that lead
832 personnel protective equipment (e.g., aprons, gloves, thyroid collars) be evaluated at least
833 annually for lead protection integrity using visual and manual inspection (Miller et al. 2010b;
834 NCRP 2010). If a defect in the attenuating material is suspected, radiographic or fluoroscopic
835 inspection may be performed as an alternative to immediately removing the item from service.
836 Protective aprons, gloves and thyroid shields should be hung or laid flat and never folded, and
837 manufacturer's instructions should be followed. Consideration should be given to minimizing
838 the radiation exposure of inspectors by minimizing unnecessary fluoroscopy.
839
840 Special Patient Populations
841
842 Specific special populations addressed here include:
843
844 1. Pregnant patients
845 2. Pediatric patients
846 3. Patients enrolled in a research protocol
847
848 Occupational radiation exposure to minors and to the fetus of a pregnant worker is discussed in
849 the section General Standards for Protection Against Radiation.
850
851 Pregnant patients
852
853 Because of the special risk that radiation exposure poses to the embryo or fetus, each facility
854 should establish and implement procedures to determine, before conducting an examination or
855 procedure, whether a female patient of childbearing age may be pregnant.
856
857 Signs should be posted in suitable locations, such as patient reception areas and procedure
858 rooms, asking female patients to notify staff if they might be pregnant. Consideration should be
859 given to alternate tests or procedures, such as ultrasound, that would not expose the embryo or
860 fetus to ionizing radiation, or to modifying the examination or procedure to reduce the radiation
861 dose to the embryo or fetus.
862
863 Evaluation of the benefit:risk ratio in relation to the radiation dose from medical imaging in a
864 pregnant woman is very complex. In instances where a study using ionizing radiation is deemed
865 necessary, every effort should be made to avoid exposing the fetus to the direct radiation beam.
11
-------
DRAFT PROPOSAL
866 If a patient is pregnant, a radiologist, radiation oncologist, or other physician knowledgeable in
867 the risk from the radiation exposure should work with the patient in making the decision whether
868 to perform the examination or procedure. There should be a discussion of the benefits and risks
869 with a pregnant patient prior to the imaging unless an emergent need for the imaging or her
870 condition precludes this. If a previously unrecognized pregnancy is identified after a procedure,
871 the referring physician should be notified and the patient counseled as appropriate.
872
873 The precautions should be commensurate with the risk from the examination or procedure to be
874 performed, with greater precautions being taken for procedures imparting larger radiation doses
875 to the abdomen or pelvic region of the patient. The physician might consider delaying the
876 procedure until after pregnancy so as to avoid exposing the embryo or fetus. For procedures that
877 may impart a dose to this region, and especially for those exceeding 0.05 Gy (5 rad), the
878 anticipated dose and associated risks should be included as part of informed consent and a serum
879 pregnancy test should be obtained, unless a physician determines that the delay caused by
880 performing the test would harm the patient. A confirmatory pregnancy test would not be
881 necessary if pregnancy can be excluded by documented surgical or medical history. Procedures
882 that may impart a dose to the embryo or fetus exceeding 0.05 Gy (5 rad) are prolonged
883 fluoroscopic procedures to the abdomen or pelvis and CT imaging involving two or more scans
884 of the abdomen or pelvis.
885
886 The dose to a fetus should be estimated. If the dose to the embryo or fetus could exceed 0.05 Gy
887 (5 rad), a formal dose assessment should be performed by a qualified physicist and provided with
888 consultation to the referring physician so that the patient can be advised accordingly. Doses at or
889 above 0.1 Gy (10 rad) warrant discussions between the patient and her physician of potentially
890 adverse fetal effects, and the fetal dose assessment should be included in the medical record.
891
892 Pediatric patients
893
894 Children are more sensitive to radiation and also have greater expected remaining life spans than
895 adults. As such, children represent a population at greater risk for subsequent development of
896 radiation induced cancer than adults. This difference in the benefitrisk ratio should be
897 considered in the prescription of medical imaging requiring ionizing radiation. Alternative
898 imaging modalities that do not use ionizing radiation, such as ultrasound or MRI, should be
899 considered for imaging children.
900
901 Protocols for all ionizing radiation imaging should be "child-sized" or optimized so that the dose
902 is appropriate for the size of the infant or child (FDA 2001; Strauss et al. 2010). For
903 radiography, fluoroscopy, and CT, this key principle holds true. For example, unlike abdominal
904 CT studies performed in adults, pediatric CT studies usually do not require multiple passes
905 through the child's body. This reduces the radiation dose to the child without compromising
906 diagnosis.
907
908 Patients enrolled in a research protocol
909
910 All research involving human subjects that is conducted, supported, or otherwise subject to
911 regulation by any Federal department or agency must conform to the most current version of the
12
-------
DRAFT PROPOSAL
912 Federal Policy for the Protection of Human Subjects (FPPHS) (OSTP et al. 1991). This policy
913 requires approval of research protocols by a properly constituted institutional review board (IRB)
914 and obtaining informed consent from the patient.
915
916 Many protocols use radiation that is medically indicated (also referred to as "standard-of-care ").
917 Medically-indicated radiation is used to diagnose or guide treatment as a non-research medical
918 procedure for clinical management of the research subject. The radiation dose from a medically-
919 indicated procedure done as part of a research study should not require additional justification,
920 review, and approval by an IRB. When the radiation exposure is described as indicated for
921 research (the radiation use does not meet the criteria of "medically indicated") it must be
922 reviewed and approved. IRBs have responsibility for oversight of research involving human
923 subjects, but usually seek the advice of the institution's Radiation Safety Committee regarding
924 the radiation risk from any non-medically indicated radiation use that is a component of the
925 research.
926
927 Analysis of Risk from Radiation
928
929 An analysis of risk to the human research subjects, including that from radiation exposure, must
930 be performed prior to preparation of the information to be provided to the subjects to seek
931 informed consent and prior to review of the research study by the IRB. The risks of both
932 deterministic and stochastic effects from the radiation exposure should be considered. For
933 consideration of the risk of deterministic effects, the maximal doses to individual organs and
934 tissues should be estimated, although dose rate and dose fractionation may also be considered.
935
936 The risk from stochastic effects, particularly cancer, should also be considered. Ideally, this risk
937 should be calculated from estimating doses to individual organs and tissues and using organ and
938 tissue specific risk coefficients that account for the age and gender of the subject. The
939 International Commission on Radiation Units and Measurements (ICRU) provides useful
940 information for determining patient dose (ICRU 2005, or most current version). However, for
941 many imaging procedures, this approach would consume considerable resources and requiring it
942 would discourage many research studies from being performed.
943
944 The ICRP developed the quantity effective dose (E) for radiation protection purposes to assess
945 the risk of detriment to workers from stochastic effects caused by occupational exposure to
946 ionizing radiation (Harrison and Streffer 2007; ICRP 1991a). This quantity was intended to be
947 applied to a population of working-age adults of both genders. Although effective dose was not
948 intended to be used for assessing risk from medical exposures, it is commonly used to convey the
949 potential risk from radiation exposure for subjects participating in investigational protocols
950 (Martin 2007). For many imaging procedures, the effective dose can be estimated easily.
951 Furthermore, effective dose provides a single quantity from participating in a research study that
952 can be compared to other sources of radiation exposure (e.g., medical procedures and natural
953 background radiation). From the research subject's perspective, this comparison is simple and
954 expresses the risk in a meaningful way. The effective dose may be used for estimating risk from
955 stochastic effects to human research subjects, but should not be used without considering its
956 appropriateness in light of the characteristics of the study population, including their ages and
957 genders, the body parts being irradiated, and their expected life-spans. ICRP Publication 62
13
-------
DRAFT PROPOSAL
958 (ICRP 1991b) provides guidance on the use of effective dose in estimating risk to human
959 subjects.
960
961 Informed Consent for Research Involving Radiation
962
963 To enroll in any research study using human subjects, participants must be knowledgeable about
964 the risks, benefits, privacy considerations and other matters. They must participate voluntarily
965 and must provide written informed consent using an IRB-approved consent form. Requirements
966 for human research in x-ray imaging facilities are addressed in the Federal Register (OSTP et al.
967 1991) and are specified in the current Code of Federal Regulations sections that apply to
968 individual facility operations (e.g., 32CFR219 for DoD, 45CFR46 for DHHS, 40CFR26 for
969 EPA, and 38CFR16 for VA). Appendix A contains sample informed consent templates for the
970 research use of radiation, adapted from those used by NIH in 2012 (Nffl 2008a; NIH 2008b;
971 NIH 2010).
972
973 These consent documents have been developed for use when patients are irradiated for research
974 purposes as opposed to being irradiated for clinical care. These documents explain risk based on
975 effective dose. The maximum level of radiation risk should be expected to be minimal, minor to
976 intermediate, or moderate when the respective societal benefit is minor, intermediate to
977 moderate, or substantial (ICRP 1991b). The specific values of numerical dose for each of these
978 ranges may vary according to the specific IRB and the specific research population. The sample
979 consent templates in Appendix A may be considered as a starting point for IRB consideration for
980 the general adult population. These consent templates should be modified as appropriate to meet
981 the particular requirements or needs of a given study.
982
983 Occupational Radiation Safety Training
984
985 Each facility should train staff who operate x-ray producing equipment or who are routinely
986 exposed to radiation by the equipment. Training should be provided initially prior to utilization
987 of the equipment and at least annually thereafter. The training should be commensurate with risk
988 to the staff and to the patient. It should include the risks from exposure to ionizing radiation,
989 regulatory requirements, recommendations of this guidance document, facility requirements,
990 proper operation of the equipment, methods for maintaining doses to staff within regulatory
991 limits and as low as reasonably achievable, and guidance for protecting the patient and embryo
992 or fetus.
993
994 Notification and Reporting Requirements
995
996 If radiation exposures to staff or members of the public exceed regulatory limits, the facility shall
997 make notifications and reports as required by the NRC or OSHA (OSHA 2012; USNRC 2012c).
998
999
14
-------
DRAFT PROPOSAL
1000 STRUCTURAL SHIELDING AND DOOR INTERLOCK SWITCHES
1001
1002 To prevent inadvertent patient injury or the need to repeat exposures of patients, it is strongly
1003 recommended that interlock switches that terminate x-ray production not be placed on doors to
1004 any diagnostic or interventional x-ray room (NCRP 2004a).
1005
1006 For the structural shielding of rooms containing x-ray imaging or x-ray-producing devices, the
1007 shielding design goal should be 5 mGy in a year to any person in controlled areas. For
1008 uncontrolled areas, the shielding design goal should be a maximum of 1 mGy to any person in a
1009 year (0.02 mGy per week) (NCRP 2004a). Shielding design for and acceptance testing surveys
1010 of imaging rooms should be performed or reviewed by a qualified physicist using appropriate
1011 methodology such as is provided in NCRP reports. Whenever room modifications are performed
1012 or the assumed shielding parameters change (e.g., new equipment, increased workload, or altered
1013 use of adjacent spaces), the suitability of the design should be reviewed by a qualified physicist.
1014 The shielding design calculations, as-built shielding plans, and the report on the acceptance
1015 testing of the structural shielding should be kept for the duration of use of the room for x-ray
1016 imaging. The American Association of Physicists in Medicine guidance should be used as
1017 appropriate, for modalities not covered in NCRP reports. At the time of this writing, this
1018 includes guidance for PET/CT shielding (AAPM 2006c).
1019
1020 Mobile radiographic equipment is frequently used for bedside examinations. Effective radiation
1021 protection in these circumstances is normally provided through exposure time and distance
1022 (NCRP 1989b; NCRP 2000; NCRP 2004a). When mobile radiographic or fluoroscopic
1023 equipment is used in a fixed location, or frequently in the same location, it is strongly
1024 recommended that a qualified expert evaluate the need for structural shielding (NCRP 2004a).
1025 When radiographic or fluoroscopic equipment is used in a temporary facility (e.g., field
1026 hospital), the effective use of distance, exposure time, or non-structural shielding may eliminate
1027 the need for structural shielding.
1028
1029
1030 REQUESTING AND PERFORMING STUDIES INVOLVING X-RAYS
1031
1032 The following section uses the terms Referring Medical Practitioner and Radiological Medical
1033 Practitioner. The Referring Medical Practitioner is a health professional who, in accordance with
1034 state and federal requirements, may refer individuals to a Radiological Medical Practitioner for
1035 medical exposure (IAEA 201 Ib). The Radiological Medical Practitioner is a health professional,
1036 with education and specialist training in the medical uses of radiation, who is competent to
1037 independently perform or oversee procedures involving medical radiation exposure in a given
1038 specialty (IAEA 201 Ib).
1039
1040 REQUESTING STUDIES: REFERRING MEDICAL PRACTITIONERS (REQUESTING
1041 HEALTH PROFESSIONALS)
1042
1043 A medical procedure should only be performed on a patient if it is appropriately justified and
1044 optimized for that particular patient. In this context, "appropriateness" is generally defined in
1045 terms of benefit and risk. The RAND corporation has developed a definition of "appropriate"
15
-------
DRAFT PROPOSAL
1046 that is widely used: the expected health benefit (i.e., increased life expectancy, relief of pain,
1047 reduction in anxiety, improved functional capacity) exceeds the expected negative consequences
1048 (i.e., mortality, morbidity, anxiety of anticipating the procedure, pain produced by the procedure,
1049 misleading or false diagnoses, time lost from work) by a sufficiently wide margin that the
1050 procedure is worth doing (NHS 1993; Sistrom 2008). In other words, the anticipated clinical
1051 benefits should exceed all anticipated procedural risks, including radiation risk. This implies that
1052 radiation should be included in the benefitrisk evaluation for each patient both before and during
1053 any procedure.
1054
1055 As with any medical procedure, the requesting or "ordering" provider (i.e., the Referring
1056 Medical Practitioner) should have adequate knowledge of the patient, understand the nature of
1057 the proposed and alternative imaging procedures, and fully comprehend the medical diagnostic
1058 and treatment options available in order to be able to assess the benefitrisk ratios for the imaging
1059 procedures. These ratios balance the benefit of the diagnostic examination being requested
1060 against the stochastic and deterministic risks to the patient from radiation exposure during
1061 imaging, as well as the benefits and risks from alternative radiological and non-radiological
1062 procedures. The Referring Medical Practitioner (with privileges at the facility/within the
1063 healthcare network for the ordering of radiograph!c studies) should have determined that
1064 sufficient clinical history, symptoms, signs, or findings exist to necessitate the examination. All
1065 exposures to radiation should involve a benefitrisk analysis, in order to ensure that the expected
1066 benefits of the examination outweigh the potential risks, and that the most appropriate
1067 radiological or non-radiological procedure is selected on the basis of its benefit:risk ratio. In all
1068 cases, the use of radiation in diagnostic medical imaging should be justified and optimized. This
1069 is the responsibility of all involved providers and technologists. Dose management begins when
1070 a patient is considered for a procedure involving ionizing radiation, involves equipment setup
1071 before the exam begins, and ends when any necessary radiation-related follow-up is completed.
1072
1073 Physicians and licensed independent practitioners (Referring Medical Practitioners) who have
1074 the legal authority and privileges to request diagnostic imaging studies involving ionizing
1075 radiation should have a basic understanding of radiation effects and protection methods. Also,
1076 they should have an appreciation for the radiation dose involved in a study and the potential
1077 effects of this dose over the lifetime of the patient to properly assess the benefit:risk ratio. The
1078 justification of medical exposure for an individual patient should be carried out by the Referring
1079 Medical Practitioner, in consultation with the Radiological Medical Practitioner when
1080 appropriate. Each health care facility should establish a formal mechanism whereby Referring
1081 Medical Practitioners have sources of information available at the time of ordering regarding
1082 appropriate diagnostic imaging methods to answer the clinical question and to optimize ionizing
1083 radiation dose to the patient. These may include decision support software or appropriateness
1084 criteria. A mechanism for consultation with Radiological Medical Practitioners should also be
1085 made available.
1086
1087 One of the most important methods for reducing radiation exposure is the elimination of
1088 clinically unproductive examinations. This continues to be a significant, but largely unrealized
1089 opportunity. Appropriate education of the requesting physician, utilization of existing current
1090 recommendations (such as the ACR Appropriateness Criteria (ACR 2012)) and consultation with
1091 a Radiological Medical Practitioner prior to generation of the examination request can all
16
-------
DRAFT PROPOSAL
1092 improve the probability that the most appropriate examination is performed relative to the
1093 clinical question. Automated algorithms integral to electronic ordering systems have the
1094 capability to alert the referring provider to more appropriate examinations, and can alert them to
1095 unnecessary repeat examinations.
1096
1097 Follow-up examinations are commonly done so that significant changes in clinical information
1098 are obtained for making proper decisions on continuation or alteration of the management of the
1099 patient. These examinations may result in unnecessary patient exposure if repeated before
1100 significant changes in patient status occur; therefore, it is recommended that they be done only at
1101 time intervals long enough to make proper decisions concerning continuation or alteration of
1102 treatment.
1103
1104 Qualifications to Request X-ray Examinations
1105
1106 Requests for imaging examinations involving the use of x-rays in Federal health care facilities
1107 should be made only by physicians or other Referring Medical Practitioners who are licensed in
1108 the United States or one of its territories or possessions and privileged within the healthcare
1109 facility or network. Properly trained individuals such as physician assistants and persons in
1110 postgraduate medical training status do not have to meet the above requirements, but should be
1111 under the general supervision of a licensed physician who does.
1112
1113 It is recognized that medical students, interns, residents, and some physician assistants may not
1114 have developed medical judgment as to which test would be most efficacious. Such lack of
1115 experience is remedied by work under conditions where there is sufficient expert supervision and
1116 radiology providers available for consultation who can monitor the appropriateness of
1117 examinations based on the clinical history and can provide assistance.
1118
1119 In addition to the privileges for which broad qualifications are needed, there are a number of
1120 specialties which require only limited types of x-ray examinations. For example, Doctors of
1121 Dental Surgery or Dental Medicine may request appropriate examinations of the head, neck, and
1122 chest, although such requests are normally confined to the oral region.
1123
1124 Variances to the above qualification requirements should occur only for emergency or life-
1125 threatening situations, such as natural disasters. Also, non-peacetime operations in the field or
1126 aboard ship could require such variances. Equipment designed for field use might need to be
1127 operated by those personnel available to assist in the performance of necessary medical, dental,
1128 and veterinary services.
1129
1130 PERFORMING AND SUPERVISING STUDIES: RADIOLOGICAL MEDICAL
1131 PRACTITIONERS AND TECHNOLOGISTS
1132
1133 Responsible use of medical, dental, and veterinary x-ray equipment involves restricting its
1134 operation to properly qualified and supervised individuals. Such a policy should be established
1135 for each x-ray facility by the responsible authority upon the recommendations of medical, dental,
1136 and veterinary staff. Eligible radiological medical practitioners include those who are granted
1137 privileges for equipment use on the basis of the needs of patients served by the facility. These
17
-------
DRAFT PROPOSAL
1138 are privileges to use radiation-emitting equipment and are separate from privileges to perform
1139 procedures. Such privileges might include, as part of their practice, the use of CT equipment by
1140 radiologists and cardiologists; the use of fluoroscopes by cardiologists, radiologists, urologists,
1141 and others; and the use of dental x-ray equipment by dentists. Before radiological medical
1142 practitioners are granted equipment use privileges, it is strongly recommended that they receive
1143 adequate training in equipment use and radiation protection. However, specific protocols
1144 limiting equipment use privileges to specified types of radiological medical practitioners should
1145 be part of the written policy statement.
1146
1147 After completion of an accredited educational program and certification by a state or voluntary
1148 credentialing organization, radiologic technologists should be able to produce radiographic
1149 images with lower average patient doses than incompletely-trained or non-credentialed
1150 operators. Non-credential ed operators may have little or no formal training in anatomy, patient
1151 positioning, or radiation protection practices. Inadequately trained operators are likely to
1152 irradiate patients and themselves unnecessarily (EPA 2000). Personnel responsible for image
1153 acquisition should be trained in patient preparation and positioning, selection of technique
1154 factors and acquisition parameters, radiation protection measures, routine equipment QC, digital
1155 image post-processing and image processing. They should also be able to reduce to a minimum
1156 the number of repeat examinations. Performance of imaging examinations by incompletely
1157 trained personnel is not justified except for emergent circumstances.
1158
1159 In order to achieve lower patient doses, the operator's manual should be readily available to the
1160 user, and equipment operation should be guided by the manufacturer's instructions, including
1161 any appropriate adjustments for optimizing dose and ensuring adequate image quality.
1162
1163 Radiological Medical Practitioners
1164
1165 A Radiological Medical Practitioner is a health professional, with education and specialist
1166 training in the medical uses of radiation, who is competent to independently perform or oversee
1167 procedures involving medical exposure in a given specialty. Within the Radiology department,
1168 this individual is typically a radiologist. Other individuals who use ionizing radiation for
1169 imaging, usually outside the Radiology department (e.g., cardiac catheterization or fluoroscopy
1170 in the operating room), are also considered Radiological Medical Practitioners. These
1171 individuals, when acting as a Radiological Medical Practitioner, have the same responsibilities
1172 for imaging protocols and for supervising equipment operation that would otherwise be assigned
1173 to a radiologist. The Radiological Medical Practitioner is also responsible for optimizing the
1174 dose of ionizing radiation.
1175
1176 Radiologists
1177
1178 A radiologist is a licensed physician or osteopath who is certified in Radiology or Diagnostic
1179 Radiology by the American Board of Radiology or the American Osteopathic Board of
1180 Radiology (AOBR), or has completed a diagnostic radiology residency program approved by the
1181 Accreditation Council for Graduate Medical Education (ACGME) or the American Osteopathic
1182 Association (AOA). Within the Radiology department, the radiologist generally serves as the
18
-------
DRAFT PROPOSAL
1183 Radiological Medical Practitioner. In addition to interpreting imaging studies, radiologists set
1184 protocols for examinations involving x-ray systems and play a critical role in the performance of
1185 studies. Imaging protocols should be devised for each imaging system and each imaging study.
1186 These protocols should provide adequate image and study quality while optimizing the radiation
1187 dose, particularly to radiosensitive tissues. Considerations include identifying the appropriate
1188 area of coverage, collimation, number of views to be acquired, and image quality needs (which
1189 dictates the required x-ray beam energy and intensity). For CT, this includes CT-specific
1190 technique factors, area of coverage, and the number of CT examination phases. Radiologists are
1191 a source of knowledge on the advantages and disadvantages of different imaging modalities and
1192 should be consulted when that expertise is needed.
1193
1194 Medical Radiologic Technologists
1195
1196 Medical Radiologic Technologists (MRTs) and Registered Cardiovascular Invasive Specialists
1197 (RCIS) having appropriate radiation and other training are the personnel who operate the
1198 imaging equipment, deliver the radiation to the patients and capture the diagnostic images. As
1199 such, they are extremely important in the optimized use of diagnostic imaging. Operator
1200 competence is normally achieved by successful completion of a training program which provides
1201 both a didactic base and sufficient practical experience. The training program should be
1202 accredited by a mechanism acceptable to the appropriate credentialing organization, e.g., the
1203 American Registry of Radiologic Technologists or Cardiovascular Credentialing International
1204 (CCI). Continuing competence and professional growth should be encouraged with specific
1205 opportunities to further the technologist's knowledge and skills through attendance at workshops
1206 or by other means of training.
1207
1208 The radiologic technologist should be familiar with and facile at utilizing the imaging systems
1209 and the techniques and technology available to them to reduce patient radiation dose while
1210 producing clinically adequate images. As a critical part of the healthcare team, they should be
1211 empowered to question techniques and requests when alternatives which would deliver lower
1212 doses are available.
1213
1214 SCREENING AND ADMINISTRATIVE PROGRAMS
1215
1216 Screening programs using ionizing radiation should be justified, and the doses should be
1217 optimized for screening. It is important to keep requirements current with technological
1218 advances. There are several reasons why individuals without known disease or symptoms may
1219 be referred for imaging examinations. Some are specifically for administrative or occupational
1220 safety programs such as the annual postero-anterior chest radiograph acquired to evaluate for
1221 pneumoconiosis in coal, silica and asbestos workers. Self-referral by patients for screening
1222 imaging to evaluate for disease in the absence of symptoms is an increasingly common
1223 occurrence whose appropriateness should be weighed and the individual counseled on the
1224 benefits and risks. If screening has been shown to have a positive benefitrisk ratio, it is
1225 generally warranted. As an example, in 2012, one accepted screening program is mammography
1226 (ACR 2009b). Generally, neither screening nor elective x-ray examinations should be performed
1227 on pregnant women.
1228
19
-------
DRAFT PROPOSAL
1229 Chest Radiography
1230
1231 Screening for tuberculosis is no longer performed in the United States with chest radiography,
1232 although this technique may still be required during disaster relief and humanitarian operations
123 3 in other parts of the world.
1234
1235 "Routine" radiographs without specific indications or symptoms should not be performed on
1236 admission to the hospital or while an inpatient.
1237
1238 Standard postero-anterior chest radiographs are performed periodically to evaluate certain
1239 populations with high occupational risk for lung disease. These populations include coal miners,
1240 asbestos workers, silica workers and a few other specific populations. There are typically
1241 specific requirements for these images; yet, as with all other images, it is important to optimize
1242 the radiation dose delivered to the individual.
1243
1244 Mammography
1245
1246 Breast cancer is a common and significant health risk in the United States. Because of the
1247 importance of early detection in control and survival, mammography is an important screening
1248 modality. This technique has improved considerably since the publication of Federal Guidance
1249 Report 9 (EPA 1976), especially with respect to reducing radiation dose per examination.
1250 Women and their health care providers are encouraged to refer to the most current NCI
1251 recommendations when deciding upon breast cancer screening examinations. Mammography
1252 facilities must comply with the Mammography Quality Standards Act (MQSA) regulations
1253 (FDA2012c).
1254
1255 REFERRAL AND SELF-REFERRAL EXAMINATIONS
1256
1257 There are two types of self-referral. One is patient self-referral, where patients refer themselves
1258 for an imaging procedure without having a physician request (referral). The other is physician
1259 self-referral where physicians see patients, decide to perform imaging procedures on those
1260 patients, and then refer the patients to themselves or their own medical practice for the
1261 procedure.
1262
1263 Patients Requesting Imaging on Themselves without a Referral from a Licensed
1264 Independent Practitioner (Referring Medical Practitioner)
1265
1266 With the increased capabilities of imaging systems and particularly with CT imaging, there has
1267 been an increased interest in and demand for use of this technology to screen for pre-clinical
1268 disease in the general population. Such screening programs should be subjected to rigorous
1269 scientific evaluation, as has been done for mammography, to ensure that the risk posed to the
1270 population screened does not outweigh the benefits in detection of disease.
1271
1272 Physician Self-Referral
1273
1274 In this context, self-referral examinations are examinations requested or ordered by the same
20
-------
DRAFT PROPOSAL
1275 physician who subsequently performs or interprets them. They are frequently performed by
1276 equipment operators lacking adequate training and having supervision by health professionals
1277 with inadequate radiologic experience. Some examinations performed by non-radiologists may
1278 occur because of the convenience of having the x-ray unit and the patient in the same location,
1279 or, in the case of civilian contract services, need to justify the equipment purchased or
1280 maintenance costs.
1281
1282 Unnecessary radiation exposure caused by self-referral practices that are not diagnostically
1283 relevant generally need not occur in Federal health care institutions where facilities staffed by
1284 radiologists are normally provided. Exceptions could be small operational units, such as ships,
1285 field units, or isolated stations where the normal workload does not justify a staff radiologist.
1286 Thus, the conduct of self-referral x-ray examinations should be permitted only by a physician
1287 whose qualifications to supervise, perform, and interpret diagnostic radiologic procedures have
1288 been demonstrated to the appropriate authorities.
1289
1290 It is recognized that limited self-referral type examinations are performed in Federal medical
1291 centers in certain clinical specialties. The use of such self-referral x-ray examinations should,
1292 however, be limited to studies unique to and required by the specialty of the physician
1293 performing them and be consistent with a peer review policy.
1294
1295 Self-referral practices in federal facilities are expected to be immune to economic considerations
1296 for the referring physician. Self-referral practices in contract civilian facilities can lead to
1297 overutilization due to economic incentives for the referring physician and should be prohibited.
1298 Exception may be made in remote areas where no practicable alternative exists.
1299
1300 COMMUNICATION AMONG PRACTITIONERS
1301
1302 Optimal medical care requires appropriate interaction between the Referring Medical Practitioner
1303 and the Radiological Medical Practitioner. The information technology system also plays an
1304 important role. Requests for x-ray examinations should be considered as medical consultations
1305 between the Referring Medical Practitioner and the Radiological Medical Practitioner. A request
1306 should state the diagnostic objective of the examination and should detail relevant medical
1307 history including results of previous diagnostic x-ray examinations and other relevant tests.
1308
1309 Whenever possible the Radiological Medical Practitioner should review all examination requests
1310 requiring fluoroscopy, CT, or other complex or high-dose studies before the examination is given
1311 and preferably before it is scheduled. For this reason, it is important that a thorough and accurate
1312 patient history be included with each examination request. Based upon the clinical question,
1313 history, and relevant available previous studies, the Radiological Medical Practitioner should
1314 direct the examination using standard protocols, with any appropriate addition, substitution, or
1315 deletion of views or sequences. It is preferable that changes in the examination be done in
1316 consultation with the Referring Medical Practitioner.
1317
1318 Effective communication of the findings is an essential component of imaging studies. Facilities
1319 are strongly encouraged to have policies on the communication of findings that are consistent
1320 with the guidelines of accrediting organizations and professional societies (ACR 2010).
21
-------
DRAFT PROPOSAL
1321
1322 The provision of care by more than one medical facility may result in duplication of imaging
1323 studies. To prevent this, and as technology permits, the Referring Medical Practitioner should
1324 review the patient's medical record to determine whether the proposed imaging study would
1325 duplicate a previous study. This requires that the reports and images from all studies are
1326 accessible through the patient's Electronic Health Record (EHR) (Congress 2007).
1327
1328 When referral from one facility to a second is anticipated, only the studies needed for proper
1329 referral should be performed in the first facility. Those imaging studies should be made
1330 available to the second medical facility concurrent with the transfer, either electronically or in
1331 hard copy format.
1332
22
-------
DRAFT PROPOSAL
1333 TECHNICAL QUALITY ASSURANCE IN MEDICAL IMAGING WITH X-RAYS
1334
1335 Quality assurance refers to those steps that are taken to make sure that a facility consistently
1336 produces images that are adequate for the purpose with optimal patient exposure and minimal
1337 operator exposure. Quality assurance may be divided into two major categories: quality
1338 administration and quality control.
1339
1340 Quality administration refers to the management aspect of a quality assurance program. It
1341 includes those organizational steps taken to make sure that testing techniques are properly
1342 performed and that the results of tests are used to effectively maintain a consistently high level of
1343 image quality. An effective program includes assigning personnel to determine optimum testing
1344 frequency of the imaging devices, evaluate test results, schedule corrective action, provide
1345 training, and perform ongoing evaluation and revision of the quality assurance program.
1346
1347 Quality control comprises the procedures used for the routine physical testing of the primary
1348 components of the imaging chain from the x-ray source, through processing, to the viewing of
1349 images, as addressed in Table 1. Each facility, through its radiation quality control team (e.g.
1350 qualified physicist and biomedical maintenance personnel), needs to track maintenance and
1351 monitoring procedures.
1352
1353 Each facility performing medical imaging with x-rays should establish in writing and implement
1354 a technical quality assurance, quality administration, and quality control program that conforms
1355 to the most recent version of the "ACR Technical Standard for Diagnostic Medical Physics
1356 Performance Monitoring of Radiographic and Fluoroscopic Equipment" (ACR 2006b) and the
1357 "ACR Technical Standard for Diagnostic Medical Physics Performance Monitoring of Computed
1358 Tomography (CT) Equipment" (ACR 2007b). The program should include all aspects of the
1359 imaging process from image acquisition through image display. For film-screen imaging, it
1360 should include film and chemical expiration dates and storage requirements, monitoring of film
1361 processing, dark-room conditions, cleaning of intensifying screens, the cleaning and performance
1362 of view boxes, the ambient viewing conditions in rooms used for image interpretation, and image
1363 repeat analysis. For imaging with solid state image receptors such as computed radiography and
1364 direct radiography, it should include testing calibration of the CR plate readers and direct digital
1365 detectors, cleaning and inspection of CR plates, image repeat/reject analysis, calibration of
1366 detector exposure indices, monitoring of doses to the image receptors(exposure indices),
1367 uniformity of the sensitivity of the image receptor inventory, cleaning and monitoring of the
1368 luminance and calibration of video monitors used for initial image QC and interpretation, and the
1369 ambient viewing conditions in rooms used for image interpretation. Monitors for interpretation
1370 of grayscale images should be calibrated to the DICOM Grayscale Standard Display Function
1371 (NEMA 2009). These quality assurance measures are addressed in the Radiography section
1372 under Testing and Quality Assurance.
1373
1374 TECHNIQUE FACTORS
1375
1376 Technique factors should be established for each imaging procedure. For radiographic
1377 examinations, these include kV, mAs and exposure time if automatic exposure control is not
1378 used, and perhaps choice of image receptor. For CT examinations, these include kV, mA,
23
-------
DRAFT PROPOSAL
1379
1380
1381
1382
1383
1384
1385
1386
1387
1388
1389
1390
1391
1392
1393
1394
1395
1396
1397
1398
1399
1400
1401
1402
1403
rotation speed, pitch, selection of a mode in which mA is modulated during the scan (if
available), and degree of noise reduction (if available). Technique factors may be programmed
into the imaging device, or they may be manually selected. If they are programmed in,
programming should be consistent across all similar devices at a facility. Technique factors
should be chosen that produce a clinically-adequate image at the least dose to the patient, not an
ideal image. Whenever possible, technique factors should be adjusted to the thickness of the
patient.
If the review of technique factors used clinically or the comparison of dose indices indicates that
an optimum balance has not been achieved between patient dose and image quality or that
patient doses exceed national standards, the technique factors, whether posted in a chart or
programmed into the imaging device, and/or selection of image receptor, should be modified as
necessary.
TESTING BY A QUALIFIED PHYSICIST
It is strongly recommended that the technical quality assurance program includes testing by a
qualified physicist of all imaging equipment producing x-rays. The equipment should be tested
after installation but before first clinical use, annually thereafter, and after each repair or
modification that may affect patient dose or image quality. Testing after repair or modification
should be performed before clinical use of the equipment. The testing, including a summary of
methods, instruments used, measurements and deficiencies identified, should be documented in a
written report signed by the qualified physicist. The testing should include the items in Table 1
below:
Table 1. Testing Frequency of Imaging Equipment that Produces X-Rays
TASK
Measure radiation output parameters, including
beam intensity and beam quality
Test modes of operation used clinically, such as
automatic control systems (e.g., automatic
exposure controls of radiograph! c systems,
automatic exposure rate controls of fluoroscopy
systems.)
Assess image quality
Determine Detector Exposure Index Accuracy
(b)
Evaluate the accuracy of patient dose or dose
rate indicators
Assess the typical patient dose delivered for
various examinations for comparison to national
reference levels
Perform an acceptance test
INITIAL
X
X
X
X
X
X
X
AFTER
MODIFICATION
OR REP AIR (a)
X
X
X
X
X
X
X
ANNUAL
X
X
X
X
X
X
24
-------
DRAFT PROPOSAL
Table 1. Testing Frequency of Imaging Equipment that Produces X-Rays
TASK
Review the overall technical quality control
program
Perform a periodic review of all CT protocols (c)
INITIAL
X
AFTER
MODIFICATION
OR REP AIR (a)
ANNUAL
X
X
(a) Testing following repairs or modifications may be limited to features and parameters that
would be affected by the repairs or modification.
(b) Determine accuracy of detector exposure indices according to AAPM TGI 16 methodology
(AAPM 2009) and manufacturer's recommendations if available.
(c) The review of CT protocols should be performed together by the radiologist, CT technologist,
and medical physicist. Consider staggering annual reviews throughout the year to maintain
momentum without impacting schedules.
1404
1405
1406
1407
1408
1409
1410
1411
1412
1413
1414
1415
1416
1417
1418
1419
1420
1421
1422
1423
1424
1425
1426
1427
1428
1429
1430
1431
1432
1433
1434
1435
The qualified physicist may be assisted by other properly trained persons in obtaining test data
for performance monitoring. These persons should be trained by the qualified physicist in the
techniques for performing the tests, the function and limitations of the imaging equipment and
test instruments, the reasons for the tests, and the importance of the test results. The qualified
physicist should be present at the facility for the initial and annual testing and should promptly
review, interpret, and approve all data measurements and test results.
EQUIPMENT FAILURE
When x-ray imaging equipment fails to meet the performance specifications, the equipment
should be promptly adjusted or repaired to correct the deficiency or should be removed from
clinical use. A written or electronic record should be kept of the correction of such deficiencies
in accordance with the organization's record keeping policy. The record should include the date
of correction and the action taken to correct the deficiency.
DEFICIENCY CORRECTION VERIFICATION
After correction of deficiencies that affect patient dose or image quality, the equipment should be
tested promptly, by or under the supervision of a qualified physicist, to verify that the deficiency
was corrected and that the correction did not cause other deficiencies.
DOSIMETRY
Patient dose indices, measured at clinically-used technique factors by or under the supervision of
a qualified physicist, should be available for review. For radiography, entrance skin exposures
for common projections should be listed for a patient of typical thickness. For fluoroscopy
systems that have appropriate dosimetry measurement capabilities (e.g., air kerma or dose area
product), the accuracy should be measured and recorded. For fluoroscopy systems that do not
have dosimetry indicators, the typical and maximal entrance skin exposure estimates should be
measured and recorded for each fluoroscopic mode of operation for small, average, and large
patient thicknesses.
25
-------
DRAFT PROPOSAL
143 6 REFERENCE LEVELS
1437
1438 The primary purpose of an imaging study using ionizing radiation is to answer a clinical question
1439 or assist in making a diagnosis. Production of such a study results in two determinants: the
1440 qualitative evaluation by the health professional of the clinical value of the study, and the amount
1441 of radiation exposure required to conduct it. Each study should be evaluated for acceptable
1442 quality by a qualified individual (technologist or Radiological Medical Practitioner). A
1443 representative sampling and assessment of exposure indicators from each modality should be
1444 performed at least annually, but preferably quarterly, by a radiologic technologist under the
1445 guidance of a qualified physicist.
1446
1447 Reference levels (RLs) are values used as quality assurance and quality improvement tools.
1448 Quality improvement uses quantitative and qualitative methods to improve the safety,
1449 effectiveness, and efficiency of health care delivery processes and systems. Left unchanged, a
1450 system will produce the same results it has been achieving or degenerate. To achieve a higher
1451 level of performance, the system must be changed.
1452
1453 RLs were first introduced in the 1990s (ICRP 2003; Wall and Shrimpton 1998). RLs are used to
1454 help avoid radiation dose to the patient that does not contribute to the medical imaging task
1455 (ICRP 2003). They are intended to provide guidance on what is achievable with current good
1456 practice rather than optimum performance, and help identify unusually high radiation doses or
1457 exposure levels (ACR 2008b; IAEA 1996). RLs are a guide to good practice, but are neither
1458 dose limits nor thresholds that define competent performance of the operator or the equipment
1459 (Vafio and Gonzalez 2001). For assessments where the dose metric is determined using a
1460 phantom, a value above the reference level requires investigation. On the other hand, for
1461 interventional procedures, if the mean dose metric for a number of cases of a procedure exceeds
1462 the reference level, it does not always mean that the procedure has been performed improperly.
1463 Similarly, a mean dose metric for a procedure that is less than the reference level does not
1464 guarantee that the procedure is being performed optimally (Vafio and Gonzalez 2001).
1465
1466 These levels are based on exposure to a standard phantom or actual patient dose metrics for
1467 specific procedures measured at a number of representative clinical facilities. RLs are set at
1468 approximately the 75th percentile (third quartile) of these measured data. The use of RLs is
1469 supported by national and international advisory bodies (Amis et al. 2007; ICRP 2000a). These
1470 and other organizations have provided guidelines on measuring radiation dose metrics and
1471 setting reference levels (IAEA 1996; ICRP 1991a; ICRP 1996; ICRP 2007c; Wall and Shrimpton
1472 1998). RLs can be specific to the country or region, and may be derived from multinational,
1473 national or local data (ICRP 2003; ICRP 2007b). As of 2012, U.S. reference levels are not
1474 available for most imaging studies. In order to generate national RLs for the U.S., it is essential
1475 that institutions where these procedures are performed submit radiation dose metrics to a central
1476 dose registry.
1477
1478 Each institution or individual practitioner should use reference levels as a quality improvement
1479 tool by collecting and assessing radiation dose data. Standard phantoms are used where the
1480 procedure is standardized (e.g., chest radiograph or head CT). Patient dose metric data are
1481 collected if the procedure is individualized for each patient (such as fluoroscopically guided
26
-------
DRAFT PROPOSAL
1482 interventions) and should be collected for standardized procedures as well. The mean radiation
1483 dose for the examination is then compared to the reference level for that examination (ICRP
1484 2003). If the mean radiation dose at the facility exceeds the reference level, equipment and
1485 clinical practices should be investigated in order to reduce radiation doses (NRPB 1990; Wall
1486 2001). Equipment function should be investigated first, followed by review of the clinical
1487 protocol (Vano and Gonzalez 2001). Investigations are also appropriate where local values are
1488 substantially below the RLs, as excessively low doses may be associated with poor image quality
1489 (Baiter et al. 2008; IAEA 2009). As appropriate, operator performance may be assessed if no
1490 other cause is found. The development of reference levels requires consideration of the
1491 technique factors which most affect patient exposure. The Nationwide Evaluation of X-ray
1492 Trends (NEXT) is a program conducted by the Food and Drug Administration (FDA) in
1493 conjunction with the States and the Conference of Radiation Control Program Directors
1494 (CRCPD) (FDA 201 Oa). The NEXT data provide a profile of aspects of medical and dental
1495 imaging using ionizing radiation in the United States at the time of survey. These data provide a
1496 window into clinical practice because they reflect the myriad of combinations of imaging
1497 equipment, technique factors, and the skills of equipment operators. Therefore, regardless of the
1498 specific details of technique or combinations of all these factors, the frequency distributions of
1499 dose derived from the NEXT data were assumed to be sufficiently representative of the complex
1500 interaction of Referring Medical Practitioner preference, Radiological Medical Practitioner
1501 preference, operator technique, and x-ray equipment performance for each of the selected
1502 standard examinations. Thus, NEXT data, when available and current, serve as a useful source
1503 for the development of national reference lev els in the U.S. (ACR2008b).
1504
1505 Professional organizations in the U.S., such as the American College of Radiology (ACR 2008b)
1506 and the American Association of Physicists in Medicine (Gray et al. 2005), support the use of
1507 third quartile values of particular dose indices. It is important, however, to emphasize that with
1508 good technique, practicable levels of exposure for most patients will be below these levels.
1509
1510 The ICRP considers RLs a useful tool to help optimize patient radiation dose in fluoroscopically
1511 guided interventional (FGI) procedures (ICRP 2007c). As of 2012, some studies have presented
1512 RLs for cardiovascular procedures (Baiter et al. 2008; D'Helft et al. 2009; Neofotistou et al.
1513 2003; Peterzol et al. 2005) and a limited number of interventional radiology procedures (Aroua
1514 et al. 2007; Brambilla et al. 2004; Hart et al. 2009; Miller et al. 2009; Tsalafoutas et al. 2006;
1515 Vano et al. 2008a; Vano et al. 2009; Vano et al. 2008b; Verdun et al. 2005). Unfortunately, the
1516 observed distributions of patient doses for most types of FGI procedures are very wide, because
1517 the dose for each instance of a procedure is strongly dependent on individual clinical
1518 circumstances. A potential approach is to include the ' complexity' of the procedure in the
1519 analysis (Baiter et al. 2008; IAEA 2009; ICRP 2007c). Since, as of 2012, complexity cannot be
1520 quantified (with the exception of some interventional cardiology procedures), this adjustment is
1521 not possible for FGI procedures (Baiter et al. 2008; IAEA2009). Because of the high individual
1522 variability of patient dose in cases of FGI procedures, the number of cases recommended in the
1523 literature as sufficient to provide adequate radiation dose data for a single facility varies from 10
1524 to >50 (Vano et al. 2008a; Wall and Shrimpton 1998).
1525
1526 It is expected that U.S. reference levels will decrease over time as outlier institutions improve
1527 their equipment and practices. In the United Kingdom, reference levels derived from data in the
-------
DRAFT PROPOSAL
1528 2000 review were approximately 20% lower than those derived from data in the 1995 review and
1529 approximately half of those determined in the mid-1980s (Hart et al. 2009).
1530
1531 For each type of examination there exists, within available technology, an optimal combination
1532 of imaging equipment and technique factors to produce adequate images at doses below the
1533 reference level. Hence, it is important to evaluate each system's performance to determine
1534 whether dose is optimized and to maintain this by establishing appropriate procedures and
1535 conducting periodic monitoring.
1536
1537
1538 GUIDANCE BY DIAGNOSTIC AND INTERVENTIONAL MODALITY
1539
1540 INTRODUCTION
1541
1542 Except in emergency situations, informed consent should be obtained from the patient or the
1543 patient's legal representative and appropriately documented prior to the initiation of any
1544 procedure that is likely to expose the patient, or fetus if the patient is pregnant, to significant
1545 risks and potential complications. When obtaining informed consent for image-guided
1546 procedures using ionizing radiation that are known to be potentially high dose, an estimation of
1547 the anticipated risks from the radiation dose should be communicated to the patient as part of the
1548 overall discussion of risks (NCRP 2010). When a delay in treatment would jeopardize the health
1549 of a patient and informed consent cannot be obtained from the patient or the patient's legal
1550 representative, an exception to obtaining informed consent is made (ACR 2006a).
1551
1552 Once the physician or dentist determines that the prescription of an x-ray examination is
1553 warranted for diagnostic purposes, other factors become important in limiting patient exposure.
1554 Optimization of patient dose may not be accomplished, even when well-designed equipment is
1555 used, unless appropriate quality assurance programs exist to keep it functioning properly and
1556 those who operate it are properly qualified to use the features of the equipment. These latter
1557 considerations are discussed in the chapter on Technical Quality Assurance in Medical Imaging
1558 with X-Rays. To ensure that x-ray equipment used is justifiably representative of present day
1559 technological advances, authorities should develop and periodically review a planned
1560 replacement schedule for all types of diagnostic x-ray equipment used in their programs.
1561
1562 All x-ray equipment used for the imaging of humans for medical purposes should be maintained
1563 so that it conforms, throughout its useful lifetime, to applicable FDA regulations (FDA 2012g).
1564 Furthermore, users should be aware of upgrades to software and hardware that enhance safety.
1565 These should be evaluated and considered for implementation.
1566
1567 The qualifications of x-ray imaging equipment operators should be defined by the responsible
1568 authority in a written protocol which details: 1) who may operate x-ray imaging equipment and
1569 the supervision required, 2) the education, training, and proficiency requirements for x-ray
1570 imaging equipment operators, and 3) requirements for continuing education and demonstration
1571 of proficiency. This policy should be reviewed and revised as required.
1572
1573 Prior to each examination requiring ionizing radiation, there should be a pre-procedure
28
-------
DRAFT PROPOSAL
1574 "verification" that patient identity, intended procedure and positioning, and equipment are
1575 correct. Also, the technologist should confirm that the patient, if female, is not pregnant and
1576 that, if contrast media is to be used, the patient is not allergic to it. Invasive procedures and CT
1577 examinations require both pre-procedure "verification" and "time-out" processes. Those
1578 processes should be as specified by The Joint Commission for invasive procedures under the
1579 Universal Protocol (The Joint Commission 2012a; The Joint Commission 2012b).
1580
29
-------
DRAFT PROPOSAL
1581 RADIOGRAPHY
1582
1583 General radiography is a service usually provided by a Radiology Department, either in a central
1584 department or satellite facilities. Requests (orders) for general radiography services are
1585 performed based on protocols for standard views of each anatomic area, modified, if needed, to
1586 suit special requests or circumstances. Authorized variations to these protocols should be made
1587 for patient age and body habitus. Each medical center should have a written policy for the safe
1588 use of radiograph!c equipment. This policy should apply to all radiographic equipment, whether
1589 fixed or portable. This policy should:
1590
1591 1. require testing of the radiographic equipment by a qualified physicist (or under their
1592 guidance for facilities or locations where it is not practicable to provide such staffing),
1593 2. require training and credentialing of persons operating or directing the operation of
1594 radiographic equipment, and
1595 3. specify procedures for the safe use of the equipment, including dose management and
1596 recordkeeping.
1597
1598 Equipment
1599
1600 Beginning in the 1990s, a transition occurred from film-screen radiography to digital
1601 radiography (radiography using other image receptors). These newer image receptor
1602 technologies include storage phosphor plates and several direct-image-capture technologies. All
1603 of these digital radiography technologies produce digital images that are most commonly viewed
1604 on video monitors, although the images may be printed on film using a laser printer, chemically
1605 developed, and examined on a view box.
1606
1607 With film-screen radiography, there is feedback to the technologist if technique factors, primarily
1608 mAs, result in an excessive exposure to the patient. The pertinent measure of the response to
1609 radiation exposure is the optical density of the film. Optical density is a non-linear function of
1610 radiation exposure. In film-screen radiography, when imaging a specific projection of a
1611 particular patient, only a narrow range of patient exposures will produce an adequate image. An
1612 exposure greater than this range produces an "overexposed" film with excessive optical density
1613 and inadequate image contrast, and an exposure below this range produces an "underexposed"
1614 film with excessively low optical densities and inadequate image contrast. Thus, provided that
1615 an appropriate x-ray tube voltage is used and the film is properly developed, the choice of film-
1616 screen combination largely determines the radiation exposure to a patient of a given size.
1617
1618 There are advantages and disadvantages to digital image receptors in comparison to film-screen
1619 receptors. Digital receptors respond to radiation over a wide range of exposures. The statistical
1620 noise in the image varies with the exposure, with higher exposures producing images with
1621 relatively less statistical noise. One of the many advantages is that the wide range of exposures
1622 permits the exposure for a particular image to be matched to the clinical task - for an imaging
1623 procedure in which more statistical noise can be tolerated, a lower exposure can be used.
1624 Another advantage is that images acquired with overly high exposures and some of those
1625 acquired with overly low exposures may still be useful, avoiding retakes. An image acquired
30
-------
DRAFT PROPOSAL
1626 with an excessively low exposure will have excessive statistical noise, but this may not render
1627 the image uninterpretable.
1628
1629 There are also disadvantages to digital radiography. Digital image receptors facilitate acquiring
1630 multiple images, which may encourage the acquisition of more images than are clinically
1631 necessary. As of 2012, radiography with storage phosphor plates may require significantly
1632 larger patient exposures, by a factor of 1.5 to 2, than rare-earth phosphor film-screen systems to
1633 produce images of equivalent quality (Compagnone et al. 2006; Seibert et al. 1996). In digital
1634 radiography, an excessive exposure decreases statistical noise and will likely produce an image
1635 that is of higher quality than needed for the clinical task. Furthermore, it may not be apparent to
1636 either the technologist or the Radiological Medical Practitioner that the exposure was excessive.
1637 Thus, there may be a tendency for technologists to routinely use unnecessarily high exposures, a
1638 phenomenon called "dose creep" or "exposure creep" (Freedman et al. 1993; Seibert et al. 1996;
1639 Willis and Slovis 2005). Excessive exposures are especially likely when using manually selected
1640 technique factors instead of automatic exposure control. Examinations made using storage
1641 phosphor plates and mobile radiographic machines are particularly susceptible to excessive
1642 exposures. Excessive exposures can also occur due to improper calibration of the automatic
1643 exposure control system, the incorrect configuration of protocols, or the use of an inappropriate
1644 protocol when automatic exposure control is used. Deliberate use of a protocol that provides an
1645 excessive exposure to avoid retakes or criticisms due to underexposure should be avoided.
1646
1647 Testing and Quality Assurance
1648
1649 Quality assurance measures for radiographic imaging using film-screen image receptors are well
1650 established, and are described in several publications (AAPM 2006b; ACR 2006b; NCRP
1651 1989b). These measures include, among others, cleaning of image intensifying screens;
1652 establishing technique charts for exposures; and monitoring film processing, darkroom
1653 conditions, film storage, retakes, inadequate images, view boxes, and viewing conditions.
1654 Digital radiography retains some of the quality assurance issues seen with film screen image
1655 receptors, eliminates others, and adds new ones (AAPM 2005; AAPM 2006a; ICRP 2004).
1656
1657 Storage phosphor image receptor systems and many direct image capture systems provide the
1658 capability to monitor the exposure to the image receptor from each individual imaging exposure,
1659 with a quantity termed the exposure indicator. The exposure indicator relates to receptor
1660 exposure, and not directly to patient dose. As of 2012, each manufacturer of these systems
1661 defines, calculates, and names their exposure indicator differently. These proprietary exposure
1662 indicators are not consistent. Some are proportional to the exposure and others are proportional
1663 to the logarithm of the exposure. Some increase as the exposure to the image receptor increases
1664 and others decrease as the exposure increases. A standard indicator of exposure to the image
1665 receptor (called the Exposure Index) for adoption by all manufacturers was developed and
1666 published in 2009 and adopted by the International Electrotechnical Commission (AAPM 2009;
1667 IEC 2008). Each facility should have a program for monitoring indices of exposure to image
1668 receptors, and work toward adopting the standard index when feasible after it is adopted.
1669 Facilities should work with their Radiological Medical Practitioners and qualified physicists to
1670 develop procedures and establish target Exposure Index values and respective Deviation Index
1671 ranges by category of examination and patient population.
31
-------
DRAFT PROPOSAL
1672
1673 Quality assurance measures should be adopted for digital radiography (ACR 2007a). Table 2
1674 below in the procedures section lists these measures.
1675
1676 It is strongly recommended that radiographic technique factors be established for common
1677 procedures. These either should be programmed into the x-ray machine or a technique chart
1678 should be immediately available to the operator. Because of the phenomenon of dose creep, the
1679 use of appropriate technique factors is especially important in digital radiography. The technique
1680 factors for imaging protocols should be optimized for the age and size of the patient, and for the
1681 imaging task. Although a qualified physicist can assist with this process, protocol optimization
1682 also requires the efforts of a Radiological Medical Practitioner. This process can benefit from
1683 the involvement of a technologist and the vendor, as well. It is particularly important to optimize
1684 the technique factors for radiographic imaging protocols performed on infants and children since
1685 the preset vendor protocols may result in unnecessary radiation dose.
1686
1687 Pediatric imaging imposes additional concerns. It is strongly recommended that particular
1688 attention be paid to dose optimization for pediatric patients. For pediatric patients the operator
1689 should determine the need for an anti-scatter grid (if removable) and patient immobilization.
1690 Collimation should be adjusted appropriately and technique charts should be used for those body
1691 parts that do not cover the sensor of the automatic exposure control device.
1692
1693 Personnel
1694
1695 Each person who directs the operation or operates radiographic equipment should be trained in
1696 the safe use of radiographic equipment, in order to ensure adequate image quality and optimize
1697 patient dose. Also see the section on PERFORMING AND SUPERVISING STUDIES:
1698 RADIOLOGICAL MEDICAL PRACTITIONERS AND TECHNOLOGISTS.
1699
1700 Radiological Medical Practitioner
1701
1702 Radiographic equipment should be operated under the general supervision of a physician. This
1703 individual fulfills the responsibilities of the Radiological Medical Practitioner. Depending on the
1704 study, the responsible physician may be a radiologist, a surgeon, a cardiologist, a
1705 gastroenterologist, or another medical specialist. This individual should be appropriately trained
1706 in the imaging modality, should be familiar with the principles of radiation protection, and
1707 should have a sufficient understanding of the medical imaging modality's features to determine
1708 the appropriate protocol to evaluate the patient's clinical symptoms.
1709
1710 Technologist
1711
1712 The technologist is responsible for using facility-approved imaging protocols and radiation
1713 protection measures. Technologists should be trained to produce adequate quality radiographic
1714 images and to assist in the quality assurance program. They should also be able to optimize
1715 various technique factors of the x-ray equipment to produce an adequate radiographic image at
1716 the lowest practicable patient dose and to use optimal procedures in working with patients and
1717 ancillary equipment to reduce to a minimum the number of repeat examinations. Some operators
32
-------
DRAFT PROPOSAL
1718 have little or no formal training in anatomy, patient positioning, or radiation protection practices.
1719 Performance of x-ray examinations by these inadequately trained individuals is not justified
1720 except for emergencies.
1721
1722 Other personnel
1723
1724 Only personnel with specific, appropriate training should be permitted to operate x-ray
1725 equipment. The use of x-ray equipment by other individuals is warranted only in an urgent or
1726 emergent situation when qualified personnel as specified above are not available to perform the
1727 examination in a timely fashion.
1728
1729 Procedures
1730
1731 It is strongly recommended that a radiologist provide general supervision in facilities performing
1732 radiography. Aboard certified radiologist is preferred. Periodic review of the radiograph! c
1733 images should be performed as part of the routine quality assurance process.
1734
1735 X-ray examinations should be performed in accordance with approved imaging protocols. The
1736 technologist should not perform any examination which has not been requested by an authorized
1737 person.
1738
1739 Collimation restricts the useful beam to the clinical area of interest. Collimation to exclude body
1740 areas not being examined should be used to minimize unnecessary exposure. Masking portions
1741 of a digital image is not a substitute for collimation.
1742
1743 If it does not interfere with the examination, contact or shadow shielding, using leaded aprons or
1744 other shields, should be employed to shield those parts of the patient that are particularly
1745 radiosensitive and are within the primary beam. Gonadal shielding should be used as
1746 appropriate. It is strongly recommended that breast shielding be used for scoliosis examinations
1747 on girls and young women. All shields should be placed between the x-ray source and the tissue
1748 to be shielded. When shielding is used, an automatic exposure control sensor should be selected
1749 that is not within the shadow of the shield, or manual exposure control should be used.
1750
1751 A written outline containing the minimum number of views to be obtained and the equipment to
1752 be used for each requested examination should be made available to each Radiological Medical
1753 Practitioner and equipment operator in every radiology facility. Beyond the specified minimum
1754 views, the examination should be individualized according to a patient's needs.
1755
1756 The outline of procedures should indicate who may authorize deviations from the standard set of
1757 views for any examination. Every effort should be made to reduce to a minimum the number of
1758 standard views for any examination. The necessity of additional views, such as comparison
1759 views, should be determined by the Radiological Medical Practitioner.
1760
1761 A periodic review of all standard examination procedures should be performed to determine if
1762 the established routine is achieving the objectives and whether modifications are warranted.
33
-------
DRAFT PROPOSAL
1763
1764
1765
1766
1767
1768
1769
1770
1771
1772
1773
1774
1775
1776
1777
1778
1779
1780
Continuation of a standardized examination procedure should be predicated on satisfying the
following criteria:
1. the efficacy of the examination is sufficiently high to assure that the diagnosis could not
have been made with less risk by other non-radiological means or a smaller number of
views,
2. consideration of previous similar examinations performed with multiple views established
that in a significant number of the cases all views were necessary for the diagnoses
rendered, and
3. the yield or outcome of the examinations offsets the radiation exposure delivered.
A periodic review should be performed at least annually by experts designated by departmental
leadership, and with the input of referring physicians. These reviews should consider applicable
regulations as well as the consensus and advice of professional societies concerning the efficacy
of radiologic examinations.
Other quality assurance measures are listed in Table 2 below. The specifics of these measures
may change over time. The user should consult the relevant AAPM testing protocols.
Table 2. Quality Assurance Measures for Film and Digital Modalities
Film-Screen
Radiography
Task
Physicist testing
Processor Monitoring
Darkroom Cleaning
Processor Preventive
Maintenance
Screen Cleaning
Repeat Analysis
Darkroom Fog
Film-Screen Contact Test
Review Local Radiation
Protection and Quality
Control Operating
Instructions
Frequency
See Table 1
Daily
Weekly
Monthly
Monthly
Quarterly
Annually
Annually
Annually
Methodology
See section on Technical Quality Assurance in Medical
Imaging with X-Rays.
Clean crossover racks and perform sensitometry test.
Check for dust, clutter, etc.
Perform deep cleaning and evaluate darkroom chemicals as
recommended by the manufacturer.
Clean all screens in inventory according to manufacturer' s
recommendations
Track the repeat/reject rate and ensure it is less than or
equal to 7% (NCRP 1988). Trends indicating deterioration
in performance or increase in patient dose should be
investigated.
Lightly expose a film (image a step wedge at 70 kVp, 5
mAs). In the darkroom with safelight on, cover half the
latent image with an opaque material for at least 2 minutes
then develop the film. A visible line between the two parts
of the image indicates a darkroom fog problem.
Follow film-screen contact test tool instructions.
Revise as needed.
34
-------
DRAFT PROPOSAL
1781
Computed Radiography
Task
Physicist testing
Image Plate Erasure
Quality Control Phantom
Image Acquisition
Transmit Phantom Image
to Interpreting Medical
Treatment Facility (MTF)
Operator Console
Repeat Analysis
Dose Monitoring
Detector Exposure Index
Monitoring
Image Plate Inspection
and Cleaning
Review Local Radiation
Protection and Quality
Control Operating
Instructions
Frequency
See Table 1
Weekly, or
daily if
unsure of
status
Monthly
Monthly
At least
Monthly
Quarterly
Quarterly
Quarterly
Quarterly
Annually
Methodology
See section on Technical Quality Assurance in Medical
Imaging with X-Rays.
Perform primary erasure of each plate following
manufacturer' s instructions. This should be performed
before use if the status of the plate is unknown or fogging is
anticipated. Plates in storage do not require erasing until
used (AAPM 2006a).
Follow manufacturer's recommendations.
For Teleradiology Sites Only: After acquisition of QC
image, transmit to interpreting MTF for verification of
image quality.
View and evaluate QC pattern (AAPM 2005), clean
monitors.
Track the repeat/reject rate and ensure it is less than or
equal to 7% (NCRP 1988). Trends indicating deterioration
in performance or increase in patient dose should be
investigated.
Review patient dose indices according to manufacturer's
recommendations.
Review exposure indicators according to AAPM TGI 16
methodology (AAPM 2009) and compare with guidance
levels. One source for appropriate guidance levels may be
the manufacturer.
Follow manufacturer's recommendations for proper
cleaning technique using approved cleaning solution and
proper safety precautions.
Revise as needed.
1782
Direct Digital
Radiography
Task
Physicist testing
Quality Control Phantom
Image Acquisition
Operator Console
Frequency
See Table 1
Weekly
At least
Monthly
Methodology
See section on Technical Quality Assurance in Medical
Imaging with X-Rays.
Follow manufacturer's recommendations.
View and evaluate QC pattern (AAPM 2005), clean
monitors.
35
-------
DRAFT PROPOSAL
Direct Digital
Radiography
Task
Transmit Phantom Image
to Interpreting MTF
Repeat Analysis
Dose Monitoring
Detector Exposure Index
Monitoring
Review Local Radiation
Protection and Quality
Control Operating
Instructions
Frequency
Monthly
Quarterly
Quarterly
Quarterly
Annually
Methodology
For Teleradiology Sites Only: After acquisition of QC
image, transmit to interpreting MTF for verification of
image quality.
Track and trend the repeat/reject rate and ensure it is less
than or equal to 7% (NCRP 1988).
Review patient dose indices according to manufacturer's
recommendations.
Review exposure indicators according to AAPM TGI 16
methodology (AAPM 2009) and compare with guidance
levels. One source for appropriate guidance levels may be
the manufacturer.
Revise as needed.
1783
Interpretation and QC
Display Monitors
Task
User task: Visual
assessment using QC test
pattern
Physicist, technologist
tasks: Display system
performance
Physicist tasks: display
system calibration
verification
Monitor cleaning
Frequency
Daily
Monthly/
Quarterly
Initially
and
Annually
Monthly
and as
needed
Methodology
AAPM TG-18 Online Report 3, table 8a or equivalent
(AAPM 2005)
AAPM TG-18 Online Report 3, table 8b or equivalent
(AAPM 2005)
AAPM TG-18 Online Report 3, table 8c, or equivalent
(AAPM 2005)
Clean monitors with cleaner approved by manufacturer
1784
178f
178(
178'
Other External
Equipment
Task
Printer quality control
Digitizer quality control
Frequency
See
methodology
See
methodology
Methodology
Follow manufacturer's recommendations
Follow manufacturer's recommendations
1
36
-------
DRAFT PROPOSAL
1788 FLUOROSCOPY
1789
1790 Fluoroscopy may be employed by a variety of services in a medical facility to guide procedures,
1791 including imaging. It can be performed with fixed, mobile or portable fluoroscopy systems.
1792 Some fluoroscopically guided procedures can deliver a large radiation dose to the patient, even
1793 when used properly. Prolonged procedures may result in injury, including non-healing ulcers,
1794 and other tissue injuries (FDA 1994). Because staff must remain with the patient in the
1795 procedure room during fluoroscopy, their potential occupational radiation dose is non-trivial.
1796 Each medical center should have a written policy for the safe use of fluoroscopic equipment.
1797 This policy should apply to all fluoroscopy equipment, whether fixed, mobile, or portable, e.g.,
1798 mobile C-arm systems and mini C-arm systems. This policy should
1799
1801
1802
1803
1804
1799
1800 1. require testing of the fluoroscopic equipment by or under the direction of a qualified
iRfll physicist,
2. require training and credentialing of persons operating or directing the operation of
fluoroscopic equipment,
^ ~_ . 3. specify procedures for the safe use of the equipment, including dose management and
1805 recordkeeping, and
1806 4. require a clinical QA/QI program for fluoroscopy.
1807
1808 Although the aggregate population effective dose is larger from the use of general purpose
1809 diagnostic equipment and CT, the highest organ doses (especially skin doses) to individuals,
1810 other than in radiation oncology, generally result from interventional fluoroscopic procedures.
1811 These procedures may require high exposure rates for long periods of time; thus, it is of utmost
1812 importance that Federal health care facilities give particular attention to fluoroscopic
1813 examinations. Even for simple and low-dose fluoroscopic examinations, proper training is
1814 required to perform the procedure with the optimal radiation dose. Therefore, x-ray equipment
1815 capability should not exceed the medical mission of the facilities, i.e., fluoroscopy should not be
1816 available in facilities where qualified medical personnel are not assigned. Equipment, physicians
1817 and staff should all meet current guidelines of the American College of Radiology Technical
1818 Standard for Management of the Use of Radiation in Fluoroscopic Procedures and its successors
1819 (ACR2008c).
1820
1821 Equipment requirements and training requirements for operators differ depending on whether the
1822 procedures to be performed will be relatively low dose or potentially high dose.
1823 Fluoroscopically guided procedures should be classified as potentially high radiation dose if
1824 more than 5% of cases of that procedure result in an air kerma at the interventional reference
1825 point exceeding 3 Gy or a kerma-area product (KAP) exceeding 300 Gy-cm2. Low dose
1826 procedures are below these levels (NCRP 2010).
1827
1828 Equipment
1829
1830 If the medical mission requires fluoroscopy, only image-intensified units (with image intensifiers
1831 or flat panel detectors) should be used. As of mid-2006, all fluoroscopic equipment sold in the
1832 United States provides a final indication of air kerma (proportional to radiation dose) at a
1833 reference point at the completion of the examination. This simplifies the process of measuring
37
-------
DRAFT PROPOSAL
1834 and recording radiation dose in the medical record.
1835
1836 Some operative procedures, both minimally invasive and open surgical, performed both inside
1837 and outside the operating room, (e.g., hip replacement, transsphenoidal hypophysectomy, some
1838 endoscopic procedures) may require fluoroscopic assistance. In general, these procedures tend to
1839 be relatively low-dose. For these procedures, to the fullest extent practicable, only equipment
1840 with features such as last-image-hold and reduced dose pulsed fluoroscopy, or equipment with
1841 similar dose-reducing features, should be used. The advantage of this technology is that the
1842 radiation exposure can be reduced compared to continuous fluoroscopy, while adequate image
1843 quality is maintained.
1844
1845 For procedures with a potential for high patient doses (this includes most interventional
1846 radiology, interventional cardiology, interventional neuroradiology and endovascular surgical
1847 procedures), additional requirements apply for both equipment and personnel (Hirshfeld et al.
1848 2004; Lipsitz et al. 2000; Miller et al. 2003a; Miller et al. 2003b; Padovani and Quai 2005;
1849 Suzuki et al. 2006). Fluoroscopy equipment intended for these procedures should, at a
1850 minimum, be compliant with the version of International Electrotechnical Commission Standard
1851 60601-2-43 (IEC 2010) applicable to the equipment at the time of purchase. New fluoroscopic
1852 imaging systems should incorporate high heat-loading tubes, adjustable-rate pulsed fluoroscopy
1853 capability, spectral shaping filters, and automatic exposure control logic to optimize radiation
1854 dose and ensure adequate image quality throughout the procedure. As future systems incorporate
1855 improved methods for both tracking and optimization of patient dose during fluoroscopically-
1856 guided procedures, purchasers and operators should take advantage of them when appropriate.
1857 The additional cost of dose-reduction technology is justified because the reduction in patient
1858 radiation dose can be considerable.
1859
1860 Proper patient management during fluoroscopically-guided interventions requires appropriate use
1861 of the various features of the fluoroscopic equipment. This will permit patient dose to be
1862 optimized and staff dose to be minimized. There is an extensive literature on this subj ect which
1863 can be used for guidance (Chambers et al. 2011; Miller et al. 2010a; NCRP 2010; Stecker et al.
1864 2009; Steele etal. 2012).
1865
1866 Measurement or estimation of skin dose is desirable for all procedures which are high dose or
1867 have the potential to result in high patient dose. The quantity of interest is the peak skin dose
1868 (PSD), the highest dose at any point on the patient's skin. This determines the severity of a
1869 radiation-induced skin injury. Ideally, equipment should also provide the operator with a near
1870 real-time indication of skin dose, including PSD in the current radiation field. The operator
1871 would then be able to modify his/her technique during the procedure to minimize skin dose
1872 (FDA 1994; Miller et al. 2002). Skin dose can be measured with special films, an array of
1873 thermoluminescent dosimeters (TLDs), optically stimulated luminescence (OSL) dosimeters or
1874 real-time point-measurement devices (Baiter et al. 2002). Currently, these methods are
1875 expensive, cumbersome and inconvenient, and are not commonly used in routine clinical
1876 practice. In the future, software-based systems should be able to estimate and map skin dose in
1877 real time.
1878
1879 Cumulative air kerma (cumulative air kerma at the reference point; also called reference point
38
-------
DRAFT PROPOSAL
1880 dose, reference air kerma, reference point air kerma, or cumulative dose) is measured in Gy and
1881 displayed automatically on all fluoroscopic equipment in the United States sold after mid-2006
1882 per 21CFR1020.32(k) (FDA 2012d). It is the dose at a pre-defined reference point. This point is
1883 separately defined for different types of fluoroscopic equipment (FDA2012d; FDA2012f). For
1884 C-arm units, this point is located along the central ray of the x-ray beam, 15 cm from the
1885 isocenter towards the x-ray source (TEC 2010). Cumulative air kerma is not the same as skin
1886 dose. Cumulative air kerma is measured at a point in space that is fixed with respect to the
1887 gantry and can move with respect to the patient when the table is moved or the gantry is angled.
1888 Cumulative air kerma does not take table height or these motions into account. As a result,
1889 reference dose is usually greater than PSD (IEC 2010; Miller et al. 2003a; Miller et al. 2012).
1890
1891 Kerma-area product (KAP, also called dose-area product or DAP) is the product of the air kerma
1892 and the area of the irradiated field and is measured in Gycm2. It does not change with distance
1893 from the x-ray tube. It is a good measure of the total energy delivered to the patient, and
1894 therefore a good measure of stochastic risk. It is not a good indicator of deterministic risk
1895 (Kwon et al. 2011; Miller et al. 2012).
1896
1897 Fluoroscopy time has been the standard dose metric. It is easy to measure and the capability to
1898 measure it is widely available. However, fluoroscopy time does not reflect the effects of
1899 fluoroscopic dose rate or the radiation dose from fluorography (e.g., digital subtraction
1900 angiography or cinefluorography) and is a poor indicator of patient dose. As recommended in a
1901 joint Society of Interventional Radiology/Cardiovascular and Interventional Radiological Society
1902 of Europe (SIR/CIRSE) guideline, use of fluoroscopy time as the sole dose metric is not
1903 advisable, and should not be done unless no other dose metric is available (Stecker et al. 2009).
1904 Even then, the number of images and cine frames should also be recorded. Procedures with a
1905 potential for high patient doses should not be performed using fluoroscopy equipment that is not
1906 compliant with IEC 60601 -2-43 or its successors (IEC 2010).
1907
1908 For patient care and for quality assurance purposes, it is highly desirable for all radiation data to
1909 be transferred automatically to the PACS (picture archiving and communication system), RIS
1910 (radiology information system), and Electronic Health Record (EHR) as part of the study data
1911 (along with images and demographic information) if the fluoroscopy unit is connected to a
1912 PACS. These data should include the peak skin dose, if available; the cumulative air kerma from
1913 both fluoroscopy and from image acquisition, if available; the kerma-area product, if available;
1914 and the cumulative fluoroscopy time and number of images or cine frames recorded (Miller et al.
1915 2012; NCRP 2010). The IHE REM integration profile provides a standard for the transfer of
1916 such information to the PACS ((ME 2008) or current version).
1917
1918 There are several relatively new technologies as of 2012 (e.g., cone-beam CT, surgical O-arms,)
1919 (ACR 2008c; Orth et al. 2008; Wallace et al. 2008). Others will certainly appear in future
1920 interventional fluoroscopy equipment. Some of these technologies are intended to provide
1921 greater technical capability for complex surgical or interventional procedures. Currently, most of
1922 these technologies are designed to enhance the fluoroscopy unit's surgical capability for
1923 procedures performed outside the Radiology Department. Mobile equipment with these
1924 technologies is smaller in size than its conventional fixed counterpart, but it can be just as
1925 dangerous to the operator and patient. Facilities should establish procedures for the testing and
39
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DRAFT PROPOSAL
1926 use of these types of equipment, and for the training and credentialing of its operators.
1927
1928 Testing and Quality Assurance
1929
1930 Equipment testing for quality assurance should be performed by or under the direction of a
1931 Qualified Physicist after installation but before first clinical use, annually thereafter, and after
1932 each repair or modification that may affect patient dose or image quality. Testing should be
1933 performed as specified in the section of this document entitled Technical Quality Assurance in
1934 Medical Imaging with X-Rays.
1935
1936 Personnel
1937
1938 Fluoroscopy can deliver a significant radiation dose to the patient, even when used properly.
1939 Also, fluoroscopy presents the potential for greater radiation dose to the operator as compared
1940 with other imaging modalities. Therefore, all fluoroscopic examinations should be performed by
1941 or under the direct supervision of a physician with demonstrated competence, who has received
1942 training in fluoroscopy and has been privileged by the facility to perform fluoroscopy.
1943
1944 In fluoroscopy, the operator effectively determines, prescribes and delivers the required x-ray
1945 dose to the patient in real-time. These systems are often used to guide imaging or interventions
1946 and the exposure is directly related to the complexity of the procedure and inversely related to
1947 the skill of the individual performing the procedure. Individuals who are privileged for the use
1948 of these systems, and particularly the high dose capable systems as are used in interventional
1949 procedures should have a thorough understanding of the biological effects of radiation exposure,
1950 the dose from this radiation exposure and its likely deterministic and stochastic risks, and of the
1951 available technique and technology based methods for minimizing the radiation dose to any
1952 portion of the patient's tissue during the examination.
1953
1954 Every person who operates or directs the operation of fluoroscopic equipment should be trained
1955 in the safe use of fluoroscopic equipment, in order to optimize patient dose. Initial training
1956 should include didactic training, hands-on training, and clinical operation under a preceptor.
1957
1958 Didactic training is a formal course of instruction in radiation safety which meets guidelines
1959 established by the responsible authority. It should include the following topics: (a) physics of x-
1960 ray production and interaction; (b) the technology of fluoroscopy machines, including modes of
1961 operation; (c) characteristics of image quality and technical factors affecting image quality in
1962 fluoroscopy; (d) dosimetric quantities, units, and their use in radiation management; (e) the
1963 biological effects of radiation; (f) principles of radiation protection in fluoroscopy, (g) applicable
1964 federal regulations and agency requirements; and (h) techniques for minimizing dose to the
1965 patient and staff. Completion of this phase of training should include successfully completing a
1966 written examination. Radiologists may fulfill the didactic portion of the initial training through
1967 the extensive training in radiation physics, radiation biology and radiation safety they receive
1968 during their residency.
1969
1970 Hands-on training is conducted by a qualified individual who is familiar with the equipment.
1971 Hands-on training means operation of the actual fluoroscope that is to be used clinically (or an
40
-------
DRAFT PROPOSAL
1972 essentially similar fluoroscope), including the use of controls, activation of various modes of
1973 operation, and displays. This phase of training could include demonstrations of the effect of
1974 different modes of operation on the dose rate to a simulated patient and could include
1975 demonstration of the dose-rates at various locations in the vicinity of the fluoroscope.
1976
1977 Clinical operation under a preceptor means operation of the fluoroscope for clinical purposes
1978 under the direct supervision of a preceptor experienced in the operation of the device.
1979 Completion of this phase of training should include written attestation, signed by the preceptor,
1980 that the individual has achieved a level of competency sufficient to function independently as a
1981 fluoroscopy operator.
1982
1983 Training should be conducted initially and then at periodic intervals. Records should be kept of
1984 the training. The records should include the date(s) of training, the name(s) of the person(s)
1985 providing the training, the topics included in the training, the duration of the training, the test
1986 questions, the names of the persons successfully completing the training, and the test scores of
1987 these persons. The training records should also include the signed preceptor statements
1988 described above. Training need not be performed at or by the medical facility, provided that the
1989 facility determines that it meets these requirements and was sufficiently recent, and the facility
1990 obtains written certification of successful completion of the training. Periodic refresher training
1991 should include the didactic training. At the facility's discretion, it may also include hands-on-
1992 operation and clinical operation under a preceptor physician.
1993
1994 Each person who operates or directs the operation of fluoroscopic equipment should be
1995 privileged by the medical facility. Privileging should be contingent upon successful completion
1996 of training as described above. Maintenance of privileges should be contingent upon successful
1997 completion of periodic refresher training and on complying with agency and facility
1998 requirements for the safe use of fluoroscopic equipment. In particular, it is not permissible for a
1999 physician or other medical professional who has not completed this training, and who is not
2000 privileged, to direct the operation of a fluoroscopy unit even if it is operated by a radiologic
2001 technologist.
2002
2003 Operators who perform fluoroscopically-guided procedures with the potential for high patient
2004 doses require additional knowledge and training beyond that necessary for operators whose
2005 practice is limited to low-dose fluoroscopy procedures (ICRP 2000a; Vano 2003). Operator
2006 knowledge includes all the information described in the current American College of Cardiology
2007 Foundation/ American Heart Association/ Heart Rhythm Society/ Society for Cardiac
2008 Angiography and Intervention fluoroscopy clinical competence statement and its successors . In
2009 general, radiologists and interventional cardiologists receive most or all of this information as
2010 part of their training, and are tested on this knowledge as part of the board certification processes
2011 by their respective Boards. Physicians in other medical specialties may or may not have received
2012 training or been examined on this subject matter during their residency or fellowship, and may
2013 require additional training.
2014
2015
2016
41
-------
DRAFT PROPOSAL
2017 Procedures
2018
2019 Fluoroscopic procedures should be performed so that procedure dose is optimized and skin dose
2020 is minimized. This requires the appropriate use of various features of the fluoroscopic
2021 equipment. Further details are available in the published literature (Miller et al. 2010b; NCRP
2022 2010; Sidhu et al. 2009; Stecker et al. 2009; Wagner et al. 2000).
2023
2024 Dose measurement
2025
2026 Methods for estimating PSD can be ranked from most reliable to least reliable. As of 2012, peak
2027 skin dose measuring software is the most reliable, followed by measurement of cumulative air
2028 kerma, KAP, and finally fluoroscopy time combined with a count of the number of fluorography
2029 frames or images. Dosimeters placed on the skin are useful but can provide underestimates for
2030 PSD if placed outside the area of highest skin dose. This area may be quite small (Miller et al.
2031 2003a). PSD and KAP are now the most useful predictors for deterministic and stochastic
2032 injury, respectively. Cumulative air kerma is readily available on fluoroscopy units purchased
2033 after mid-2006 and is an acceptable substitute for PSD. It does not correlate well with PSD in
2034 individual cases (Miller et al. 2003a; Miller et al. 2003b). Fluoroscopy time alone does not
2035 correlate with PSD (Fletcher et al. 2002). Monitoring fluoroscopy time alone also
2036 underestimates the risk of radiation-induced skin effects (O'Dea et al. 1999).
2037
2038 All statements of patient dose contain some degree of uncertainty. As of 2012, dose
2039 measurement accuracy in clinical units has an allowed calibration accuracy of ±35% (FDA
2040 2012d). Even the most sophisticated dose-measurement instrumentation has unavoidable
2041 uncertainties related to variations in instrument response with changes in beam energy, dose rate,
2042 and collimator size. Converting these measurements into skin dose introduces yet further
2043 uncertainties related to beam orientation and inconsistencies in the relationship between the
2044 patient's skin and the interventional reference point. Finally, clinically available dose and KAP
2045 measurements ignore the effect of backscatter from the patient. Backscatter causes the skin dose
2046 to exceed air kerma at the same location by 10 to 40%, depending on the beam area and energy
2047 (ICRU 2005, or most current version). Skin doses estimated from reference dose, KAP, or
2048 fluoroscopy time may differ from actual skin dose by a factor of two or more. Users of dose data
2049 should be aware of these uncertainties. Federal facilities should strongly encourage the purchase
2050 of equipment with features that enhance the accuracy and clinical value of dosimetry systems.
2051
2052 Recordkeeping
2053
2054 A record should be kept of each fluoroscopic procedure. Whenever possible, this should be
2055 performed electronically, with automatic transfer of the necessary data, as appropriate, from the
2056 fluoroscopy unit to a PACS, RIS, and EMR (see above, under Equipment). The record should
2057 list the individual fluoroscopy unit, the date of the procedure, the procedure (e.g., barium enema,
2058 iliac artery angioplasty and stent placement), information identifying the patient, and the name of
2059 the physician operating or directing the operation of the device. The record should also list the
2060 cumulative air kerma from both fluoroscopy and from image acquisition, if available; the kerma -
2061 area product, if available; the cumulative fluoroscopy time and number of images recorded; and
2062 other dose metrics as they are developed. This record should be maintained according to the
42
-------
DRAFT PROPOSAL
2063 Federal facility's requirements.
2064
2065 It is strongly recommended that patient radiation dose data be recorded in the patient's medical
2066 record, including patient skin dose data whenever possible. Where and how these data are
2067 recorded is subject to the policies and procedures of the individual institution. However, the
2068 choice of dose metrics to be recorded should be guided by published recommendations, such as
2069 the guidelines on recording dose in the medical record published by SIR (Miller et al. 2012;
2070 Miller et al. 2004; Stecker et al. 2009).
2071
2072 When the dose to one or more areas of a patient's skin may have exceeded a threshold dose for
2073 deterministic effects, the physician performing the procedure should be advised of this event and
2074 should place an appropriate notation in the patient's medical record (Stecker et al. 2009). The
2075 information should include information on the beam entry sites and the estimated skin dose for
2076 each, if available. Provisions should be made for clinical follow-up of those areas for monitoring
2077 radiation effects. The possibility of overlap of two separate adjacent fluoroscopic fields, where
2078 skin dose of the overlapping area may have exceeded the threshold dose, should be taken into
2079 account. Ideally, skin dose from radiation therapy and imaging modalities other than
2080 fluoroscopy should also be considered. It is recognized that at the time this report was prepared,
2081 no simple method for measuring or estimating skin dose is available. As a substitute, cumulative
2082 air kerma may be used. Threshold values recommended by professional societies or advisory
2083 bodies, such as the ACR, SIR, ICRP and NCRP, should be consulted (ACR 2008c; ICRP 2000a;
2084 Stecker et al. 2009). As of 2012, these threshold values are typically a PSD of 3 Gy or
2085 cumulative air kerma of 3 - 5 Gy (ACR 2008c; NCRP 2010).
2086
2087 Patient management
2088
2089 Management of patients who have received radiation doses high enough to cause deterministic
2090 effects should be guided by recommendations from appropriate advisory bodies, medical
2091 specialty societies, and other organizations, and by current practice (ACR 2008c; Baiter and
2092 Moses 2007; Stecker et al. 2009). For these patients, this includes justifying and documenting
2093 the high radiation dose in their medical record, notifying the patient or their health care proxy
2094 (legally authorized representative) of the radiation dose that has been administered and the likely
2095 consequences, and follow-up by the physician who performed the procedure to determine
2096 whether a skin injury has occurred (Baiter et al. 2010).
2097
2098 Device related deaths, including those related to radiation dose, must be reported by the device
2099 user facility to the device manufacturer and to the Food and Drug Administration in accordance
2100 with 21 CFR 803 (FDA2012b). Device-related serious injuries, including those resulting from
2101 radiation, must be reported by the device user facility to the device manufacturer or, if the
2102 manufacturer is unknown, to the Food and Drug Administration. A serious injury is one that is
2103 life-threatening, results in permanent impairment of a body function or permanent damage to a
2104 body structure, or necessitates medical or surgical intervention to preclude permanent damage or
2105 impairment (FDA 2012a). If a patient's skin receives an absorbed dose that meets the Joint
2106 Commission definition of a reviewable sentinel event from a fluoroscopically guided procedure,
2107 or a dose likely to result in a serious injury, the event also should be reported to the Radiation
2108 Safety Officer and the facility's Patient Safety Manager, or designee (Baiter and Miller 2007;
43
-------
DRAFT PROPOSAL
2109 The Joint Commission 2006).
2110
2111 Quality process
2112
2113 All QA/QI programs for interventional fluoroscopy should include patient radiation safety
2114 aspects. These include evaluation of operator performance in dose optimization and of
2115 procedures where patients received a radiation dose that caused a radiation injury.
2116
2117 A review of radiation doses delivered to patients during fluoroscopically guided interventional
2118 procedures is an essential aspect of any performance improvement program. The dose metrics
2119 for all procedures should be reviewed at intervals (quarterly, for example) for their magnitude
2120 and for the dose distribution of these cases. This will provide a picture of dose utilization; any
2121 abnormally high doses can be reviewed for appropriateness. For example, doses can be
2122 compared to available reference levels. Any recommendations and actions for improvement
2123 should then be implemented.
2124
2125 Analysis of overall dosimetric performance for interventional fluoroscopy procedures,
2126 incorporating the effects of equipment function, procedure protocols, and operator performance,
2127 requires a different process than the reference levels (RLs) used for radiography (NCRP 2010).
2128 It also requires a more detailed presentation of the reference data set. Guidance data for an
2129 interventional fluoroscopy procedure are generated by obtaining data for all instances of that
2130 procedure from a number of different facilities. These data are used to generate Guidance Levels
2131 (GLs), which are similar to the RLs used for radiography. The guidance data set includes the
2132 data for all instances of the procedure at each facility. This differs from the data set used to
2133 generate RLs, which typically includes only a single datum from each facility.
2134
2135 Guidance data sets for interventional fluoroscopy procedures usually demonstrate a lognormal
2136 distribution. The high dose tail is of particular interest, because this tail represents the cases
2137 where doses may be high enough to cause deterministic effects. Because differences between
2138 the shapes of the collected guidance data and the local facility data are potentially useful, the
2139 FGI-procedure guidance data set should characterize the entire distribution, rather than just the
2140 10th and 75th percentile values typically used for radiography RLs. Also, in order to provide a
2141 basis for comparison for facilities that use locally derived substantial radiation dose levels
2142 (NCRP 2010; Stecker et al. 2009), these data sets should indicate the percentage of instances of
2143 each procedure that exceed specific radiation dose levels. Ideally, these percentages should be
2144 presented at 0.5 Gy intervals from 2 Gy to the maximum value observed in the data set.
2145
2146 Guidance data and GLs can be used, to some extent, in a fashion similar to RLs, but the
2147 lognormal shape of dose distributions for interventional fluoroscopy procedures mandates that
2148 the local median (50th percentile) be used for comparison with the guidance data, rather than the
2149 local mean dose. Also, high-dose interventional fluoroscopy cases require further evaluation. It
2150 is possible for the facility's median dose for a procedure to be within an acceptable range (below
2151 the 75th percentile of the guidance data) at the same time that there are an excessive number of
2152 cases with a radiation dose greater than the 95th percentile of the guidance data. It is necessary to
2153 compare the percentage of cases at the facility that exceed the local substantial radiation dose
2154 level (the radiation dose level that triggers radiation follow-up) with the percentage of cases in
44
-------
DRAFT PROPOSAL
2155 the guidance data that exceed the same level. Local percentages that are markedly above or
2156 below the value obtained from the guidance data should be investigated (NCRP 2010).
2157
2158 The following method, using cumulative air kerma as the radiation dose metric, is suggested as
2159 one method of evaluating dose utilization for interventional fluoroscopy procedures (NCRP
2160 2010). It is not the only possible method. Kerma-area product could also be used to evaluate
2161 general dose performance. Kerma-area product can be used to evaluate operator performance
2162 with respect to collimation. However, it does not provide an unambiguous identification of the
2163 cases where a very high skin dose may result in deterministic effects.
2164
2165 An appropriate published guidance data set for the selected procedure (the guidance data) is used
2166 as the starting point, although published guidance data for FGI procedures are sparse as of 2012
2167 (Baiter et al. 2008; Bleeser et al. 2008; Brambilla et al. 2004; IAEA 2009; Miller et al. 2009;
2168 Vano et al. 2008a; Vano et al. 2009).
2169
2170 A facility should judge its dose performance for interventional fluoroscopy procedures in several
2171 steps. The first step is to compare the local substantial dose radiation level to the guidance data.
2172 The facility's local substantial radiation dose level is either a value taken from the literature
2173 (ACR 2008c; Mahesh 2008; Stecker et al. 2009) or a locally determined value. The percentage
2174 of procedures in the guidance data set that exceed this value can now be determined.
2175
2176 The next step is to characterize the dose distribution for all instances of a specific procedure
2177 performed at the facility. Evaluation of subsets of these data sorted by procedure room and
2178 operator can be useful as well, as discussed below. The percentage of instances exceeding the
2179 local substantial radiation dose level, and the median value of the entire local data set (and
2180 appropriate subsets) is calculated.
2181
2182 The local median can be compared with the 10th, 50th (median) and 75th percentiles of the
2183 guidance data. A median value below the 10th percentile of the guidance data may indicate
2184 incomplete procedures. A median value between the 50th and 75th percentile of the guidance data
2185 could be due to clinical differences between the guidance data population and the local facility
2186 population or other factors. Understanding the relevant reasons may be useful. An investigation
2187 is warranted if the local median exceeds the 75th percentile of the guidance data (IAEA 2009;
2188 NCRP 2010). This step is analogous to the analysis performed using RLs for radiographic
2189 examinations.
2190
2191 The percentage of instances exceeding the local substantial radiation dose level can be compared
2192 to the percentage of instances exceeding the substantial radiation dose level in the guidance data.
2193 Local percentages significantly above or below the value obtained from the guidance data should
2194 be investigated.
2195
2196 It can be useful to perform the same analysis using a reference dose value of 3 Gy as well as the
2197 local substantial radiation dose level. An interventional fluoroscopy procedure is in the
2198 potentially-high radiation dose category if more than 5% of instances of that procedure exceed a
2199 reference dose of 3 Gy (NCRP 2010). If fewer than 5% of the instances of the procedure at the
2200 local facility exceed this value, then the procedure, as performed at the local facility, is not in
45
-------
DRAFT PROPOSAL
2201 that category. At that local facility, the procedure may be performed safely in a fluoroscopy
2202 suite that does not meet the requirements of IEC 60601-2-43 (IEC 2010). Also, those procedures
2203 at the local facility that are not in the potentially-high radiation dose category may be audited
2204 less frequently than those that are in that category.
2205
2206 Lastly, the overall distribution of the local data may be compared to the distribution of the
2207 guidance data. Displacement or distortion of the local distribution histogram relative to the
2208 guidance data may be due to differences in equipment, clinical complexity, or other factors.
2209
2210 The analysis may be extended to individual operators or interventional fluoroscopy procedure
2211 rooms by comparing operator- or room-specific data to either a facility's local distributions or to
2212 pooled distributions of data for multiple facilities (e.g., (Miller et al. 2009)). Care should be
2213 taken in such an analysis to account for statistical interactions (e.g., statistical confounding
2214 between the operator and the interventional fluoroscopy procedure room).
2215
2216 Procedures resulting in a substantial patient radiation dose should be reviewed on a regular basis.
2217 Reported potential radiation injuries should be reviewed at the regular QA meeting, with any
2218 available diagnoses, planned patient follow-up, and outcomes. If a radiation injury occurred, the
2219 procedure should be reviewed for appropriate use of radiation in the clinical context. It may be
2220 appropriate to periodically re-report on the status of known radiation injuries. Additionally,
2221 reporting of these cases to the institution's Radiation Safety Officer is desirable.
2222
2223 Staff safety
2224
2225 Other than the patient who is being examined, only staff and ancillary personnel required for the
2226 procedure, or those in training, should be in the room during the fluoroscopic examination. No
2227 body part of any staffer ancillary personnel involved in a fluoroscopic examination should be in
2228 the primary beam (Miller et al. 2010b). If primary beam exposure is unavoidable, it should be
2229 minimized. As required by various states, all personnel in the room during fluoroscopic
2230 procedures should be protected from scatter radiation by either protective aprons or whole-body
2231 shields of not less than 0.25 mm of lead-equivalent material. An apron with lead equivalence of
2232 at least 0.35 mm is recommended. Thyroid and eyes should be protected if the potential
2233 exposure to the worker will exceed 25% of the annual regulatory dose limits for those organs. It
2234 is strongly recommended that protective aprons and gloves be evaluated at least annually for lead
2235 protection integrity (Miller et al. 2010b; NCRP 2010).
2236
2237 Pregnant individuals involved in fluoroscopically guided procedures generally do not need to
2238 limit their time in the procedure room to remain below the dose limit for the embryo and fetus, as
2239 long as they use appropriate protective garments and radiation protection methods, and their
2240 occupational exposure is adequately monitored (NCRP 2010).
2241
2242
2243
46
-------
DRAFT PROPOSAL
2244 COMPUTED TOMOGRAPHY
2245
2246 Computed tomography (CT) is an imaging modality that utilizes one or more x-ray beams to
2247 acquire projection images from many angles around the patient. The projection images are
2248 mathematically manipulated to obtain tomographic images that depict x-ray attenuation in a two
2249 dimensional cross sectional, project! onal or three dimensional representation of the subject's
2250 anatomy.
2251
2252 There have been important technological advances that have greatly increased the clinical
2253 usefulness of CT imaging. However, these improvements have also led to increased use of CT,
2254 imaging of larger volumes of the body, and acquiring an increased number of image sequences
2255 either during the various phases of tissue enhancement following contrast injection or to
2256 dynamically evaluate areas affected by motion. These are incredibly powerful diagnostic tools
2257 that are invaluable to patient management and allow the elimination of more dangerous invasive
2258 procedures, such as exploratory surgery. But with this great benefit has come a price: there has
2259 been an increase in radiation dose to the population, as well as to the individual patient.
2260
2261 In the U. S., the number of CT procedures performed annually increased by 10% to 11 % per year
2262 from 1993 to 2006 (NCRP 2009). Although CT procedures comprise only about 17 % of all
2263 medical x-ray imaging procedures, they now impart about 49 % of the cumulative effective dose
2264 from medical procedures received by the population of the U.S. (Mettler et al. 2008). As of
2265 2012, a typical single CT imaging procedure of the chest, abdomen, or pelvis of an adult imparts
2266 an effective dose on the order of 3-7 mSv (McCollough 2008; Mettler et al. 2008). These values
2267 are for single phase exams and the effective doses for multiple phase exams are correspondingly
2268 larger. Thus, CT imparts some of the largest doses per procedure in diagnostic medical imaging.
2269 These doses are significantly exceeded only by the doses from some complex fluoroscopically-
2270 guided interventional procedures.
2271
2272 Except in the extreme circumstance of multiple irradiations of the same anatomic region, the
2273 doses from CT examinations are unlikely to cause deterministic effects such as erythema or
2274 epilation (hair loss). Instead, the main concern is stochastic effects, particularly cancer. The risk
2275 to the patient is determined mainly by the doses to organs in or near the scanned portion of the
2276 patient, the age and gender of the patient, and the likely remaining lifespan of the patient.
2277
2278 In 2001, it was reported that standard adult technique factors were commonly used for CT
2279 imaging of patients in the U.S. regardless of body habitus, including children and even infants
2280 (Brenner etal. 2001; Paterson et al. 2001). If adult technique factors are used for imaging the
2281 abdomen or thorax of a small child or infant, the larger doses together with the larger risk of
2282 cancer per unit dose is estimated to pose a risk of fatal cancer on the order of one per thousand
2283 examinations (Brenner et al. 2001). Therefore, it is essential to optimize dose when imaging
2284 children (FDA 2001). Of the many methods for adjusting CT techniques for children, perhaps
2285 the simplest and most widely used techniques utilizes the Breslow method familiar to clinical
2286 providers as a way to estimate the weight, drug dosing, and equipment sizing for children. Many
2287 sites have developed specific CT protocols that adjust the kVp and mAs based on the
2288 approximate size of a child matching each Breslow color scheme category. Professional
47
-------
DRAFT PROPOSAL
2289 societies provide excellent guidance on imaging, such as the "Image Gently" campaign (Goske
2290 MJ et al. 2008; Strauss et al. 2010).
2291
2292 Many advances in CT technique and technology have been specifically targeted at reduction of
2293 the radiation dose delivered to the patient during CT examinations. To be effective, these
2294 techniques must be used, and used properly. It is imperative that Radiological Medical
2295 Practitioners, physicists, and technologists involved in CT imaging keep abreast of current
2296 developments and utilize all techniques available to them to reduce the patient's radiation
2297 exposure as much as possible while obtaining the clinically needed information.
2298
2299 Equipment
2300
2301 CT was introduced in the mid-1970s. For several decades, a constant x-ray tube current was the
2302 only available technology for performing a CT examination. Tube current did not change,
2303 regardless of the angle of the x-ray beam as the x-ray tube rotated around the patient, and
2304 regardless of the attenuation along the path of the beam through the patient. However, this
2305 attenuation varies greatly with the angle of the beam and the location on the patient's body. As
2306 of 2012, developments in technology allow automated tube current modulation, providing
2307 similar image quality with lower radiation dose. Facilities should use equipment that provides
2308 relevant patient dose information. This equipment should allow the facility to program in dose
2309 alerts to inform operators if selected operating parameters might produce a radiation dose
2310 exceeding that recommended by the facility. Equipment manufacturers should incorporate these
2311 features into the equipment.
2312
2313 The dose of radiation to a patient, in conjunction with the attenuation provided by the part of the
2314 patient that is scanned and the presence or absence of IV contrast, determines the signal-to-noise
2315 ratio in the resultant images. The signal-to-noise ratio needed for diagnostic confidence depends
2316 upon the diagnostic task. Smaller and thinner patients require smaller doses than larger and
2317 thicker patients to produce similar signal to noise ratios in the images. Imaging procedures to
2318 detect or assess larger structures and structures with more inherent or enhanced contrast
2319 (difference in density) require a smaller dose than imaging procedures to detect or assess smaller
2320 structures and those with less inherent contrast.
2321
2322 Stand-alone CT scanners have been complemented by the development of hybrid modalities such
2323 as Positron Emission Tomography/CT [PET/CT] and Single Photon Emission Computed
2324 Tomography/CT [SPECT/CT]. These hybrid modalities use two equipment components to
2325 acquire two types of images of a patient in the same setting, without changing the patient's
2326 position on the imaging system table. This allows co-registration of image data so that the
2327 anatomic detail provided by one imaging modality can be matched to the physiologic marker
2328 capability of the second modality to provide more specific information about the location and
2329 extent of disease. These CT devices may be operated at lower doses if the CT portions of the
2330 exams are not intended to be used for diagnosis independent of the SPECT or PET exam.
2331
2332 Technological development in image reconstruction, increases in computer processor power,
2333 equipment innovation, and optimization techniques in general have led to a marked increase in
2334 the ability to obtain adequate quality images at lower patient doses. These improvements should
48
-------
DRAFT PROPOSAL
2335 be implemented to the fullest extent practicable. Facilities should use equipment that provides
2336 relevant patient dose information. This equipment should allow the facility to program in dose
2337 alerts to inform operators if selected operating parameters might produce a radiation dose
2338 exceeding that recommended by the facility. Equipment manufacturers should incorporate these
2339 features into the equipment.
2340
2341 Testing and Quality Assurance
2342
2343 Equipment testing for quality assurance should be performed after installation but before first
2344 clinical use, annually thereafter, and after each repair or modification that may affect patient dose
2345 or image quality. Testing should be performed as specified in the section of this document
2346 entitled Technical Quality Assurance in Medical Imaging with X-Rays. In addition, the
2347 recommendations found in the current version of ICRP Publication 102 (NCRP 1989b) should be
2348 followed when applicable.
2349
2350 A quality control program should be established. The program should conform to the ACR
2351 Technical Standard for the Diagnostic Medical Physics Performance Monitoring of Computed
2352 Tomography (CT) Equipment or equivalent guidance.
2353
2354 Personnel
2355
2356 A CT system should only be operated by a Radiologic Technologist registered by the American
2357 Registry of Radiological Technologists (ARRT) or equivalent, preferably with advanced
2358 certification in CT, operating under the supervision of a Radiological Medical Practitioner with
2359 appropriate training in CT physics, radiation safety and CT image interpretation.
2360
2361 Ideally, a PET/CT or SPECT/CT should be operated by a technologist certified in both nuclear
2362 medicine and CT. However, a PET/CT or SPECT/CT may also be operated by a nuclear
2363 medicine technologist with Certified Nuclear Medicine Technologist (CNMT) or Radiological
2364 Technologist Nuclear qualified (RT(N)) certification and additional training in CT imaging
2365 sufficient to safely operate a CT system. Alternatively, a PET/CT may be operated by a
2366 technologist who is qualified to operate a CT system and who also has additional training in PET
2367 imaging sufficient to safely operate a PET system. If a technologist who meets these
2368 requirements is not available, the PET/CT or SPECT/CT system should be operated by two
2369 technologists, one a nuclear medicine technologist qualified to operate the PET or SPECT
2370 system and the other a Diagnostic Radiological Technologist (DRT) or a therapist in radiation
2371 oncology who is qualified to operate the CT system. Utilization and training requirements for
2372 the operation of other hybrid modalities should be evaluated as new combinations of modalities
2373 emerge.
2374
2375 Procedures
2376
2377 One of the most effective ways to optimize the dose of radiation delivered to the patient in a CT
2378 study is to tailor the study to the patient's specific needs.
2379
49
-------
DRAFT PROPOSAL
2380 A CT protocol specifies the parameters for the image acquisition and largely determines the dose
2381 to the patient. It defines the portion of the patient's anatomy to be imaged, whether and how
2382 contrast agents will be administered, the number and timing of imaging sequences, and
2383 acquisition technical parameters. Imaging sequences in a multiphase study may include several
2384 phases, such as a pre-contrast phase, an arterial phase, a venous phase and/or a delayed phase.
2385 Acquisition technical parameters may include pitch, collimation (beam width), kV, mA (constant
2386 or modulated), rotation time, physiologic gating, image quality factors, and reconstruction
2387 method. In addition:
2388 1. In some cases, the kV may be adjusted for the type of examination (e.g., contrast enhanced
2389 angiography) to accommodate patient size.
2390 2. If constant mA is selected, the protocol should utilize a chart for adjusting the mA for the
2391 patient's size (girth or thickness). If mA modulation is selected, the protocol should specify
2392 the parameters determining the balance between image noise and patient dose.
2393 3. Organ-specific tube current modulation, where available, technically feasible, and clinically
2394 appropriate, should be considered to protect organs such as the breast in younger female
2395 patients and the lens of the eye.
2396 4. Where applicable, the prescription of image acquisition technique factors should take into
2397 account the availability of advanced image reconstruction techniques to decrease the
2398 required patient dose.
2399 5. Once the image sequence is acquired, the user can select alternative reconstruction
2400 parameters (e.g., reconstructed slice thickness) to view the images differently without
2401 having to rescan the patient.
2402
2403 Each CT protocol should be documented in two ways. The first way is a document detailing all
2404 relevant information. The second way provides a more limited subset of programmable
2405 information, primarily acquisition parameters, stored on the imaging device.
2406
2407 It is important to image only the area of anatomy in question and acquire only the necessary
2408 sequences. This is accomplished by determining the imaging protocol for the examination.
2409 Where appropriate, the radiological medical practitioner should select and adjust the protocol to
2410 ensure that the patient is examined using the appropriate techniques and dose.
2411
2412 The technologist performing the study is responsible for limiting the length of the patient being
2413 scanned to the minimum clinically necessary. The technologist is also responsible for setting up
2414 the CT system so that the correct protocol is used and the imaging parameters are appropriate for
2415 the patient's size, age, and intended examination. Before performing the study, the technologist
2416 should confirm that the technical parameters and the radiation dose metric are appropriate for the
2417 patient and planned study. If existing equipment does not provide a dose metric, efforts should
2418 be made to upgrade or replace it. To prevent accidental overexposure, the projected dose should
2419 correspond to the doses normally associated with the protocol, within reasonable variability.
2420 This should be confirmed again after the patient has been scanned.
2421
2422 Optimization of CT protocols is important for minimizing patient dose. The facility's standard
2423 protocols for CT imaging should be reviewed by a team, including a physician expert in CT
2424 image interpretation, a technologist expert in performing CT examinations, and a qualified
2425 physicist:
50
-------
DRAFT PROPOSAL
2426 1. when the protocol is developed,
2427 2. when the protocol is significantly modified,
2428 3. on a regular basis (preferably annually), and
2429 4. after an equipment upgrade or replacement.
2430
2431 It is strongly recommended that procedures be established to avoid inadvertent or unapproved
2432 modification of CT protocols. Methods, such as limiting access through the use of passwords,
2433 should be adopted to implement these procedures. Superseded protocols should be archived for
2434 future reference.
2435
2436 Reviews and revisions should align protocols with current clinical practice, evaluate the
2437 magnitude of delivered radiation doses, and optimize the radiation dose. Modifications of the
2438 protocol to suit the needs of an individual patient generally do not require a specific review, but
2439 the impact on radiation dose should be understood and considered.
2440
2441 Operator selectable parameters on CT scanners that affect the dose to the patient include the
2442 voltage applied to the x-ray tube (kV), the x-ray tube current (mA) or current-time product per
2443 x-ray tube rotation (mAs), and the pitch (incremental table movement per x-ray tube rotation
2444 divided by the nominal x-ray beam width at isocenter). The radiation dose to the patient within
2445 the scanned volume is approximately proportional to the square of the kV and is proportional to
2446 the effective mAs (the mAs divided by the pitch). Technique factors should be appropriate for
2447 the size (and not just the age) of the patient and the body part being imaged. In particular, adult
2448 technique factors should not be used for children and infants. Technique factors should be
2449 chosen that produce a diagnostically adequate image rather than a "perfect image," thus
2450 matching the radiation exposure to the diagnostic requirement. If available on the CT scanner,
2451 automated modulation of the tube current should be used for those procedures for which it
2452 produces substantial dose savings, e.g., scans of the thorax. Using this feature appropriately can
2453 reduce dose significantly, whereas errors in its use have produced substantial increases in dose.
2454 For gated cardiac CT imaging, utilize (when available) the feature that reduces or terminates the
2455 beam current during portions of the cardiac cycle that will not be used for image reconstruction
2456 (ICRP2012).
2457
2458 Several phantom-derived dose indices specific to CT have been defined. These can be useful to
2459 compare one study protocol to another in the assessment of benefit and risk; these are described
2460 in the literature (McNitt-Gray 2002). Two indices in common use are the volumetric computed
2461 tomography dose index (CTDIyoL), which is approximately the average dose in the scanned
2462 volume, and the dose-length product (DLP), defined as the CTDIvoL multiplied by the scanned
2463 length. These indices indicate the radiation exposure delivered by the CT scanner to a phantom,
2464 not the specific radiation energy (i.e., dose) received by any patient. Both of these measures may
2465 be available from current CT scanners, and future devices may incorporate more accurate and
2466 useful dose metrics. The DLP and the portion of the patient that is scanned (e.g., head, thorax, or
2467 abdomen) may be used to estimate the effective dose to the patient. Effective dose is an
2468 indicator of stochastic risk. CT dose indices should be recorded as part of the patient record in
2469 the imaging study or medical record.
2470
51
-------
DRAFT PROPOSAL
2471 BONE DENSITOMETRY
2472
2473 Bone densitometry noninvasively measures certain physical characteristics of bone that reflect
2474 bone strength, typically reported as bone mineral content or bone mineral density. It is used for
2475 diagnosing osteoporosis and estimating fracture risk. It is also used to monitor changes in bone
2476 mineral content, whether from age, conditions causing bone mineral loss, or treatment. Devices
2477 that measure bone mineral content are called bone densitometers. Non-invasive methods for
2478 measuring bone mineral content are based on the transmission of x-rays or gamma rays through
2479 the bone. The radiation beams can be produced as pencil or fan beams. The advantage of the
2480 latter is that it is faster, but the radiation dose is increased by a factor of about 4.
2481
2482 There are also devices that use the transmission of sound waves through bone to assess bone
2483 structure. These are ultrasound devices that do not directly measure bone mineral content, but
2484 are also commonly called densitometers.
2485
2486 Equipment
2487
2488 The principal methods in routine clinical use in 2012 for the non-invasive measurement of bone
2489 mineral content using ionizing radiation include: x-ray absorptiometry and quantitative x-ray
2490 computed tomography (QCT). X-ray absorptiometers measure attenuation of two x-ray beams
2491 of well-separated average photon energies to discriminate between bone mineral and soft tissue.
2492 This method is called dual-energy x-ray absorptiometry (DXA or DEXA). The other principal
2493 method for assessment of bone structure regarding osteoporosis is quantitative ultrasound (QUS)
2494 (ACR 2008a; Bonnick and L. 2006).
2495
2496 Of all the methodologies available in 2012, DXA is the only one that can be used to make a
2497 diagnosis of osteoporosis. The World Health Organization has developed criteria for diagnosing
2498 normal bone density, osteopenia, and osteoporosis (Kanis et al. 1994). This classification is
2499 specific for DXA (total hip or femur and neck, PA lumbar vertebrae, or distal 1/3 radius) and
2500 cannot be applied to any other technology (ISCD 2007a; ISCD 2007b). As of 2012, DXA is also
2501 the most commonly used technology for monitoring changes in bone mineral density (BMD).
2502 QCT is sometimes used to monitor changes in the trabecular portion of the vertebrae when there
2503 is a need to measure changes more frequently than with DXA. QCT, nevertheless, involves a
2504 much higher exposure to radiation, especially if done sequentially, and is more expensive and
2505 requires more specialized equipment and staff expertise than DXA.
2506
2507 Bone mineral can be assessed non-invasively by these methods at several sites in the axial and
2508 appendicular skeleton. DXA is most commonly used to assess the lumbar spine, proximal
2509 femurs, and distal radii. DXA measurements of the thoracic spine cannot be performed because
2510 the ribs overlap the thoracic vertebrae. Measurements of the proximal femurs are commonly
2511 referred to as "hip" measurements, but the bone mineral content measurements themselves are
2512 limited to the proximal femurs. DXA and SXA devices are available for measurements of
2513 peripheral sites such as the radius and the calcaneus. The standard evaluation of bone mineral
2514 density includes evaluation of at least one proximal femur and the lumbar spine in the frontal
2515 plane.
2516
52
-------
DRAFT PROPOSAL
2517 Some DXA devices are also capable of imaging the spine to detect vertebral fractures. This is
2518 called vertebral fracture assessment (VFA). Detection of vertebral compression fractures is an
2519 independent method for diagnosing osteoporosis. This is performed with imaging of the thoracic
2520 and lumbar spine in the lateral plane. Exposure to radiation is higher with VFA than with DXA
2521 but still considerably lower than for conventional radiography of the same area (Genant et al.
2522 1996).
2523
2524 Some DXA devices allow the C-arm holding the x-ray tube and detector to rotate to a position
2525 permitting lateral bone mineral density measurements of the lumbar spine in the supine patient,
2526 in addition to the usual PA or AP measurements. Some DXA devices permit the acquisition of
2527 projection images of the entire lateral spine for vertebral morphometry. Furthermore, some
2528 DXA devices permit PA or AP scans of the entire body for body composition analysis, providing
2529 an estimation of total bone mineral mass, lean body mass, and fat mass.
2530
2531 QCT measurements are usually performed of the lumbar spine, but there are options to perform
2532 measurements at other anatomical sites as well. Unlike DXA, QCT is able to differentiate
2533 mineral content in the bone as opposed to mineral content outside bones, such as in osteophytes
2534 or aortic calcifications. The presence of these extra-osseous calcifications makes the use of
2535 DXA of the vertebrae less reliable in older people. QCT, on the other hand, is able to focus on
2536 the trabecular or cortical component of bone. QCT may be performed with a standard CT
2537 system; however, a special phantom and software are needed. QUS is used to measure sites in
2538 the append!cular skeleton, most commonly the calcaneus.
2539
2540 Testing and Quality Assurance
2541
2542 Each facility performing bone densitometry should have a quality assurance program. The
2543 procedures for this program should be documented in writing. The program should conform to
2544 manufacturer's recommendations and recommendations of professional societies such as the
2545 International Society for Clinical Densitometry (ISCD) and the American College of Radiology.
2546
2547 The quality assurance program should include daily assessments of accuracy and periodic
2548 assessments of precision. Cross calibration should be performed whenever the densitometer is
2549 repaired, modified, or replaced. This helps ensure proper measurement of bone mineral content,
2550 detection of osteoporosis, estimation of fracture risk, and changes over short and long periods of
2551 time (i.e., minutes and years) even as equipment is repaired, modified, or replaced.
2552
2553 Accuracy check
2554
2555 Accuracy is the degree to which a measurement value estimates the actual value of the quantity
2556 being measured. The test for accuracy primarily measures equipment characteristics. Most
2557 densitometers will not allow a DXA scan to be performed unless the accuracy test is passed.
2558 Phantoms are available and an accuracy assessment should be obtained daily.
2559
2560
2561
2562
53
-------
DRAFT PROPOSAL
2563 Precision
2564
2565 Precision is the degree to which the same value is obtained when a measurement is repeated
2566 (Bonnick and L. 2006; ISCD 2012). The better the precision, the smaller the Least Significant
2567 Change (LSC), and the more likely is the detection of small changes in BMD. Precision studies
2568 assess the technologist's skills at positioning the patient reproducibly. Several patient factors
2569 affect positioning, including obesity, arthropathies, pain, deformities, fractures, and other
2570 conditions limiting patient mobility. Phantoms are not available for assessing precision; this is
2571 due to the complexity of relating phantom data to patient results. Given these clinical variables
2572 and lack of appropriate phantom, precision studies should be conducted on subjects who are
2573 representative of the bulk of the population scanned at the particular facility. For instance, if
2574 most patients scanned in a facility are over the age of 65 years, precision studies should not be
2575 done in that facility on young athletes. Each facility should establish a range of acceptable
2576 precision performance and ensure that each technologist meets this standard. If a facility has
2577 more than one technologist, an average precision error combining data from all technologists
2578 should be used to establish precision error and LSC for the facility.
2579
2580 For DXA, precision is affected by the positioning of patients. Therefore, precision assessments
2581 should be performed using repeated measurements of patients, with repositioning of the patients
2582 between measurements. Precision studies can be done on either 30 patients scanned twice (after
2583 the patient is repositioned in between scans) or 15 patients scanned 3 times, also after
2584 repositioning in between each scan (ISCD 2012). The technician's or facility's precision is then
2585 used to calculate the Least Significant Change (LSC) to determine whether an observed change
2586 in BMD over a period of time is significant (higher than LSC) or not (less than the LSC). The
2587 patients imaged for precision studies should be representative of the facility's patient population.
2588 Retraining should occur if a technologist's precision is worse than values recommended by
2589 professional societies, e.g., ACR and ISCD.
2590
2591 Cross calibration
2592
2593 Cross-calibration is a method to derive equivalent BMD values when measured on the original
2594 densitometer and a modified or new densitometer. Cross-calibration should be performed when
2595 repairing, modifying, or replacing the entire system or any portion of the system that might alter
2596 the absolute BMD value. The old and new densitometers should be cross-calibrated to establish
2597 a new baseline. As with precision assessments, phantoms are not available for cross calibration.
2598 Cross-calibration is conducted in-vivo by scanning 60 to 100 patients with a wide range of bone
2599 densities (normal to osteoporosis) on both the old and new densitometer. A cross-calibration
2600 equation is then developed (by using linear regression methods), and can be used to predict the
2601 BMD value on the different densitometer.
2602
2603 Justification for quality assurance studies
2604
2605 Patients enrolled in precision studies benefit indirectly and may benefit directly because these
2606 studies improve the reliability of the results. Patients enrolled in cross calibration studies benefit
2607 directly in that these processes allow a better comparison with future scans done on the same or
2608 different equipment. It is in a patient's best interest to be scanned in a facility where precision is
54
-------
DRAFT PROPOSAL
2609 high and LSC small, as the results are more reliable and comparisons with other scans more
2610 meaningful.
2611
2612 Precision and cross-calibration studies conducted by scanning patients are not research. Thus,
2613 these studies do not need approval of an institutional review board. However, the facility should
2614 obtain informed consent from each patient participating in a precision or cross-calibration study.
2615 Although each scan results in a low effective dose to the individual patient, radiation doses to the
2616 individual patient can be reduced by scanning a larger number of patients a fewer number of
2617 times and by not including a patient in both precision and cross-calibration studies. Patients or
2618 staff should not be scanned solely for the purpose of training.
2619
2620 Cross-calibration should be performed when changing the entire system or any portion of the
2621 system that might alter the absolute BMD value.
2622
2623 Patient radiation dose should be determined by a qualified physicist or a qualified medical health
2624 physicist after installation, after service that may affect the radiation dose, and at least annually
2625 thereafter.
2626
2627 In most cases, structural shielding will not be required for DXA or SXA devices or for QCT
2628 devices designed for use only on the append!cular skeleton. Nonetheless, the radiation safety
2629 officer or a qualified physicist should make a determination whether shielding is needed. After
2630 device installation, whether or not additional shielding is installed, dose measurements should be
2631 made in adjacent areas and at the operator's station (which may be inside the room) and should
2632 be documented in a written report. This will help determine the need for occupational dosimetry
2633 and provide a historical record to ensure proper equipment functioning.
2634
2635 Personnel
2636
2637 Technologists performing absorptiometry should have documented formal training in the use of
263 8 the absorptiometry equipment they are operating, including performance of all manufacturer -
2639 specified and facility quality assurance (QA) procedures. Each person performing bone
2640 densitometry should meet the State licensing requirements in addition to at least one of the
2641 following qualifications:
2642 1. be a Diagnostic Radiologic Technologist (DRT),
2643 2. be certified by the American Registry of Radiologic Technologists (ARRT) in Nuclear
2644 Medicine Technology,
2645 3. be certified by the Nuclear Medicine Technology Certification Board,
2646 4. be certified by the International Society of Clinical Densitometry as a Certified
2647 Densitometry Technologist,
2648 5. have ARRT post-primary certification in Bone Densitometry, or
2649 6. have state licensure or limited licensure in Bone Mineral Densitometry, when the licensure
2650 requires successful completion of the ARRT Limited Scope Bone Densitometry
2651 Exami nati on.
2652
55
-------
DRAFT PROPOSAL
2653 Interpretation of the results is important and the interpreting Radiological Medical Practitioner
2654 should be knowledgable in bone densitometry. Reliance on the report generated by the
2655 equipment alone is inadequate. Clinicians should also examine the plates and raw data.
2656
2657 Procedures
2658
2659 Organizations that use bone densitometry should refer to current versions of procedures or
2660 position statements issued by professional organizations (ISCD 2007a; ISCD 2007b). The
2661 following guidance applies to DXA scans.
2662
2663 Before the DXA scan, the technologist should:
2664 1. Ensure that the various quality assurance parameters have been fulfilled.
2665 2. Verify that there are no contraindications to the DXA scans. Pregnant patients or patients
2666 likely to be pregnant should not have a DXA scan. It is also not recommended to scan
2667 patients whose weight exceeds the weight limit of the densitometer as the results may not
2668 be accurate and the densitometer table may be damaged.
2669 3. Verify that there are no artifacts. Patients who have a prosthetic hip or orthopedic device in
2670 the lumbar vertebrae should not have this part of the body scanned. It is also recommended
2671 not to scan patients who have taken calcium supplements the day of the scan as the calcium
2672 tablet may be in the path of the X-rays and artificially elevate the mineral content of the
2673 area scanned. Similarly patients who have undergone radiological contrast studies on the
2674 abdomen should not be scanned until the contrast material is no longer in the patient's
2675 body. Patients should not have metallic objects on the parts scanned, including navel rings
2676 which interfere with the absorption of radiation. Other common artifacts include zippers,
2677 buttons and wallets.
2678 4. Enter and verify the accuracy of all the relevant patient demographic information, such as
2679 the age, race, gender, weight and height. Any erroneous information will invalidate the
2680 subsequent calculation of the T- and Z-scores and hence the validity of the scan.
2681 5. Position the patient according to the criteria set by the manufacturer. If it is not possible to
2682 position the patient as per the recommendations because the patient is unable to be placed
2683 in that position because of pain or limitation of movement, the technologist should make a
2684 note to that effect.
2685 6. Note the scan mode (e.g., fan beam or pencil beam) and the type of leg block used.
2686
2687 During the DXA scan:
2688 1. The patient must refrain from moving.
2689 2. The technologist should:
2690 a. Ascertain that the patient's positioning is good. If the patient positioning is not as per
2691 the accepted recommendations, the subsequent analysis of the scan will not be valid.
2692 b. Ascertain that there are no artifacts.
2693 c. Ascertain that all the regions of interest are clearly visualized.
2694 d. Stop the DXA scan and restart it if positioning is not adequate, if there are artifacts, or if
2695 the regions of interest are not clearly visualized.
2696
2697 Analysis of the DXA scan:
2698 1. Before the analysis, the technologist needs to ascertain that:
56
-------
DRAFT PROPOSAL
2699 a. The patient's demographics are correctly noted.
2700 b. The patient's positioning is good.
2701 c. There are no artifacts.
2702 d. The various regions of interest are clearly visualized.
2703 2. During the analysis, the technologist will follow the manufacturer's recommended
2704 procedure to identify the various regions of interest.
2705
2706 After the analysis the technologist will print out the results of the exam that would have been
2707 configured according to parameters set by the facility where the scans are done.
2708
2709 Reporting the DXA scan results:
2710 1. Reports are automatically generated by the equipment, and should be modified to meet the
2711 needs of the facility where the scans are done. Other information also may be added such
2712 as risk factors for osteoporosis and fracture risk assessment FRAX scores for hips and other
2713 major fracture sites. FRAX is the World Health Organization's (WHO's) Fracture
2714 Assessment Tool, a computer program used to estimate the probability of the patient
2715 sustaining a hip or other major osteoporotic fracture in the following ten years (WHO 2004;
2716 WHO 2012). Various models of reporting are also available from the International Society
2717 of Clinical Densitometry. These may include information about recommended diagnostic
2718 tests and treatment options. It is important however, to tailor the reports to the needs of the
2719 referring physicians.
2720 2. Various report styles exist. The ones preferred by the facility and which satisfy the needs
2721 of the referring physician should be used. Structured reports should be used if electronic
2722 records are maintained by the facility.
2723
57
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DRAFT PROPOSAL
2724 DENTAL
2725
2726 Diagnostic imaging is an integral part of dentistry. Dental radiographs are estimated to
2727 contribute approximately one percent (0.006 mSv) of the total population's effective dose. The
2728 daily background effective dose to a member of the U.S. general population is estimated to be
2729 3.0 mSv/365 = 0.008 mSv/day (NCRP 2009). As of 2012, there is no scientific or epidemiologic
2730 evidence to suggest that the effective dose to the U.S. population from dental diagnostic
2731 radiographic procedures estimated to be in the range of 0.006 mSv carries significant potential
2732 biological risk either at the population level, or individual level.
2733
2734 The dental health-care worker's goal is to keep radiation exposures to the minimum necessary to
273 5 meet diagnostic requirements. In 2003, the NCRP updated its recommendations on radiation
2736 protection in dentistry (NCRP 2003). The Centers for Disease Control and Prevention published
2737 its Guidelines for Infection Control in Dental Health-Care Settings in 2003, and the U.S. Food
2738 and Drug Administration along with the American Dental Association updated selection criteria
2739 for dental radiographs in 2004 (ADA FDA 2004; CDC 2003). In 2006, the American Dental
2740 Association published its practice recommendation for the use of dental radiographs . All of
2741 these recommendations were considered when developing the following guidelines.
2742
2743 Equipment
2744
2745 It is strongly recommended that dental x-ray machine be capable of being operated in at least the
2746 60-90 kVp range, with the x-ray beam filtration consistent with the FDA requirements ((FDA
2747 2012f) Table 1). It is also strongly recommended that the equipment be collimated with a lead-
2748 lined 40 cm (16 in) beam indicating device (BID) (NCRP 2003), which results in less beam
2749 divergence and less volume of patient's tissue irradiated per exposure. Utilization of rectangular
2750 collimation is recommended for intra-oral techniques. This further restricts the beam to
2751 approximately the size of the film/imaging receptor being used (Gibbs 2000; NCRP 2003). Use
2752 of rectangular collimation reduces the exposed area to approximately 48% compared with round
2753 collimation. This improves image quality by reducing scatter, resulting in a radiograph with
2754 better resolution and better contrast.
2755
2756 The dental health professional (dentist or dental hygienist) has a variety of image receptors to
2757 select from that include conventional film, along with evolving digital technology which include
2758 photostimulable imaging plates and digital imaging sensors. Although digital radiography offers
2759 a potential for significant dose reduction, the number of retakes (commonly due to poor
2760 positioning of the bulky sensors with encumbering wire) may result in actual increased dose for
2761 the patient unless care is given to providing proper training and the use of image receptor
2762 positioning devices. Furthermore, due to the smaller active area of some sensors, more than one
2763 exposure may be required to cover the anatomical area imaged using a single conventional film.
2764 Therefore, it is recommended that an image receptor positioning device be used with sensors,
2765 that specific and ongoing training be given to orient operators on ways to eliminate the need for
2766 retakes, and that technique charts provided by manufacturers be reviewed for proper sensor
2767 placement.
2768
58
-------
DRAFT PROPOSAL
2769 In clinics or field use environments where film is still used, the fastest appropriate film should be
2770 used. For periapical and bite-wing radiographs, only films of American National Standard
2771 Institute Speed Group "F" or faster are recommended (NCRP 2003). Since there are minimal
2772 diagnostic differences between the various intraoral films available in 2012, the use of faster
2773 films (E- or F-speed) is preferred because they reduce the radiation dose by more than 50% when
2774 compared with D-speed film.
2775
2776 When panoramic and other extraoral projections are taken, it is recommended that high speed
2777 films be matched to their rare earth intensifying screens. The higher speed of the rare earth
2778 screen-film combinations (400 or higher system speed) are twice as fast as conventional calcium
2779 tungstate screen-film combinations with equivalent diagnostic value at 1/2 to 1/4 the dose to the
2780 patient (Miles et al. 1989).
2781
2782 It is imperative that the operator's manual for all imaging acquisition hardware is readily
2783 available to the user, and that the equipment is operated and maintained following the
2784 manufacturer's instructions, including any appropriate adjustments for optimizing dose and
2785 image quality.
2786
2787 Leaded aprons were recommended for dentistry when dental x-ray equipment was poorly
2788 collimated, unfiltered, and films were much slower than those available in 2012. Given the
2789 advent of good collimation, filtration, direct current x-ray machines, faster film speeds, and
2790 digital sensors, gonadal and effective doses resulting from scatter radiation are extremely low
2791 and are not significantly reduced by the use of the leaded aprons. According to NCRP Report
2792 No. 145 , technological advancements have eliminated the requirement for lead aprons on
2793 patients when all of the following recommendations are followed: a 60-80 kVp intraoral
2794 exposure unit is used, the source-to-image receptor distance for intraoral radiography is between
2795 20-40 cm, a rectangular collimator is used for intraoral radiographs, and a minimum of E-speed
2796 equivalent exposure film/sensors is used. It is not unreasonable to have aprons available for
2797 patients who request their use (NCRP 2003).
2798
2799 The thyroid gland is among the most sensitive organs to radiation-induced tumors, especially in
2800 children. NCRP Report No. 145 states that, "thyroid shielding shall be provided for children, and
2801 should be provided for adults, when it will not interfere with the examination" (NCRP 2003).
2802 These recommendations may be relaxed in the cases where anatomy or the inability of the
2803 patient to cooperate makes beam-receptor alignment awkward. The positive project! on-angle of
2804 the panoramic x-ray beam of+4° to +7 ° essentially eliminates thyroid dose.
2805
2806 Protective aprons and thyroid shields should be hung or laid flat and never folded, and
2807 manufacturer's instructions should be followed. All protective shields should be evaluated for
2808 damage (e.g., tears, folds, and cracks) at least annually using visual and manual inspection
2809 (Miller et al. 2010b). If a defect in the attenuating material is suspected, radiographic or
2810 fluoroscopic inspection may be performed as an alternative to immediately removing the item
2811 from service. Consideration should be given to minimizing the radiation exposure of inspectors
2812 by minimizing unnecessary fluoroscopy.
2813
59
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DRAFT PROPOSAL
2814 As of 2012, hand-held, battery-powered x-ray systems are available for intra-oral radiographic
2815 imaging. The hand-held exposure device is activated by a trigger on the handle of the device.
2816 Device operation, at first glance, poses several concerns, which appear inconsistent with
2817 previously established dental radiological protection guidelines. These concerns include: (1) the
2818 x-ray tube assembly is hand-held by the operator rather than wall mounted, (2) the trigger for x-
2819 ray exposure is on the hand-held device and not remotely located away from the source of
2820 radiation, and (3) the operator does not stand behind a barrier. However, dosimetry studies
2821 indicate that these hand-held devices present no greater radiation risk than standard dental
2822 radiographic units to the patient or the operator (Goren et al. 2008; Masih et al. 2006; Witzel
2823 2008). No additional radiation protection precautions are needed when the device is used
2824 according to the manufacturer's instructions. These include: (1) holding the device at mid-torso
2825 height, (2) orienting the shielding ring properly with respect to the operator, and (3) keeping the
2826 cone as close to the patient's face as practical. If the hand-held device is operated without the
2827 ring shield in place, it is recommended that the operator wear a lead apron.
2828
2829 All operators of hand-held units should be instructed on their proper storage. Due to the portable
2830 nature of these devices, they should be secured properly when not in use to prevent accidental
2831 damage, theft or operation by an unauthorized user. Hand held units should be stored in locked
2832 cabinets, locked storage rooms or locked work areas when not under the direct supervision of an
2833 individual authorized to use them. Units with user-removable batteries should be stored with the
2834 batteries removed. Records listing the names of approved individuals who are granted access
2835 and use privileges should be prepared and kept current.
2836
2837 Testing and Quality Assurance
2838
2839 Quality assurance refers to those steps that are taken to make sure that a dental facility or
2840 imaging facility consistently produces images that are adequate for the purpose with optimal
2841 patient and minimal operator exposure. Quality assurance may be divided into two major
2842 categories: quality administration and quality control. Quality administration refers to the
2843 management aspect of a quality assurance program. It includes those organizational steps taken
2844 to make sure that testing techniques are properly performed and that the results of tests are used
2845 to effectively maintain a consistently high level of image quality. An effective program includes
2846 assigning personnel to determine optimum testing frequency of the imaging devices, evaluate
2847 test results, schedule corrective action, provide training, and perform ongoing evaluation and
2848 revision of the quality assurance program.
2849
2850 Quality control comprises the procedures used for the routine physical testing of the primary
2851 components of the dental imaging chain from the x-ray machine, through processing, to the
2852 viewing of dental images. Quality control measures are listed in Table 2. Each facility, through
2853 its radiation quality control team (e.g. health physicist, medical physicist, biomedical
2854 maintenance personnel), needs to track maintenance and monitoring procedures. Dental clinics
2855 that use film should evaluate film processing darkrooms and daylight loaders for light leaks and
2856 safelight performance.
2857
2858
60
-------
DRAFT PROPOSAL
2859 Personnel
2860
2861 As in general medical radiology, it is important to eliminate unproductive radiation exposure in
2862 dentistry; thus, privileges to order dental x-ray examinations should be limited to Doctors of
2863 Dental Surgery or Dental Medicine who are eligible for licensure in the United States or one of
2864 its territories or commonwealths. Exception may be granted for persons in post graduate training
2865 status under the supervision of a person meeting such requirements. Variances to the above
2866 qualification requirements should occur only for emergency or life-threatening situations, such as
2867 natural disasters. Also, non-peacetime operations in the field or aboard ship could require such
2868 variances. Dental equipment operators should receive appropriate education and training in the
2869 areas of anatomy, physics, technique and principles of radiograph! c exposure, radiation
2870 protection, radiographic positioning, and image processing that are relevant to dental imaging.
2871 Proficiency can be demonstrated by satisfying existing state certification programs for dental
2872 auxiliaries. Also, proficiency can be improved by reviewing dental radiology practice
2873 recommendations from the American Dental Association.
2874
2875 Operators of dental x-ray equipment may be exposed to primary radiation in the useful beam,
2876 leakage radiation from the tube housing, and scattered radiation. Operator protection measures
2877 are required to minimize their occupational exposure. There are three basic methods to reduce
2878 the occupational dose from x-rays: position, distance, and shielding. The most effective way of
2879 reducing operator exposure to primary radiation is to enforce strict application of the position
2880 and distance rule (i.e., the operator should stand at least 2 m (6 ft) away from the tube head of
2881 the dental x-ray generator). If the operator cannot stand at least this far from the patient during
2882 the exposure, he or she should stand behind an appropriate barrier or outside the operatory
2883 behind a wall. In clinics or field situations, where the operator is required to be in the immediate
2884 exposure area, the operator should be positioned at the location of minimum exposure. This
2885 location, also known as the safe quadrant, is at an angle between 90 and 135° to the primary
2886 beam. Dental personnel should not hold image receptors in patients' mouths. If a patient has to
2887 be restrained during exposure, a relative or friend of the patient should do so. The relative or
2888 friend may be provided a lead apron and latex gloves if the image receptor is to be held in the
2889 mouth so they have protection during exposure.
2890
2891 In panoramic imaging, scattered radiation is typically low due to the narrow beam of radiation
2892 and the shielding incorporated into the cassette carrier. With a typical workload, operators can
2893 produce panoramic images without the use of shielding as long as they are at least 2 meters (6
2894 feet) from the unit. An appropriate shield should be used if this distance cannot be maintained.
2895
2896 Structural shielding criteria are provided by NCRP (NCRP 2003). Only a qualified individual
2897 (preferably a qualified physicist) can determine how much shielding is needed for a given
2898 situation. The walls of the dental x-ray operatory must provide sufficient attenuation to limit the
2899 exposure of other individuals to permissible levels. Usually, it is not necessary to line the walls
2900 with lead to meet this requirement when intraoral or panoramic equipment is used. A wall
2901 constructed of gypsum wall board (drywall) has been determined to be sufficient for use of this
2902 equipment in the average dental office (MacDonald et al. 1983).
2903
61
-------
DRAFT PROPOSAL
2904 Any individual who is likely to exceed a designated fraction of the regulatory dose limit shall be
2905 enrolled in a radiation monitoring program (OSHA 2012; USNRC 2012c). Historically, dental
2906 radiation workers have not approached these limits and have not required dosimetry when good
2907 radiation practices have been used. To determine if dosimeters are required, evaluations of
2908 occupational dose should be conducted by a qualified physicist when a program is initiated,
2909 facilities are significantly modified, or equipment or processes change. The evaluation may
2910 consist, for example, of monitoring personnel for a period of time or assessing the radiation field
2911 around the equipment. With regard to workers who have declared their pregnancy, NCRP
2912 Report No. 145 states that "Personal dosimeters shall be provided for known pregnant
2913 occupationally-exposed personnel" (NCRP 2003).
2914
2915 Procedures
2916
2917 Justification applies to imaging in dentistry. The number of images obtained should be the
2918 minimum necessary to obtain essential diagnostic information. Dental radiographs should be
2919 prescribed only following an evaluation of the patient's needs that includes a health history
2920 review, a clinical dental history assessment, a clinical examination and an evaluation of
2921 susceptibility to dental diseases. A full mouth survey or panoramic radiograph of the teeth and
2922 jaw structure may be justified for forensic purposes for military personnel. Postoperative
2923 radiographs should be taken only when there is clinical indication and not as verification for
2924 third-party payment plans. This is consistent with the recommendations of the Food and Drug
2925 Administration and the American Dental Association (ADA FDA 2004; NCRP 1990). In cases
2926 where emerging new dental imaging technologies are used by physicians for non-dental
2927 evaluations, these physicians should request these studies through their medical imaging ordering
2928 procedures as determined by their local facility.
2929
2930 Optimization also applies to imaging in dentistry. In order to achieve lower exposures, the
2931 operator's manual should be readily available to the user, and the equipment should be operated
2932 following the manufacturer's instructions, including any appropriate adjustments for optimizing
2933 dose and ensuring adequate image quality. The x-ray machine should be operated at the highest
2934 kilovoltage (kVp) adequate for diagnosis. An image receptor holding device should be used for
2935 proper film, photostimulable phosphor (PSP) plates, or sensor positioning whenever possible.
2936 Technique charts provided by manufacturers should be reviewed for proper image receptor
2937 placement. Protocols may be relaxed in the cases where anatomy or the inability of the patient to
2938 cooperate makes beam-receptor alignment awkward.
2939
2940 Cone beam computed tomography (CBCT) is used for dental implant planning, orthodontics,
2941 surgical assessment of pathology, pre- and postoperative assessment of craniofacial fractures,
2942 and temporomandibular joint assessment. CBCT provides high-resolution computed
2943 tomographic images with short scanning times (approximately 20 seconds) and high geometric
2944 accuracy (actual size of item imaged without distortion) (Scarfe et al. 2006). The major
2945 advantage of CBCT over multi-row detector computed tomography systems (MDCT) is the
2946 lower radiation dose . CBCT scanners utilize a narrow, collimated cone beam of radiation that
2947 scans both the maxilla and mandible at one time. The effective dose of a CBCT examination is
2948 approximately 7 times greater than a panoramic image but only 2-5% of a conventional CT of
2949 the same region (Scarfe et al. 2006). Given these low radiation doses, the same radiation
62
-------
DRAFT PROPOSAL
2950 protection guidelines recommended for conventional dental imaging should be implemented for
2951 CBCT.
2952
63
-------
DRAFT PROPOSAL
2953 VETERINARY
2954
2955 Diagnostic radiology is an essential part of present-day veterinary practice. The typical imaging
2956 workload in a veterinary practice is low on the average; however, certain practices unique to
2957 veterinary radiology can expose the staff at a greater rate than typical operators. In veterinary
2958 medicine, the possibility that anyone may be exposed to enough radiation to create deterministic
2959 effect is extremely remote.
2960
2961 There are two main aspects of the problem to be considered. First, personnel working with x-ray
2962 imaging equipment should be protected from excessive exposure to radiation during their work.
2963 Secondly, personnel in the vicinity of veterinary radiology facilities and the general public
2964 require adequate protection (NCRP 2004b; OSHA 2012; USNRC 2012c).
2965
2966 Equipment
2967
2968 The recommendations pertaining to the use of medical radiographic equipment and shielding
2969 requirements for humans apply to the use of similar equipment in veterinary medicine. The
2970 following points are highlighted for veterinary applications:
2971
2972 1. In a fixed facility, the floors, walls, ceilings and doors should be built with materials
2973 providing adequate radiation protection to workers.
2974 2. The shielding should be constructed to form an unbroken barrier.
2975 3. In a fixed facility, a control booth should be provided for the protection of the operator.
2976 Mobile protective barriers are not considered adequate as a control booth except for
2977 facilities requiring no shielding at 1 meter from source, or where 1/20 of permissible dose
2978 equivalent limits are not likely to be exceeded at 1 meter.
2979 4. The control booth should be located, whenever possible, such that the radiation has to be
2980 scattered at least twice before entering the booth. In facilities where the radiation beam
2981 may be directed toward the booth, the booth becomes a primary barrier and should be
2982 shielded accordingly.
2983 5. The control booth should be positioned so that during an irradiation no one can enter the
2984 radiographic room without the knowledge of the operator.
2985 6. Required warning signs should be posted on all entrance doors of each x-ray imaging room.
2986 7. Mobile x-ray equipment used routinely in one location is considered to be a fixed
2987 installation, and the facility should be shielded accordingly.
2988 8. Protective aprons, gloves and thyroid shields used for veterinary x-ray examinations should
2989 provide attenuation equivalent to at least 0.5 mm of lead-equivalence at x-ray tube voltages
2990 of up to 150 kVp. Protection should be provided throughout the glove, including fingers
2991 and wrist. Further discussion is provided in the section on RADIATION SAFETY
2992 PROCEDURES FOR FLUOROSCOPY.
2993
2994
2995 An addition to the diagnostic veterinary imaging inventory as of 2012 is hand-held, battery-
2996 powered x-ray systems which have been developed for radiographic imaging. The hand-held
2997 exposure device is activated by a trigger in the handle of the device by the operator. This
2998 technology, at first glance, poses several concerns, which appear inconsistent with previously
64
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DRAFT PROPOSAL
2999 established radiological protection guidelines. The first concern is that the x-ray tube assembly
3000 is hand-held by the operator rather than wall mounted. The second concern is that the trigger for
3001 x-ray exposure is within the hand-held device and not remotely located away from the source of
3002 radiation. The final concern is that the operator does not stand behind a barrier. These concerns
3003 arise from previous guidelines that were established to: 1) protect the operator from possible
3004 radiation leakage from the housing of the device; 2) protect the operator from backscatter from
3005 the patient; and 3) protect the patient from excessive radiation or repeat exposures when
3006 inadequate image quality results from movement of the hand-held x-ray generator.
3007
3008 For additional information, see the veterinary section below on SPECIAL PROCEDURES FOR
3009 PORTABLE HAND-HELD SYSTEMS.
3010
3011 Testing and Quality Assurance
3012
3013 Since veterinary equipment is generally identical to medical equipment all the quality assurance
3014 tasks associated with medical equipment can be applied to veterinary equipment; however, based
3015 on the typical workload a reduced quality assurance program is probably warranted in most
3016 cases. Atypical testing and QA program would consist of at least the following:
3017 1. It is essential that a radiation safety survey be completed on all new veterinary x-ray
3018 equipment by or under the direction of a qualified expert. As stated in NCRP Report No.
3019 148, "Resurveys shall be made following replacement of irradiation equipment, or
3020 modifications that could change the radiation source, whenever the workload increases
3 021 significantly, or if other operating conditions are modified that could affect the radiation
3022 dose in occupied areas. Resurveys are required after the installation of supplementary
3023 shielding to determine the adequacy of the modification" (NCRP 2004b).
3024 2. Prior to the first use of a mobile fluoroscope, a radiation exposure survey should be done
3025 with the x-ray beam and maximum operating potential and with an appropriate test
3026 phantom in place to determine the perimeter of the area within which individuals without
3027 radiation protection apparel should not be present (NCRP 2004b).
3028 3. Reduce radiation exposure to the animal patient, operator, and members of the public by
3029 minimizing the need for repeat exposures because of inadequate image quality (NCRP
3030 2004b).
3031 4. For film-based systems, a sensitometry and densitometry test should be done each day the
3032 system is used in order to ensure consistent operation. A step wedge test may be used as a
3033 substitute for the standard sensitometry and densitometry test.
3034 5. Darkroom fog or darkroom integrity should be evaluated biannually. This may be
3035 especially relevant if the darkroom is not a single use room.
3036 6. It is strongly recommended that lead personnel protective equipment (e.g., aprons, gloves,
3037 thyroid collars) be evaluated at least annually for lead protection integrity using visual and
3038 manual inspection (Miller et al. 2010b; NCRP 2010). If a defect in the attenuating material
3039 is suspected, radiographic or fluoroscopic inspection may be performed as an alternative to
3040 immediately removing the item from service. Consideration should be given to minimizing
3041 the radiation exposure of inspectors by minimizing unnecessary fluoroscopy.
3042
3043
65
-------
DRAFT PROPOSAL
3044 Personnel
3045
3046 Veterinary x-ray equipment operators, similar to medical x-ray equipment operators, should
3047 receive appropriate education and training in the areas of anatomy, physics, technique and
3048 principles of radiograph! c exposure, radiation safety, radiographic positioning, and image
3049 processing that are relevant to veterinary imaging. Only personnel with specific, appropriate
3050 training should be permitted to operate x-ray equipment. It is strongly recommended that the
3051 veterinary medical application of x-ray equipment be performed only by or under the general
3052 supervision of a veterinarian properly trained and credentialed to operate such equipment.
3053 Individuals who routinely use veterinary radiologic equipment need a basic understanding of the
3054 following:
3055
3056 1. animal positioning techniques to allow for minimal radiation exposure for employees;
3057 2. basic principles and concepts of radiation in general and x-radiation in particular;
3058 3. component parts/workings of the x-ray machine and the production of x-rays;
3059 4. factors affecting the quality of the x-ray beam and the radiographic image;
3060 5. effects of ionizing radiation on living tissues;
3061 6. radiation bioeffects, health, and safety;
3062 7. radiation protection procedures for the operator and the patient;
3063 8. selection of appropriate imaging surveys, image receptor types, duplicating, and record
3064 keeping;
3065 9. technique of proper image processing, handling, and record keeping;
3066 10. viewing techniques and principles of interpretation;
3067 11. digital imaging and alternate imaging modalities;
3068 12. appearances of normal radiographic landmarks, artifacts, and shadows; and
3069 13. requirements for monitoring and documenting staff occupational radiation exposure.
3070
3071 Procedures
3072
3073 The procedures pertaining to the use of veterinary radiography are generally equivalent to
3074 procedures for medical (human) radiography. The following recommendations will minimize
3075 the dose to veterinary facility staff and clients from veterinary diagnostic radiographic
3076 procedures. All suggestions will secondarily minimize the dose to the radiation operator and
3077 consequently, the results may be considered as a double benefit to the patient and the worker.
3078 The guidelines and procedures outlined in this section are primarily directed toward occupational
3079 health protection. Adherence to these guidelines will also provide protection to visitors and
3080 other individuals in the vicinity of an x-ray facility. However, the safe work practices and
3081 procedures for using various types of x-ray equipment should be regarded as a minimum to be
3082 augmented with additional requirements, when warranted, to cover special circumstances in
3083 particular facilities. To achieve optimum safety, operators should make every reasonable effort
3084 to keep exposures to themselves and to other personnel as low as reasonably achievable.
3085
3086 Veterinary clinic setup
3087
3088 1. An x-ray room should be used for only one x-ray procedure at a time.
66
-------
DRAFT PROPOSAL
3089 2. All entrance doors to an x-ray room should be kept closed while a radiographic procedure is
3090 being performed.
3091 3. Where a control booth or protective barrier is available, it is strongly recommended that
3092 operators remain inside or behind when making an irradiation. If a control booth or
3093 protective screen is not available, the operator should always wear protective clothing.
3094 4. When film screen imaging is used, the fastest combination of films and intensifying screens
3095 consistent with diagnostically acceptable results and within the capability of the equipment
3096 should be used.
3097 5. When digital x-ray imaging is used, procedures should be established to prevent
3098 excessively high doses, also known as dose creep, as addressed in the radiography section
3099 of this document.
3100
3101 Personal protective equipment
3102
3103 1. Personnel should use protective devices, as appropriate.
3104 2. Protective aprons, gloves and thyroid shields should be hung or laid flat and never folded,
3105 and manufacturer's instructions should be followed.
3106 3. Armored gloves (welding gloves) should be used to restrain fractious animals. Since lead-
3107 lined gloves will not protect against bites that could puncture the lead, the radiation
3108 protection provided by the garment may be compromised (NCRP 2004b).
3109
3110 Animal restraint
3111
3112 1. If necessary, the animal should be sedated or holding devices used during radiography.
3113 However, if this is not possible and a person must restrain the animal, that person should
3114 wear appropriate radiation protective equipment (aprons, gloves, etc.) and avoid direct
3115 irradiation by the primary x-ray beam. No person should routinely hold animal patients
3116 during x-ray examinations (NCRP 2004b).
3117 2. Individuals under the age of 18 and pregnant or potentially pregnant women should not be
3118 permitted to hold animals during radiography.
3119
3120 Use of x-ray equipment
3121
3122 1. X-ray equipment should be operated only by or under the direct supervision of qualified
3123 individuals.
3124 2. X-ray machines that are energized and ready to produce radiation should be supervised.
3125 3. The x-ray room should contain only those persons whose presence is essential when a
3126 radiological procedure is carried out.
3127 4. The radiation beam should always be directed toward adequately shielded or unoccupied
3128 areas.
3129 5. The radiation beam and scattered radiation should be attenuated as closely as possible to the
3130 source.
3131 6. Personnel should keep as far away from the x-ray beam as is practicable at all times (2 m).
3132 Exposure of personnel to the x-ray beam should never be allowed unless the beam is
3133 adequately attenuated by the animal and by protective clothing or barriers.
3134 7. A hand-held radiographic cassette or image receptor should not be used.
67
-------
DRAFT PROPOSAL
3135 8. For table-top radiography when the sides of the table are not shielded, a sheet of lead at
3136 least 1 mm in thickness and slightly larger than the maximum beam size should be placed
3137 immediately beneath the cassette or film.
3138 9. Veterinarians should not allow veterinary diagnostic radiation devices under their control to
3139 be used on human beings (NCRP 2004b).
3140 10. Technique charts should be developed for all animal types that are routinely radiographed.
3141
3142 Personal dosimetry
3143
3144 1. The workload in a typical veterinary clinic may not be sufficient to require the issuance of
3145 personal dosimetry; however, a qualified expert should be consulted for a clinic's particular
3146 situation.
3147 2. Personal dosimetry should be worn in a manner that complies with regulatory requirements
3148 and ensures that radiation doses can be determined accurately. See the section on
3149 PERSONNEL AND AREA MONITORING.
3150 3. Occupational radiation dose limits in veterinary and human medical practice should be the
3151 same. See the section on PERSONNEL AND AREA MONITORING.
3152
3153 Special procedures for portable hand-held systems
3154
3155 1. Portable hand-held x-ray systems should be used as outlined in the instructions that come
3156 with the unit. Exposures using this unit should be made only when the area adjacent to the
3157 clinical area is free of all individuals not directly involved in the imaging procedure. When
3158 standard radiology protocols are utilized according to manufacturer instructions, with the
3159 ring shield in place, there is no indication for additional radiation protection
3160 recommendations.
3161
3162 2. Portable hand-held x-ray systems use essentially the same amount of radiation as
3163 traditional wall mounted x-ray units since the amount of radiation needed to generate an
3164 adequate image is determined by the image receptor, not by the x-ray device. Radiation
3165 safety criteria for operators of the hand-held device should be the same as mentioned
3166 earlier for conventional exposure systems.
3167
3168 3. All operators of these units should be instructed on its proper storage. Due to the portable
3169 nature of the hand-held device, it should be secured properly when not in use to prevent
3170 accidental damage, theft or operation by an unauthorized user. Hand held units should be
3171 stored in locked cabinets, locked storage rooms or locked work areas when not under the
3172 direct supervision of an individual authorized to use them. Units with user-removable
3173 batteries should be stored with the batteries removed. Records listing the names of
3174 approved individuals that are granted access and use privileges should be prepared and kept
3175 current (quarterly revi ew).
3176
68
-------
DRAFT PROPOSAL
3177 MEDICAL IMAGING INFORMATICS
3178
3179 Digital information systems are used for the ordering, scheduling, tracking, processing, storage,
3180 transmission, and viewing of imaging studies and providing the reports of study interpretations.
3181 These systems should be used to the greatest extent possible. They include picture archiving and
3182 communication systems (PACSs), teleradiology systems, radiology information systems,
3183 hospital information systems, and the Electronic Health Record (Congress 2007). For efficiency
3184 of workflow, these systems do not operate independently, but instead are connected to the
3185 imaging devices and each other by computer networks and exchange information in accordance
3186 with standards such as TCP/IP (Transmission Control Protocol/Internet Protocol, or the Internet
3187 protocol suite), DICOM, HL7, and ME. These information systems are complex and will not be
3188 discussed in detail in this report. However, there are certain aspects of these systems that
3189 indirectly can affect the radiation doses to patients from imaging studies. Proper planning,
3190 design, management, and use of these systems can help avoid performing unnecessary or
3191 inappropriate studies and repeat studies. These systems can also help in monitoring doses to
3192 patients and image receptors and monitoring retakes; the information from this monitoring can
3193 help in optimizing doses from imaging procedures.
3194
3195 These information systems can help avoid the ordering of unnecessary or inappropriate imaging
3196 studies. At the time that a Referring Medical Practitioner places the order for an imaging study,
3197 the system can provide decision support regarding the appropriateness of the study for the
3198 particular patient and notification of alternatives that may impart less or no radiation. These
3199 information systems can also notify the Referring Medical Practitioner of previously acquired
3200 studies that may render an additional imaging study unnecessary.
3201
3202 The inability to retrieve an imaging study can create the need for a repeat study. These digital
3203 information systems and procedures for their use should be designed to protect against data loss.
3204 Such measures should include administrative, physical, and technical safeguards, including
3205 storing information on stable media, ensuring the storage location is secure from natural and
3206 human threats, ensuring the stored information is secure from deliberate or accidental erasure or
3207 modification, storing duplicate backup copies of the information on media in a remote location
3208 or locations, and precautions against loss of information from media wear and aging and media
3209 obsolescence. Additionally, the facility should have a disaster plan in place to guide operations
3210 when the network is inoperable or power outage affects operation of the PACS system. It is the
3211 responsibility of the institution to meet the records retention, security, privacy, and retrieval
3212 requirements of its agency and other Federal requirements (e.g., HIPAA and associated Federal
3213 regulations) (ACR 2007c; ACR 2009a; DHHS 2012b), and to address the aforementioned issues.
3214
3215 These systems also provide an important quality assurance function. They should facilitate
3216 monitoring of patient dose indices, the doses to radiographic image receptors, and the
3217 number of retakes and inadequate images. This requires both capture and storage of this
3218 information and appropriate software tools for data analysis and display. Equipment
3219 manufacturers should be encouraged to work with professional societies and standards
3220 organizations to develop and implement standardized dose reporting systems. These
3221 systems should provide an estimate of patient radiation dose that is accurate for the
3222 individual, available in real time to the operator, and documented for the individual
69
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DRAFT PROPOSAL
3223 patient. These systems should also be capable of transmitting de-identified patient
3224 radiation dose data to a central dose registry. To this end, Federal facilities should give
3225 preference to equipment with these standardized dose reporting systems when making
3226 purchasing decisions.
3227
70
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DRAFT PROPOSAL
3228 SUMMARY AND RECOMMENDATIONS FOR FACILITY ACTION
3229
3230 GENERAL
3231
3232 1. Each facility should establish a formal mechanism whereby Referring Medical Practitioners
3233 have sources of information available at the time of ordering regarding appropriate
3234 diagnostic imaging methods to answer the clinical question and to optimize ionizing
3235 radiation dose to the patient. These may include decision support software or
3236 appropriateness criteria. A mechanism for consultation with Radiological Medical
3237 Practitioners should also be made available.
3238 2. The Universal Protocol should always be followed to ensure the right patient gets the right
3239 procedure.
3240 3. Physicians and staff should always strive to limit patient irradiation to that necessary to
3 241 perform the procedure.
3242 4. Facilities involved in health care delivery should ensure that operators of medical imaging
3243 equipment that use x-rays: 1) are adequately trained to produce acceptable quality images,
3244 2) know how to produce these images with appropriate patient doses, and 3) periodically
3245 demonstrate continuing competence.
3246 5. Facilities should ensure that the operator's manual is readily available to the user, and the
3247 equipment is operated following the manufacturer's instructions, including any appropriate
3248 adjustments for optimizing dose and ensuring adequate image quality.
3249 6. Facilities should establish a formal mechanism whereby Radiological Medical Practitioners
3250 are available to consult with Referring Medical Practitioners regarding the optimal
3251 diagnostic imaging method to answer the clinical question while minimizing ionizing
3252 radiation dose to the patient.
3253 7. Facilities should use equipment that provides relevant patient dose information. This
3254 equipment should allow the facility to program in dose alerts to inform operators if selected
3255 operating parameters might produce a radiation dose exceeding that recommended by the
3256 facility.
3257 8. Facilities should use the dose information from individual patient imaging procedures that
3258 is provided by imaging equipment as part of the quality assurance program for identifying
3259 opportunities to reduce dose. .
3260 9. Facilities should use reference levels as a quality improvement tool by collecting and
3261 assessing radiation dose data. Each facility should also submit its radiation dose data to a
3262 national registry, if and when such a registry is available.
3263 10. Facilities should be aware of upgrades to software and hardware of x-ray imaging systems
3264 that enhance safety. These should be evaluated and considered for implementation.
3265 11. Facilities should assess the radiation exposure of workers and provide periodic feedback to
3266 them. In addition, each worker who is expected to receive more than 10% of the applicable
3267 dose limit should be required to wear one or more dosimeters.
3268
3269 BONE DENSITOMETRY
3270
3271 1. Facilities should establish a range of acceptable precision performance and ensure each
3272 technologist is trained and meets this standard.
71
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DRAFT PROPOSAL
3273 2. The facility should ensure that patients imaged for precision and cross-calibration studies
3274 should be representative of the facility's patient population
3275 3. Facilities should ensure that practitioners who interpret bone densitometry results are
3276 knowldegable in this field and not rely solely on a report produced by the equipment..
3277
3278 CHILDREN AND PREGNANT WOMEN
3279
3280 1. Facilities should ensure that when a monitored radiation worker declares her pregnancy she
3281 wears a dosimeter on the lower abdomen, underneath the apron at the level of the fetus.
3282 The dosimeter should be exchanged monthly. She should be issued this dosimeter unless
3283 such a dosimeter is already being worn.
3284 2. Children are more radiosensitive than adults. Facilities should ensure that technique and
3285 imaging protocols are appropriate for the child's size or weight to ensure adequate image
3286 quality and optimize radiation dose.
3287 3. In general, facilities should ensure that neither screening nor elective x-ray examinations
3288 are performed on pregnant women.
3289
3290 DENTISTRY
3291 1. Facilities should ensure that beam indicating devices are used with sensors, specific and
3292 ongoing training is given to orient operators on ways to eliminate the need for retakes, and
3293 technique charts provided by manufacturers are reviewed periodically for proper sensor
3294 placement.
3295 2. In clinics or field use environments where film may still need to be used, the fastest and
3296 most appropriate film should be used.
3297 3. In facilities where panoramic and other extraoral projections are obtained using film, it is
3298 recommended that high speed film be used and spectrally matched to its appropriate rare
3299 earth intensifying screen.
3300 4. An image receptor holding device for proper film, PSP or sensor positioning should be used
3301 whenever possible.
3302 5. Thyroid shielding shall be provided for children, and should be provided for adults, when it
3303 will not interfere with the examination (NCRP 2003).
3304 6. Dental clinics that use film should evaluate film processing darkrooms and daylight loaders
3305 for light leaks and safelight performance.
3306
3307 FLUOROSCOPY
3308 1. The facility's procedures should be written with the understanding that fluoroscopy can
3309 deliver a significant radiation dose to the patient, even when used properly.
3310 2. The facility should ensure that every person who operates or directs the operation of
3311 fluoroscopic equipment is trained in the safe use of the equipment.
3312 3. When a facility purchases fluoroscopic equipment, the additional cost of including dose-
3313 reduction technology is justified because the reduction in patient radiation dose can be
3314 considerable.
3315 4. Some types of fluoroscopic procedures have a potential for patient skin doses exceeding 2
3316 Gy. The facility should ensure that there are additional training requirements for operators
3317 and additional equipment requirements for these procedures.
72
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DRAFT PROPOSAL
3318 5. The facility should ensure that patient radiation dose data, including patient skin dose data
3319 when available, are recorded in the patient's medical record.
3320
3321 VETERINARY
3322
3323 1. Facilities should ensure that the veterinary medical application of x-ray equipment is
3324 performed only by or under the general supervision of a veterinarian properly trained and
3325 credentialed to operate such equipment.
3326 2. Facilities should ensure that individuals who routinely use veterinary radiographic
3327 equipment have a basic understanding of using medical x-rays and animal positioning
3328 techniques.
3329 3. Facilities should ensure that armored gloves (welding gloves) are used to restrain fractious
3330 animals since lead-lined gloves will not protect against bites that could puncture the lead.
3331 4. Facilities should have animal sedatives and holding devices available, and ensure they are
3332 used, if necessary.
3333 5. Facilities should not allow anyone to routinely hold animal patients during x-ray
3334 examinations.
3335 6. Facilities should not allow veterinary diagnostic radiation devices under their control to be
3336 used on human beings.
3337
3338 INFORMATICS
3339
3340 1. Patient safety requires that infrastructure exists for collecting, storing, and analyzing patient
3341 dosimetry data. Facilities should plan for longitudinal tracking of patient radiation doses.
3342 This planning should address the data acquisition, networking, storage, analysis, and
3343 security requirements of existing and planned future diagnostic devices.
3344 2. Digital information systems should be used in Federal facilities to the greatest extent
3345 possible.
3346 3. Facilities should give preference to equipment with standardized dose reporting systems
3347 when making purchasing decisions.
3348 4. Facilities should ensure that their health professionals use digital information systems, to
3349 help avoid the ordering of unnecessary or inappropriate imaging studies.
3350
3351 INFORMED CONSENT
3352
3353 Federal facilities should ensure that, except in emergency situations, informed consent is
3354 obtained from the patient or the patient's legal representative and is appropriately
3355 documented prior to the initiation of any procedure that is likely to expose the patient, or
3356 fetus if the patient is pregnant, to significant risks and potential complications.
3357
3358 PRESCRIPTION
3359
3360 Facilities should ensure that appropriate information is obtained and reviewed at the time of
3361 ordering/prescribing to optimize the choice of study and protocol, and to optimize the dose.
3362
73
-------
DRAFT PROPOSAL
3363 REFERENCE LEVELS
3364
3365 1. Reference levels are dose values for a standard phantom or actual patient for specific
3366 procedures measured at a number of representative clinical facilities. Facilities should use
3367 reference levels as quality assurance and quality improvement tools.
3368 2. National reference levels that are specific for the U.S. population should continue to be
3369 developed. The on-going nationwide collection of these data from government and non-
3370 government facilities, such as by NEXT and ACR, is essential to this effort. Facilities
3371 should submit radiation dose data to a national registry, if and when available.
3372 3. Facilities should ensure that a representative sampling and assessment of exposure
3373 indicators from each modality is performed at least annually, but preferably quarterly. It
3374 should be reviewed by the chief technologist. This effort should be performed under the
3375 guidance of a qualified physicist.
3376 4. If the mean radiation dose at the facility exceeds the reference level, the facility should
3377 investigate as appropriate to reduce radiation dose. If the mean radiation dose is
3378 significantly lower than the reference level, the facility should evaluate image quality.
3379 5. If local practice at a facility results in a mean radiation dose that is greater than the RL, the
3380 facility should investigate the equipment. If the equipment is functioning properly and
3381 within specification, operator technique and procedure protocols should be examined.
3382
74
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3383
3384
3385
3386
3387
3388
3389
3390
3391
3392
3393
3394
3395
3396
3397
3398
3399
3400
3401
3402
3403
3404
3405
3406
3407
3408
3409
3410
3411
3412
3413
3414
3415
3416
3417
3418
3419
3420
3421
3422
3423
3424
3425
3426
3427
3428
AAPM
ACC
ACCF
ACGME
ACR
ACS
ADA
AEC
AHA
ALARA
AMA
ANSI
AOA
AOBR
ARRT
ATSDR
BEIR
BID
BMD
CBCT
CFR
CIRSE
cm
CNMT
CR
CRCPD
CT
CTDI
CTDIvol
DAP
DC
DDM
DDR
DOS
DEXA
DHHS
DLP
DoD
DR
DRT
DXA
EHR
EPA
ESE
ACRONYMS AND ABBREVIATIONS
American Association of Physicists in Medicine
American College of Cardiology
American College of Cardiology Foundation
Accreditation Council for Graduate Medical Education
American College of Radiology
American Cancer Society
American Dental Association
automatic exposure control
American Heart Association
as low as reasonably achievable
American Medical Association
American National Standards Institute
American Osteopathic Association
American Osteopathic Board of Radiology
American Registry of Radiologic Technologists
Agency for Toxic Substances and Disease Registry
Biological Effects of Ionizing Radiation
beam indicating device
bone mineral density
cone beam computed tomography (cone beam CT)
Code of Federal Regulations
Cardiovascular and Interventional Radiology Society of Europe
centimeter
Certified Nuclear Medicine Technologist
computed radiography
Conference of Radiological Control Program Directors
computed tomography
computed tomography dose index
volumetric CTDI
dose area product (units are Gy-cm2)
direct current
Doctor of Dental Medicine
Direct digital radiography
Doctor of Dental Surgery
see DXA
Department of Health and Human Services
dose length product
Department of Defense
digital radiography
Diagnostic Radiologic Technologist
dual-energy x-ray absorptiometry (formerly DEXA)
Electronic Health Record
Environmental Protection Agency
entrance skin exposure
A-75
-------
3429
3430
3431
3432
3433
3434
3435
3436
3437
3438
3439
3440
3441
3442
3443
3444
3445
3446
3447
3448
3449
3450
3451
3452
3453
3454
3455
3456
3457
3458
3459
3460
3461
3462
3463
3464
3465
3466
3467
3468
3469
3470
3471
3472
3473
3474
ESEG
FDA
FGI
FGR
FOV
GI
GSD
Gy
HRS
ICRP
IEC
IRB
ISCD
ISCORS
KAP
kerma
kV
kVp
mA
mammo
mAs
MDCT
MQSA
mrem
mSv
NCI
NCRP
NEXT
NIH
OSHA
OSL
PACS
PET
PSD
PSP
RCIS
rem
RSO
RT(N)
SCAI
SPECT
SIR
SSD
Sv
entrance skin exposure guide
Food and Drug Administration
Fluoroscopically-guidedinterventional
Federal Guidance Report
field of view
gastrointestinal
genetically significant dose
gray (radiation dose, equal to 100 rem). Subunitis mGy (milligray)
Heart Rhythm Society
International Commission on Radiological Protection
International Electrotechnical Commission
Institutional Review Board
International Society for Clinical Densitometry
Interagency Steering Committee on Radiation Standards
kerma area product
kinetic energy released in matter (type of radiation measurement in air)
kilovolts
kilovolts potential (or kilovolts peak)
milliampere
mammography
milliampere-second
multi-row detector computed tomography (multi-detector CT)
Mammography Quality Standards Act
millirem
millisi evert
National Cancer Institute
National Council on Radiation Protection and Measurements
Nationwide Evaluation of X-ray Trends
National Institutes of Health
Occupational Safety and Health Administration
optically stimulated luminescence
picture archiving and communication system
positron emission tomography
position-sensitive x-ray detection
photostimulable phosphor
Registered Cardiovascular Invasive Specialists
Traditional radiation unit for equivalent dose (product of absorbed dose [rad] and
radiation weighting factor). Subunit is mrem (millirem) or jirem (microrem)
Radiation Safety Officer
Radiological Technologist Nuclear qualification
Society for Cardiac Angiography and Intervention
single particle emission computed tomography
Society of Interventional Radiology
source-to-skin distance
sievert (SI radiation unit for equivalent dose or effective dose). Subunit is mSv
(millisievert) or jiSv (micro si evert)
76
-------
3475 TLD thermoluminescent dosimeter
3476 USPSTF United States Preventive Services Task Force
3477 USN United States Navy
3478 VA US Department of Veterans Affairs
3479
77
-------
3480 GLOSSARY
3481
3482 Acceptance test - a test carried out after new equipment has been installed or major
3483 modifications have been made to existing equipment, in order to verify compliance with the
3484 manufacturer's specifications, contractual specifications, and applicable local regulations or
3485 equipment standards
3486 Adequate image - an image that provides the information needed to answer the clinical question
3487 at an optimized dose, i.e., the lowest dose possible to produce that image
3488 Adequate image quality - image quality sufficient for the clinical purpose. Whether the image
3489 quality is adequate depends on the modality being used and the clinical question being asked.
3490 ALARA (as low as reasonably achievable) - a principle of radiation protection philosophy that
3491 requires that exposures to ionizing radiation be kept as low as reasonably achievable,
3492 economic and social factors being taken into account. The protection from radiation exposure
3493 is ALARA when the expenditure of further resources would be unwarranted by the reduction
3494 in exposure that would be achieved.
3495 Ancillary personnel - personnel beyond the operational medical staff who provide support
3496 services
3497 Angiography - radiography of vessels after the inj ection of a radiopaque contrast material;
3498 usually requires percutaneous insertion of a radiopaque catheter and positioning under
3499 fluoroscopic control (Stedman 2006)
3500 Attenuation - reduction in radiation intensity, such as via the use of shielding
3501 Backscatter (as opposed to scatter) - a Compton scattering event in which a photon strikes an
3502 object and deflects at an angle greater than 90°, i.e., in a direction back toward its source
3503 Beam indicating device (BID) - a lead lined tube attached to an x-ray tube head through which
3504 the primary x-ray beam will travel, used by the operator, especially in a dental setting, to align
3505 the b earn with the i mage re ceptor
3506 Benefit - the probability or quantifiable likelihood that health will improve or deterioration will
3507 be prevented as a result of performing or not performing a medical procedure
3508 Benefitrisk ratio - a determination (possibly subjective) of the benefit to the patient from
3509 undergoing a procedure involving imaging using ionizing radiation compared with the risk to
3510 the patient from receiving a radiation dose associated with the consequent imaging.
3511 Maximizing the benefitrisk ratio involves balancing the benefitrisk ratio to the patient from
3512 an x-ray procedure against that from alternatives (e.g., ultrasound, MRI, or no action).
3513 Bone densitometry - the noninvasive measurement of certain physical characteristics of bone
3514 that reflect bone strength (typically reported as bone mineral content or bone mineral density)
3515 and used for diagnosing osteoporosis, estimating fracture risk, and monitoring changes in
3516 bone mineral content
3517 Collimator - a device used to reduce the cross-sectional area of the useful beam of photons or
3518 electrons with an absorbing material
3519 Computed radiography (CR; also see DR) - a projection x-ray imaging method in which a
3520 cassette houses a sensor plate rather than photographic film. This photo-stimulable phosphor -
3521 coated plate captures a latent image when exposed to x-rays and, when processed, releases
3522 light that is converted to a digital image.
3523 Computed tomography (CT) - an imaging procedure that uses multiple x-ray transmission
3524 measurements and a computer program to generate tomographic images of the patient (NCRP
3525 2000)
78
-------
3526 Cone - an open-ended device on a dental x-ray machine designed to indicate the direction of the
3527 central ray and to serve as a guide in establishing a desired source-to-image receptor distance
3528 (NCRP2000)
3529 Cone Beam Computed Tomography system (CBCT) - A digital volume tomography method
3530 used in some imaging applications using two dimensional digital detector arrays, and a cone-
3531 shape x-ray beam (instead of fan-shaped) that rotates around the patient to generate a high-
3532 resolution, 3D image, with high geometric accuracy. Reconstruction algorithms can be used
3533 to generate images of any desired plane.
3534 Credential - diploma, certificate, or other evidence of adequate educational performance that
3535 gives one a title or credit
3536 CTDIvoi - a radiation dose parameter derived from the CTDIW (weighted or average CTDI given
3537 across the field of view). The formula is:
3538 CTDUi = N-T-CTDIW /1, where
3539 N = number of simultaneous axial scans per x-ray source rotation,
3540 T = thickness of one axial scan (mm), and
3541 I = table increment per axial scan (mm).
3542 Deterministic effects - effects that occur in all individuals who receive greater than the threshold
3543 dose and for which the severity of the effect varies with the dose (NCRP 2003)
3544 Diagnosis - the determination of the nature of a disease, injury, or congenital defect (Stedman
3545 2006)
3546 Digital radiography (DR) - an x-ray imaging method (or radiography) which produces a digital
3 547 rather than film proj ection image. Includes both CR and DDR
3548 Direct digital radiography (DDR; also see CR and DR) - an x-ray imaging method in which a
3549 digital sensor, rather than photographic film, is used to capture an x-ray image. DDR is a
3550 cassette-less imaging method (providing faster acquisition time than cassette-based CR) using
3551 an electronic sensor that converts x-rays to electronic signals (charge or current) when
3552 exposed to x-rays.
3553 Dose - a measure of the energy deposited by radiation in a target. Used in this report as a
3554 generic term unless context refers to a specific quantity, such as absorbed dose, committed
3555 equivalent dose, committed effective dose, effective dose, equivalent dose or organ dose, as
3556 indicated by the context.
3557 Cumulative air kerma - sum of the kinetic energy released to a small volume of air at a
3558 specific point in space during a specified event or time frame when irradiation by an x-
3559 ray beam
3560 Cumulative dose - total radiation dose from all delivered to any specific organ or tissue
3561 Dose area product (DAP), also called kerma-area product (KAP) - the product of the air
3562 kerma and the area of the irradiated field and is measured in Gycm2, so it does not
3563 change with distance from the x-ray tube. A good measure of total energy delivered to
3 564 the patient, and of stochastic risk. Not a good indicator of deterministic risk
3565 Dose alert value - a value of CTDIvoi (in units of mGy) or of DLP (in units of mGycm)
3566 that is set by the operating institution to trigger an alert to the operator prior to
3567 scanning within an ongoing examination if it would be exceeded by an accumulated
3568 dose index, on acquisition of the next confirmed protocol element group. An alert
3569 value represents a value above which the accumulated dose index value would be well
3570 above the institution's established range for the examination that warrants more
3571 stringent review and consideration before proceeding, (see dose notification value)
79
-------
3572 Dose equivalent - the product of the absorbed dose at a point in the tissue or organ and
3 573 the appropriate quality factor for the type of radiation giving rise to the dose
3574 Dose length product (DLP) - an indicator of the integrated radiation dose from a
3575 complete CT examination. It addresses the total scan length by the formula DLP =
3576 CTDIvoi x scan length, with the units mGy-cm.
3577 Dose notification value - A value of CTDIvoi (in units of mGy) or of DLP (in units of
3578 mGycm) that is set by the operating institution to trigger a notification to the operator
3579 prior to scanning when exceeded by a corresponding dose index value expected for the
3580 selected protocol element. A notification value represents a value above which a dose
3581 index value would be above the institution's established range for the protocol
3582 element, (see dose alert value)
3583 Dose registry - see registry
3584 Effective dose - (E) - the sum of the weighted equivalent doses for the radiosensitive
3585 tissues and organs of the body. It is given by the expression E = ET (WT HT), in which
3586 HI is the equivalent dose in tissue or organ T and WT is the tissue weighting factor for
3587 tissue or organ T. The unit of E and HI is joule per kilogram (J kg"1), with the special
3588 name si evert (Sv) (see equivalent dose and tissue weighting factor).
3589 Equivalent dose (formerly dose equivalent) - (HT): the mean absorbed dose (DT) in a
3590 tissue or organ modified by the radiation weighting factor (WR) for the type and energy
3591 of the radiation. The quantity HT,R, defined as HT,R = WR • DT,R, where DT,R is the
3592 absorbed dose delivered by radiation type R averaged over a tissue or organ T and WR
3593 is the radiation weighting factor for radiation type R (IAEA 2011 a). The unit for HT is
3594 J kg"1, with the special name si evert (Sv).
3595 Reference point dose - radiation dose at the reference point, selected for reporting
3596 purposes, which is located at the center or in the central part of the planning target
3597 volume (PTV)
3598 Skin dose - radiation dose to the dermis
3599 Dosimeter - dose measuring device (NCRP 2003)
3600 Electronic Health Record (EHR) - an electronic record of health-related information on an
3601 individual that is created, gathered, managed, and consulted by authorized health
3602 professionals and staff (Congress 2007)
3603 Exposure - in this report, exposure is used most often in its general sense, meaning to be
3604 irradiated. When used as the specifically defined radiation quantity, exposure is a measure of
3605 the ionization produced in air by x or gamma radiation. The unit of exposure is coulomb per
3606 kilogram (C kg"1). The special unit for exposure is roentgen (R), where 1 R = 2.58 x 10"4 C
3607 kg"1.
3608 Exposure categories-
3609 Medical exposure - exposure incurred by patients for the purpose of medical or dental
3610 diagnosis or treatment; by carers and comforters associated with medical, dental, and
3611 veterinary procedures; and by volunteers in a program of biomedical research involving their
3612 exposure
3613 Occupational exposure - exposure of workers incurred in the course of their work
3614 Public exposure - exposure incurred by members of the public from sources in planned
3615 exposure situations, emergency exposure situations, and existing exposure situations,
3616 including incidental medical exposure, but excluding any occupational or prescribed medical
3617 exposure
80
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3618 Film/film radiograph - film is a thin, transparent sheet of polyester or similar material coated on
3619 one or both sides with an emulsion sensitive to radiation and light; a radiograph is a film or
3620 other record produced by the action of x-rays on a sensitized surface (NCRP 2003)
3621 Filtration - material in the useful beam that usually absorbs preferentially the less penetrating
3622 radiation (NCRP 2003)
3623 Fluoroscopy - the process of producing a real-time image using x-rays (NCRP 2003)
3624 Gamma ray - a photon emitted in the process of nuclear transition or radioactive decay
3625 Gray (Gy) - the special SI name for the unit of the quantities absorbed dose and air kerma. 1 Gy
3626 = 1 J kg"1 (see rad, rem, gray, and Si evert)
3627 Guidance level - optimal range of detector exposure index values that should be based on patient
3628 body habitus, anatomical view, clinical question, and other relevant factors
3629 Health physics - the field of science concerned with radiation physics and radiation biology and
3630 their application to radiation protection. Health physicists may specialize in nuclear power,
3631 environmental and waste management, laws and regulations, dosimetry, emergency response,
3632 medicine or a host of other sub-specialties where radiation is utilized. Of particular interest
3633 for this document is the medical health physics sub-specialty.
3634 Health physicist - a health professional, with education and specialist training in the concepts
3635 and techniques of applying physics in medical, environmental, or occupational settings, or
3636 competent to practice independently in one or more of the subfield specialties of medical
3637 physics or in health physics
3638 Health professional - an individual who has been formally recognized through appropriate
3639 national procedures to practice a profession related to health (e.g., medicine, dentistry,
3640 chiropractic, podiatry, nursing, veterinary medicine) (adapted from (IAEA201 la))
3641 Helical - spiral in form; a curve traced on a cylinder (or human body) by the rotation of a point
3642 crossing its right section at a constant oblique angle
3643 Image - representation of an object produced by machine-produced ionizing radiation
3644 Image receptor - a system for deriving a diagnostically usable image from the x-rays transmitted
3645 through the patient (NCRP 2003)
3646 Incidental exposure - exposure not associated with the primary purpose for which it was
3647 delivered
3648 Informed consent - voluntary agreement given by a person or a patients' responsible proxy (e.g.,
3649 a parent) for participation in a study, immunization program, treatment regimen, invasive
3650 procedure, etc., after being informed of the purpose, methods, procedures, benefits, and risks.
3651 The essential criteria of informed consent are that the subject has both knowledge and
3652 comprehension, that consent is freely given without duress or undue influence, and that the
3653 right of withdrawal at any time is clearly communicated to the patient. Other aspects of
3654 informed consent in the context of epidemiologic and biomedical research, and criteria to be
3655 met in obtaining it, are specified in International Guidelines for Ethical Review of
3656 Epidemiologic Studies (Chanaud 2008; Stedman 2006)(Geneva: CIOMS/WHO 1991) and
3657 International Ethical Guidelines for Biomedical Research Involving Human Subjects (Geneva:
3658 CIOMS/WHO 1993).
3659 Intensifying screen - a device consisting of fluorescent material, which is placed in contact with
3660 the film in a radiographic cassette. Radiation interacts with the fluorescent material, releasing
3661 light photons, (adapted from (NCRP 2003)
81
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3662 Interlock - device that automatically shuts off or reduces the radiation emission rate from an
3663 accelerator to acceptable levels (e.g., by the opening of a door into a radiation area). In
3664 certain applications, an interlock can be used to prevent entry into a treatment room.
3665 Intervention - any measure taken to alter the course of medical diagnosis whose purpose is to
3666 improve a health outcome
3667 Isocenter - the small point in space (or generally spherical or elliptical volume) where radiation
3668 beams emitted during the rotational swing of an x-ray tube gantry intersect
3669 Justification - the process of determining for a planned exposure situation whether a practice is,
3670 overall, beneficial, i.e. whether the expected benefits to individuals and to society from
3671 introducing or continuing the practice outweigh the harm (including radiation detriment)
3672 resulting from the practice (IAEA 2011 a)
3673 Kerma (kinetic energy released per unit mass, or kinetic energy released in matter) - the sum of
3674 the initial kinetic energies of all the charged particles liberated by uncharged particles (e.g., x-
3675 rays) in a material of mass 5m (IAEA 201 la). The unit for kerma is J kg-1, with the special
3676 name gray (Gy). Kerma can be quoted for any specified material at a point in free space or in
3677 an absorbing medium (e.g., air kerma).
3678 Kerma-area product (KAP, also called dose-area product or DAP) - the product of the air kerma
3679 and the area of the irradiated field and is measured in Gycm2, so it does not change with
3680 distance from the x-ray tube. A good measure of total energy delivered to the patient, and of
3681 stochastic risk. Not a good indicator of deterministic risk.
3682 Licensed independent practitioner - any individual permitted by law and by the organization to
3683 provide care and services, without direction or supervision, within the scope of the
3684 individual's license and consistent with individually granted clinical privileges (see Referring
3685 Medical Practitioner and Radiological Medical Practitioner)
3686 Mammography - the use of x-rays to produce a diagnostic image of the breast
3687 Medical exposure - exposure incurred by patients for the purposes of medical or dental diagnosis
3688 or treatment; by careres and comforters; and by volunteers subject to exposure as part of a
3689 program of biomedical research (IAEA 201 la)
3690 Medical health physics - the profession dedicated to the protection of healthcare providers,
3691 members of the public, and patients from unwarranted radiation exposure. Medical health
3692 physicists are knowledgeable in the principles of health physics and in the applications of
3693 radiation in medicine. While medical physics and medical health physics have a number of
3694 similarities and overlapping fields of study and interest, the emphasis of practice or day-to-
3695 day routines are different.
3696 Medical physics - a field of science concerned with applying physics to medical imaging and
3697 determining patient dose. The Medical Physicist's clinical practice focuses on methods to assure
3698 the safe and effective delivery of radiation to achieve a diagnostic or therapeutic result as
3699 prescribed in patient care.
3700 Medical physicist - a health professional, with education and specialist training in the concepts
3701 and techniques of applying physics in medicine, competent to practice independently in one or
3702 more of the subfield specialties of medical physics (IAEA2011a)
3703 Medical technologist - a health professional, with specialist education and training in medical
3704 radiation technology, competent to carry out radiological procedures, on delegation from the
3705 radiological medical practitioner, in one or more of the specialties of medical radiation
3706 technology (IAEA201 la)
82
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3707 Members of the public - all persons who are not already considered occupationally exposed by a
3708 source or practice under consideration. When being irradiated as a result of medical care,
3709 patients are a separate category.
3710 Occupational exposure - exposure to an individual that is incurred in the workplace as a result of
3711 situations that can reasonably be regarded as being the responsibility of management
3712 (exposures associated with medical diagnosis or treatment for the individual are excluded).
3713 (NCRP2003)
3714 Optically stimulated luminescent (OSL) dosimeter - a dosimeter containing a crystalline solid
3715 for measuring radiation dose, plus filters to help characterize the types of radiation
3716 encountered. When irradiated with intense light, OSL crystals that have been exposed to
3717 ionizing radiation give off light proportional to the energy they receive from the radiation
3718 (NCRP2003).
3719 Optimal dose - the minimum radiation dose required to be delivered by an x-ray imaging system
3720 to produce an image that is of adequate quality for the intended purpose. This requires that
3721 the x-ray generator and imaging equipment to be working appropriately, (see adequate image).
3 722 Optimization of protection - the process of determining what level of protection and safety
3723 would result in the magnitude of individual doses, the number of individuals (workers and
3724 members of the public) subject to exposure and the likelihood of exposure being "as low as
3725 reasonably achievable, economic and social factors being taken into account" (ALARA) (as
3726 required by the System of Radiological Protection). For medical exposures of patients, the
3727 optimization of protection and safety is the management of the radiation dose to the patient
3728 commensurate with the medical purpose. "Optimization of protection and safety" means that
3729 optimization of protection and safety has been applied and the result of that process has been
3730 implemented. (IAEA 2011 a)
3731 Personal protective equipment - specialized clothing or equipment (e.g., leaded or tungsten
3732 apron, gloves, thyroid collar, eyeglasses) worn by an employee to protect against a hazard.
3733 General work clothes not intended to serve as a protection against a hazard are not considered
3734 to be personal protective equipment.
3735 Phantom - as used in this report, a volume of tissue- or water-equivalent material used to
3736 simulate the absorption and scattering characteristics of the patient's body or portion thereof
3737 Picture archiving and communications system (PACS) - electronic system for the archival
3738 storage and transfer of information associated with x-ray images
3739 Pitch - in CT, table incrementation per x-ray tube rotation divided by the nominal x-ray beam
3740 width at isocenter
3741 Prescribe - the process of requesting or ordering an exam to be performed, or the process of
3742 determining how an exam should be done in order to optimize the choice of study and
3743 protocol, and optimize the radiation dose
3744 Protocol - selected parameters for image acquisition that defines the portion of the patient's
3745 anatomy to be imaged, whether and how contrast agents will be administered, the number and
3746 timing of imaging sequences, and acquisition technical parameters (pitch, collimation or beam
3747 width, kV, mA (constant or modulated and specifying the parameters determining the balance
3748 between image noise and patient dose), rotation time, physiologic gating, image quality
3749 factors, and reconstruction method
3750 Pulsed (as in pulsed fluoroscopy) - x-rays not produced continuously, but in rapid succession as
3751 pulses. Reduces dose by using a lower pulse rate (e.g., 15 or 7.5 pulses/sec) and in
3752 conjunction with digital image memory to provide a continuous video display
83
-------
3753 Qualified expert - an individual who, by virtue of certification by appropriate boards or societies,
3754 professional licenses or academic qualifications and experience, is duly recognized as having
3755 expertise in a relevant field of specialization, e.g. medical physics, radiation protection,
3756 occupational health, fire safety, quality assurance or any relevant engineering or safety
3757 specialty (IAEA 201 la)
3758 Qualified physicist - an individual who is competent to practice independently in the relevant
3759 medical subfield of medical physics or health physics. In general, a health physicist or
3760 medical physicist with appropriate training and experience regarding the medical use of x-rays
3761 is considered a qualified physicist. Ideally, persons should have certification from the
3762 American Board of Health Physics, the American Board of Medical Physics, the American
3763 Board of Radiology, or the American Board of Industrial Hygiene, to be considered a
3764 qualified expert in these respective fields. For the purposes of this document, the relevant
3765 subfield of medical physics is diagnostic radiological physics. Certification, continuing
3766 education, and experience are factors toward demonstrating that an individual is a qualified
3767 physicist. Individual federal agencies may develop their own criteria for determining when a
3768 physicist is a "Qualified Physicist" as defined in this document.
3769 Qualified medical physicist - an individual who is competent to practice independently in the
3770 relevant subfield of medical physics. For the purposes of this document, the relevant subfield
3771 is diagnostic radiological physics. Certification and continuing education and experience in
3772 the relevant subfield is one way to demonstrate that an individual is competent to practice in
3773 that subfield of medical physics and to be a qualified medical physicist.
3774 Quality assurance - the function of a management system that provides confidence that specified
3775 requirements will be fulfilled
3776 Rad - the special (traditional or historical) name for the unit of absorbed dose. 1 rad = 0.01 J kg"
3777 \ In the SI system of units, it is replaced by the special name gray (Gy). 1 Gy = 100 rad
3778 (NCRP 2000). (see rad, rem, gray, and Sievert)
3779 Radiation Safety Officer - the individual whose responsibility it is to ensure adequate protection
3780 of workers and the public from exposure to ionizing radiation
3781 Radiation weighting factor, WR - a number (as specified in the System for Radiological
3782 Protection) by which the absorbed dose in a tissue or organ is multiplied to reflect the relative
3783 biological effectiveness of the radiation in inducing stochastic effects at low doses, the result
3784 being the equivalent dose (IAEA 2011 a)
3785 Radiography - the production of images on film or other record by the action of x-rays
3786 transmitted through the patient (NCRP 2003)
3787 Radiological Medical Practitioner - a health professional with specialist education and training
3788 in the medical uses of radiation, who is competent to perform independently or to oversee
3789 procedures involving medical exposure in a given specialty (IAEA 201 la) (see licensed
3790 independent practitioner)
3791 Reference dose, patient entrance reference dose (or reference air kerma, reference dose,
3792 cumulative dose, cumulative air kerma, KA,R) - the dose at the patient entrance reference
3793 point. For C-arm fluoroscopic equipment, this is also known as the interventional reference
3794 point, and is located along the central ray of the x-ray beam, 15 cm back from the isocenter
3795 toward the x-ray tube. The isocenter is the central point about which the C-arm rotates.
3796 Reference dose is measured in Gy and is not the same as skin dose (IEC 2008).
84
-------
3797 Reference level - a level used in medical imaging to indicate whether, in routine conditions, the
3798 dose to the patient in a specified radiological procedure is unusually high or low for that
3799 procedure
3800 Referring Medical Practitioner - a health professional who, in accordance with national
3801 requirements, may refer individuals to a radiological medical practitioner for medical
3802 exposure (IAEA 201 la) (see licensed independent practitioner)
3803 Registry - central national repository for patient radiation dose and equipment parameter data
3804 Rem - the special (traditional or historical) name for the unit of dose equivalent numerically
3805 equal to the absorbed dose (D) in rad, modified by a quality factor (Q). 1 rem = 0.01 J kg"1. In
3806 the SI system of units, it is replaced by the special name si evert (Sv), which is numerically
3807 equal to the absorbed dose (D) in gray modified by a radiation weighting factor (COR). 1 Sv =
3808 100 rem (NCRP 2003). (see rad, rem, gray, and Sievert)
3809 Resolution - in the context of an imaging system, the output of which is finally viewed by the
3810 eye, it refers to the smallest size or highest spatial frequency of an obj ect of given contrast that
3811 is just perceptible. The resolution actually achieved with imaging lower contrast obj ects is
3812 normally much less, and depends upon many variables such as subject contrast levels and
3813 noise of the overall imaging system (NCRP 2003).
3814 Risk - the probability or quantifiable likelihood that a detriment to health will occur as a result of
3815 performing or not performing a medical procedure
3816 Roentgen - the special name for exposure, which is a specific quantity of ionization (charge)
3817 produced by the absorption of x- or gamma-radiation energy in a specified mass of air under
3818 standard conditions. 1 R = 2.58 x 10"4 coulombs per kilogram (C kg'1) (NCRP 2003).
3819 Screening - the evaluation of an asymptomatic person in a population to detect a disease process
3820 not known to exi st at the time of evaluation
3821 Sievert (Sv) - the special SI name for the quantities equivalent dose or effective dose.
3822 Equivalent dose is the radiation protection quantity used for setting limits that help ensure that
3823 deterministic effects (e.g. damage to a particular tissue) are kept within acceptable levels. The
3824 SI unit of equivalent dose is the J kg"1, and is abbreviated HT. It is numerically equal to a
3825 radiation weighting factor (COR) [or quality factor (Q)] multiplied by the absorbed dose in
3826 tissue T (DT,R). 1 Sv = 100 rad (NCRP 2003). The formula is:
3 827 HT = ZR roR DT,R or ZR QR DT;R
3828 where
3 829 COR = radiation weighting factor,
3830 DT,R = absorbed dose to tissue T from radiation type R, and
3831 QR= quality factor.
3832
3833 Effective dose is the radiation protection quantity used for setting limits that help ensure that
3834 stochastic effects (i.e., cancer and genetic effects) are kept within acceptable levels. The SI
3 83 5 unit of effective dose is the J kg"1, and is abbreviated HE. It is numerically equal to a radiation
3836 weighting factor (COR) multiplied by a tissue weighting factor (COT) and the absorbed dose from
3837 that radiation in tissue T (DT,R) in gray. Identically, it is the equivalent dose multiplied by a
3838 tissue weighting factor. 1 Sv = 100 rem (NCRP 2003). The formula is:
3839 HE = ZT COT ZR roR DT,R = ZT HT COT
3840 where
3841 HE = the effective dose (or effective dose equivalent) to the entire individual,
3842 COT = the tissue weighting factor in tissue T,
85
-------
3843 HT = the equivalent dose (or dose equivalent),
3 844 COR = the radiation weighting factor, and
3845 DT,R = the absorbed dose to tissue T from radiation type R.
3846 (see rad, rem, gray, and Si evert)
3 847 Signal to noise ratio - the ratio of input signal to background interference. The greater the ratio,
3 848 the clearer the image (NCRP 2003).
3849 Skin dose - radiation dose to the dermis, measured for example as entrance skin dose or peak
3850 skin dose
3851 Slice - a 2-dimensional reconstructed cross-sectional image depicting a patient's anatomy
3852 produced using x-rays, MRI, ultrasound, or other non-invasive means
3853 Step wedge - a device with various thicknesses of aluminum used to verify the consistency of
3854 the x-ray and film processing systems. Typically each step of the stepwedge is about 1 mm
3855 thick and about 3 to 4 mm wide with at least 6 steps. The device is placed on a film cassette
3856 and exposed under the exact same exposure parameters and geometry set up. The film is then
3857 developed and the steps are visually compared to the reference film identically exposed and
3858 processed in fresh solutions under ideal conditions. A reproducible change of one step or
3859 more in density should signal the need for corrective action.
3860 Stochastic effects - effects, the probability of which, rather than their severity, is a function of
3861 radiation dose, implying the absence of a threshold. More generally, stochastic means random
3862 in nature (NCRP 2003).
3863 Supervision, general - means the procedure is furnished under the supervising individual's
3864 overall direction and control, but the supervising individual's presence is not required during
3865 the performance of the procedure. Under general supervision, the training of the personnel
3866 who actually perform the task and the maintenance of the necessary equipment and supplies
3867 are the continuing responsibility of the supervising individual (adapted from (DHHS 2012a)
3868 Supervision, direct - means the supervising individual must be present in the local area (for
3869 physicians, in the office suite) and immediately available to furnish assistance and direction
3870 throughout the performance of the procedure. It does not mean that the supervising individual
3871 must be present in the room when the task is performed (adapted from (DHHS 2012a)).
3872 Supervision, personal - means a supervising individual must be in attendance in the room during
3 873 the performance of the task (adapted from (DHHS 2012a))
3874 Technique factor - operator selectable parameter affecting the x-ray beam (e.g., kV, mA, time)
3875 Tissue weighting factor, wT - multiplier of the equivalent dose to an organ or tissue, as given by
3876 the System for Radiological Protection, used for radiation protection purposes to account for
3877 the different sensitivities of different organs and tissues to the induction of stochastic effects
3878 of radiation (IAEA 201 la)
3879 Tomography - a special technique to show in detail images of structures lying in a
3880 predetermined plane of tissue, while blurring or eliminating detail in images of structures in
3881 other planes (NCRP 2003)
3882 Total effective dose equivalent (TEDE) - the sum of the deep-dose equivalent (for external
3883 exposures) and the committed effective dose equivalent (for internal exposures)
3884 Universal Protocol - A Joint Commission process developed to address wrong site, wrong
3885 procedure, and wrong person surgeries and other procedures. The three principal components
3886 of the Universal Protocol include a pre-procedure verification, site marking, and a timeout
3887 (The Joint Commission 2012a; The Joint Commission 2012b)
86
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3888 Worker - any person who works, whether full time, part time or temporarily, for an employer
3889 and who has recognized rights and duties in relation to occupational radiation protection
3890 (IAEA 2011 a)
87
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3891
3892
3893
3894
3895
3896
3897
3898
3899
3900
3901
3902
3903
3904
3905
3906
3907
3908
3909
3910
3911
3912
APPENDIX A - NIH INFORMED CONSENT TEMPLATES
The guidance in this appendix is suitable for research involving diagnostic and interventional x-
ray procedures. It applies to radiation use indicated for research involving human subjects.
Examples might include evaluating new mammography protocol using lower kVp as
recommended by ICRP, virtual colonoscopy, and national lung screening trials. It excludes
radiation oncology research, in which radiation doses to subjects may be much higher. A
discussion of human subjects research ethics, patient benefit:risk considerations, and the role of
Institutional Review Boards is beyond the scope of this document, but is an essential process
prior to the conduct of research involving human subjects.
The risk from research protocols involving radiation use indicated for research, as described
above, can be categorized into groups. A useful approach is to group risk as minimal, minor to
intermediate, or moderate. The templates on the following pages are adapted from those used by
the NIH in 2012 (less than 1 mSv (100 mrem) "minimal" and 1 -50 mSv (100 mrem - 5 rem)
"minor to intermediate"). Doses above 50 mSv (5 rem) may be considered to range from
moderate to substantial. The specific ranges and text may be adjusted as required by the specific
IRB (NIH 2001; NIH 2008a; NIH 2008b; NIH 2010). Another approach to selecting the dose
ranges and descriptors for these templates is shown below.
Classification schemes for use of E as a qualitative indicator of stochastic risk for diagnostic and
interventional x-ray procedures
Range of E
(mSv)
<0.1
0.1-1
1-10
10-100
>100
Radiation Risk Descriptor
ICRP
Trivial
Minor
Intermediate
Moderate
Martin (2007)
Negligible
Minimal
Very low
Low
NCRP
Negligible
Minimal
Minor
Low
Acceptable (in
context of the
expected benefit)
Expected Minimum
Individual or Societal Benefit
Describable
Minor
Moderate
Substantial
Justifiable expectation of very
substantial individual benefit
Adapted from: (ICRP 1991b; Martin 2007)
3913
3914
3915
A-l
-------
3916 MINIMAL RISK
3917 Adapted from NIH TEMPLATE A (Total effective dose less than or equal to 1 mSv (100 mrem))
3918
3919 This research study involves exposure to radiation from (insert type of procedure or procedures).
3920 Please note that this radiation exposure is not necessary for your medical care and is for research
3921 purposes only.
3922
3923 The total amount of radiation you will receive in this study is from (insert maximum number) of
3924 (insert description of type of x-ray procedure). The Radiation Safety Committee has reviewed
3925 the use of radiation in this research study and has approved this use as involving minimal risk
3926 and necessary to obtain the research information desired.
3927
3928 You will receive a total of (XX) mSv or (YY) rem to your (insert highest-dosed organ, typically
3929 skin) from participating in this study. All other parts of your body will receive smaller amounts
3930 of radiation. Although each organ will receive a different dose, the amount of radiation exposure
3931 you will receive from this study is equal to a uniform whole-body exposure of less than (insert
3932 total effective dose value). This calculated value is known as the "effective dose" and is used to
3933 relate the dose received by each organ to a single value.
3934
3935 For comparison, the average person in the United States receives a radiation dose of 3 mSv (300
3936 mrem) per year from natural background sources, such as from the sun, outer space, and from
3937 radioactivity found naturally in the earth's air and soil. The dose that you will receive from
3938 participation in this research study is about the same amount you would normally receive in
3939 (insert number) months from these natural sources.
3940
3941 While there is no direct evidence that the small radiation dose received from participating
3942 in this study is harmful, there is indirect evidence it may not be completely safe. There
3943 may be an extremely small increase in the risk of cancer.
3944
A-2
-------
3945 MINOR TO INTERMEDIATE RISK
3946 Adapted from Nffl TEMPLATE B (7 mSv < Total effective dose = < 50 mSv) or (100 mrem <
3947 Total effective dose = < 5 rem)
3948
3949 This research study involves exposure to radiation from (insert type of procedure or procedures}.
3950 Please note that this radiation exposure is not necessary for your medical care and is for research
3951 purposes only.
3952
3953 The total amount of radiation you will receive in this study is from (insert maximum number}
3954 (scans or repetitions) of (insert description of type of x-ray procedure). The Radiation Safety
3955 Committee has reviewed the use of radiation in this research study and has approved this use as
3956 involving low risk (more than minimal but less than moderate) and necessary to obtain the
3957 research information desired.
3958
3959 Although each organ will receive a different dose, the amount of radiation exposure you will
3960 receive from this study is equal to a uniform whole-body exposure of less than (insert total
3961 effective dose value). This calculated value is known as the "effective dose" and is used to relate
3962 the dose received by each organ to a single value. The amount of radiation you will receive in
3963 this study is less than the annual radiation dose of 50 mSv per year (5 rem per year) permitted for
3964 someone who works with radiation on a daily basis.
3965
3966 For comparison, the average person in the United States receives a radiation dose of 3 mSv (300
3967 mrem) per year from natural background sources, such as from the sun, outer space, and from
3968 radioactivity found naturally in the earth's air and soil. The dose that you will receive from
3969 participation in this research study is about the same amount you would normally receive in
3970 (insert number) months from these natural sources.
3971
3972 The effects of radiation exposure on humans have been studied for over 60 years. In fact, these
3973 studies are the most extensive ever done of any potentially harmful agent that could affect
3974 humans. In all these studies, no harmful effect to humans has been observed from the levels of
3975 radiation you will receive by taking part in this research study. However, scientists disagree on
3976 whether radiation doses at these levels are harmful. Even though no effects have been observed,
3977 some scientists believe that radiation can be harmful at any dose - even low doses such as those
3978 received during this research.
3979
3980 While there is no direct evidence that the radiation dose received from participating in this
3981 study is harmful, there is indirect evidence it may not be completely safe. There may be a
3982 small increase in the risk of cancer.
3983
3984 (INCLUSION OF THIS IS OPTIONAL) Some people may be concerned that
3985 radiation exposure may have an effect on fertility or cause harm to future children. The radiation
3986 dose you will receive in this research study is well below the level that affects fertility. In
3987 addition, radiation has never been shown to cause harm to the future children of individuals who
3988 have been exposed to radiation. Harm to future generations has been found only in experiments
3989 on animals that have received radiation doses much higher than the amount you will receive in
3990 this study.
A-3
-------
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