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 ------- DRAFT PROPOSAL 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 ------- DRAFT PROPOSAL 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. II ------- DRAFT PROPOSAL 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. 123 124 125 126 127 128 129 III ------- DRAFT PROPOSAL 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 ------- 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 V ------- DRAFT PROPOSAL 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 ------- DRAFT PROPOSAL 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 ------- DRAFT PROPOSAL 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 ------- 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 34 287 288 289 IX ------- 290 291 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319| 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 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 343 344 345 346 347 348 349 350 351 352 353 354 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 ------- 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 ------- 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. ------- DRAFT PROPOSAL 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 ------- DRAFT PROPOSAL 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 ------- DRAFT PROPOSAL 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 ------- 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 ------- 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 ------- 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 ------- 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 ------- 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 ------- 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 ------- 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 ------- 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 ------- 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 ------- 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 ------- 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 ------- 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 ------- 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 ------- 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 ------- 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 ------- 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 ------- 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 ------- 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 ------- 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 ------- 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 ------- 3991 3992 REFERENCES 3993 3994 3995 AAPM. 1998. AAPM Report No. 58: Managing the use of Fluoroscopy in Medical Institutions. 3996 American Association of Physicists in Medicine. 3997 AAPM. 2005. AAPM TG18 On-line Report No. 03: Assessment of Display Performance for 3998 Medical Imaging Systems. College Park, MD: American Association of Physicists in 3999 Medicine. 4000 AAPM. 2006a. AAPM Report No. 93: Acceptance Testing and Quality Control of 4001 Photostimulable Storage Phosphor Imaging Systems. American Association of Physicists 4002 in Medicina. 4003 AAPM. 2006b. 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