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 

2012 

1 
I 

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 
II 

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 González 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 González 

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-year80 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. 
III 

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 
IV 

130 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 tools. 

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.
V 

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

199 Radiological Medical Practitioners 18
VI 

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

233 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

240 Personnel 49

241 Procedures 49
VII 

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

277 APPENDIX A – NIH INFORMED CONSENT TEMPLATES A-1

278 MINIMAL RISK A-2
VIII 

279 MINOR TO INTERMEDIATE RISK A-3

280 REFERENCES REF-1

281 

282 
IX 

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 
X 

290 INTERAGENCY WORKING GROUP ON MEDICAL RADIATION 

291 292 

293 

294 Department of Health and Human Services 

295 L. Samuel Keith, MS, CHP, CO-CHAIR 

296 John L. McCrohan, MS (retired) 

297 Donald L. Miller, MD, FSIR FACR 

298 Petro Shandruk (retired) 

299 

300 Department of the Air Force 

301 Cindy L. Elmore, Ph.D., DABR 

302 LTC Scott Nemmers, BSC 

303 

304 Department of the Army 

305 COL Mark W. Bower, CHP, Ph.D. 

306 COL Erik H. Torring, DVM, MPH 

307 

308 Department of Labor, 

309 Occupational Safety and Health Administration

310 Doreen G. Hill, MPH, Ph.D. 

311 

312 Department of the Navy 

313 CAPT Stephen T. Sears, MC, CO-CHAIR 

314 CAPT Michael A. Ferguson, MC 

315 CDR Douglas W. Fletcher, MSC 

316 CDR Chad A. Mitchell, MSC 

317 

318 Department of Veterans Affairs 

319 Ronald C. Hamdy, MD, FRCP, FACP

320 Edwin M. Leidholdt, Jr., Ph.D. 

321 Eleonore D. Paunovich, DDS, MS 

322 

323 

324 

325 

326 

327 

328 

329 

330 

331 

332 

333 

334 

335 

336 

337 

338 

339 

340 

341 

342 Environmental Protection Agency 

343 Michael A. Boyd, MSPH 

344 

345 Commonwealth of Pennsylvania 

346 John P. Winston 

347 

348 Expert Consultants/Other Contributors 

349 Kimberly Applegate, MD, MS, FACR 

350 Charles E. Chambers, MD, FACC FSCAI 

351 Steven Don, MD 

352 Marilyn Goske, MD 

353 Fred A. Mettler, MD, MPH, FACR 

354 Terrence J. O’Neil, MD, FACP 

355 S. Jeff Shepard, MS 

356 Dana M. Sullivan, RT(R)(M) , DVA 

357 

358 

359 

360 

361 Acknowledgements 

362 

363 Environmental Protection Agency 

364 Helen Burnett (retired) 

365 Jessica Wieder 

366 

367 Department of Health and Human Services 

368 J. Nadine Gracia, MD 

369 Sandra Howard 

370 
1 

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 image413 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 
2 

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. 
3 

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 x476 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 benefit:risk 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 
4 

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 (ICRP 2007a). 

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 
5 

546 The principle of application 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 breast552 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:cite NEMA 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 non563 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 
6 

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 staff or 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 
7 

638 woman” per 10CFR20.1003 (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 
8 

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 benefit:risk 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 
9 

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. 

738 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 QA 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 
10 

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 staff or 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 whole812 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 
11 

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 0.35 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. 
12 

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 benefit:risk 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 
13 

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 medically919 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 
14 

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 (NIH 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 
15 

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 2011b). 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 2011b). 

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” 
16 

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 benefit:risk 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 benefit:risk 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 radiographic 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 benefit:risk 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 
17 

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 life1125 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 
18 

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-credentialed 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 
19 

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 benefit:risk 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 
20 

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 

1233 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 (FDA 2012c). 

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 
21 

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). 
22 

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 
23 

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, 
24 

1379 rotation speed, pitch, selection of a mode in which mA is modulated during the scan (if 

1380 available), and degree of noise reduction (if available). Technique factors may be programmed 

1381 into the imaging device, or they may be manually selected. If they are programmed in, 

1382 programming should be consistent across all similar devices at a facility. Technique factors 

1383 should be chosen that produce a clinically-adequate image at the least dose to the patient, not an 

1384 ideal image. Whenever possible, technique factors should be adjusted to the thickness of the 

1385 patient. 

1386 

1387 If the review of technique factors used clinically or the comparison of dose indices indicates that 

1388 an optimum balance has not been achieved between patient dose and image quality or that 

1389 patient doses exceed national standards, the technique factors, whether posted in a chart or 

1390 programmed into the imaging device, and/or selection of image receptor, should be modified as 

1391 necessary. 

1392 

1393 TESTING BY A QUALIFIED PHYSICIST 

1394 

1395 It is strongly recommended that the technical quality assurance program includes testing by a 

1396 qualified physicist of all imaging equipment producing x-rays. The equipment should be tested 

1397 after installation but before first clinical use, annually thereafter, and after each repair or 

1398 modification that may affect patient dose or image quality. Testing after repair or modification 

1399 should be performed before clinical use of the equipment. The testing, including a summary of 

1400 methods, instruments used, measurements and deficiencies identified, should be documented in a 

1401 written report signed by the qualified physicist. The testing should include the items in Table 1 

1402 below: 

1403 

Table 1. Testing Frequency of Imaging Equipment that Produces X-Rays 

TASK INITIAL AFTER 

MODIFICATION 

OR REPAIR (a) 

ANNUAL 

Measure radiation output parameters, including 

beam intensity and beam quality 

X X X 

Test modes of operation used clinically, such as 

automatic control systems (e.g., automatic 

exposure controls of radiographic systems, 

automatic exposure rate controls of fluoroscopy 

systems.) 

X X X 

Assess image quality X X X 

Determine Detector Exposure Index Accuracy 

(b) 

X X X 

Evaluate the accuracy of patient dose or dose 

rate indicators 

X X X 

Assess the typical patient dose delivered for 

various examinations for comparison to national 

reference levels 

X X X 

Perform an acceptance test X X 
25 

Table 1. Testing Frequency of Imaging Equipment that Produces X-Rays 

TASK INITIAL AFTER 

MODIFICATION 

OR REPAIR (a) 

ANNUAL 

Review the overall technical quality control 

program 

 X 

Perform a periodic review of all CT protocols (c) 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 TG116 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 The qualified physicist may be assisted by other properly trained persons in obtaining test data 

1406 for performance monitoring. These persons should be trained by the qualified physicist in the 

1407 techniques for performing the tests, the function and limitations of the imaging equipment and 

1408 test instruments, the reasons for the tests, and the importance of the test results. The qualified 

1409 physicist should be present at the facility for the initial and annual testing and should promptly 

1410 review, interpret, and approve all data measurements and test results. 

1411 

1412 EQUIPMENT FAILURE 

1413 

1414 When x-ray imaging equipment fails to meet the performance specifications, the equipment 

1415 should be promptly adjusted or repaired to correct the deficiency or should be removed from 

1416 clinical use. A written or electronic record should be kept of the correction of such deficiencies 

1417 in accordance with the organization’s record keeping policy. The record should include the date 

1418 of correction and the action taken to correct the deficiency. 

1419 

1420 DEFICIENCY CORRECTION VERIFICATION 

1421 

1422 After correction of deficiencies that affect patient dose or image quality, the equipment should be 

1423 tested promptly, by or under the supervision of a qualified physicist, to verify that the deficiency 

1424 was corrected and that the correction did not cause other deficiencies. 

1425 

1426 DOSIMETRY 

1427 

1428 Patient dose indices, measured at clinically-used technique factors by or under the supervision of 

1429 a qualified physicist, should be available for review. For radiography, entrance skin exposures 

1430 for common projections should be listed for a patient of typical thickness. For fluoroscopy 

1431 systems that have appropriate dosimetry measurement capabilities (e.g., air kerma or dose area 

1432 product), the accuracy should be measured and recorded. For fluoroscopy systems that do not 

1433 have dosimetry indicators, the typical and maximal entrance skin exposure estimates should be 

1434 measured and recorded for each fluoroscopic mode of operation for small, average, and large 

1435 patient thicknesses. 
26 

1436 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 (Vañó 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 (Vañó 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 

approximately the 75th 1468 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 
27 

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 (Vañó 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 (Balter 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 2010a). 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 levels in the U.S. (ACR 2008b). 

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 (Balter 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 (Balter 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 (Balter et al. 2008; IAEA 2009). 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 
28 

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 
29 

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 
30 

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 radiographic 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 film1616 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 
31 

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. 
32 

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 
33 

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. A board certified radiologist is preferred. Periodic review of the radiographic 

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. 
34 

1763 Continuation of a standardized examination procedure should be predicated on satisfying the 

1764 following criteria: 

1765 

1766 1. the efficacy of the examination is sufficiently high to assure that the diagnosis could not 

1767 have been made with less risk by other non-radiological means or a smaller number of 

1768 views, 

1769 2. consideration of previous similar examinations performed with multiple views established 

1770 that in a significant number of the cases all views were necessary for the diagnoses 

1771 rendered, and 

1772 3. the yield or outcome of the examinations offsets the radiation exposure delivered. 

1773 

1774 A periodic review should be performed at least annually by experts designated by departmental 

1775 leadership, and with the input of referring physicians. These reviews should consider applicable 

1776 regulations as well as the consensus and advice of professional societies concerning the efficacy 

1777 of radiologic examinations. 

1778 

1779 Other quality assurance measures are listed in Table 2 below. The specifics of these measures 

1780 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 Frequency Methodology 

Physicist testing See Table 1 See section on Technical Quality Assurance in Medical 

Imaging with X-Rays. 

Processor Monitoring Daily Clean crossover racks and perform sensitometry test. 

Darkroom Cleaning Weekly Check for dust, clutter, etc. 

Processor Preventive 

Maintenance 

Monthly Perform deep cleaning and evaluate darkroom chemicals as 

recommended by the manufacturer. 

Screen Cleaning Monthly Clean all screens in inventory according to manufacturer’s 

recommendations 

Repeat Analysis Quarterly 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. 

Darkroom Fog Annually 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. 

Film-Screen Contact Test Annually Follow film-screen contact test tool instructions. 

Review Local Radiation 

Protection and Quality 

Control Operating 

Instructions 

Annually Revise as needed. 
35 

1781 

Computed Radiography 

Task Frequency Methodology 

Physicist testing See Table 1 See section on Technical Quality Assurance in Medical 

Imaging with X-Rays. 

Image Plate Erasure Weekly, or 

daily if 

unsure of 

status 

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). 

Quality Control Phantom 

Image Acquisition 

Monthly Follow manufacturer’s recommendations. 

Transmit Phantom Image 

to Interpreting Medical 

Treatment Facility (MTF) 

Monthly For Teleradiology Sites Only: After acquisition of QC 

image, transmit to interpreting MTF for verification of 

image quality. 

Operator Console At least 

Monthly 

View and evaluate QC pattern (AAPM 2005), clean 

monitors. 

Repeat Analysis Quarterly 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. 

Dose Monitoring Quarterly Review patient dose indices according to manufacturer’s 

recommendations. 

Detector Exposure Index 

Monitoring 

Quarterly Review exposure indicators according to AAPM TG116 

methodology (AAPM 2009) and compare with guidance 

levels. One source for appropriate guidance levels may be 

the manufacturer. 

Image Plate Inspection 

and Cleaning 

Quarterly Follow manufacturer’s recommendations for proper 

cleaning technique using approved cleaning solution and 

proper safety precautions. 

Review Local Radiation 

Protection and Quality 

Control Operating 

Instructions 

Annually Revise as needed. 

1782 

Direct Digital 

Radiography 

 

Task Frequency Methodology 

Physicist testing See Table 1 See section on Technical Quality Assurance in Medical 

Imaging with X-Rays. 

Quality Control Phantom 

Image Acquisition

Weekly Follow manufacturer’s recommendations. 

Operator Console At least 

Monthly 

View and evaluate QC pattern (AAPM 2005), clean 

monitors. 
36 

Direct Digital 

Radiography 

 

Task Frequency Methodology 

Transmit Phantom Image 

to Interpreting MTF 

Monthly For Teleradiology Sites Only: After acquisition of QC 

image, transmit to interpreting MTF for verification of 

image quality. 

Repeat Analysis Quarterly Track and trend the repeat/reject rate and ensure it is less 

than or equal to 7% (NCRP 1988). 

Dose Monitoring Quarterly Review patient dose indices according to manufacturer’s 

recommendations. 

Detector Exposure Index 

Monitoring 

Quarterly Review exposure indicators according to AAPM TG116 

methodology (AAPM 2009) and compare with guidance 

levels. One source for appropriate guidance levels may be 

the manufacturer. 

Review Local Radiation 

Protection and Quality 

Control Operating 

Instructions 

Annually Revise as needed. 

1783 

Interpretation and QC 

Display Monitors 

 

Task Frequency Methodology 

User task: Visual 

assessment using QC test 

pattern

Daily AAPM TG-18 Online Report 3, table 8a or equivalent 

(AAPM 2005) 

Physicist, technologist 

tasks: Display system 

performance 

Monthly/ 

Quarterly AAPM TG-18 Online Report 3, table 8b or equivalent 

(AAPM 2005) 

Physicist tasks: display 

system calibration 

verification 

Initially 

and 

Annually 

AAPM TG-18 Online Report 3, table 8c, or equivalent

(AAPM 2005) 

Monitor cleaning Monthly 

and as 

needed 

Clean monitors with cleaner approved by manufacturer 

1784 

Other External 

Equipment 

 

Task Frequency Methodology 

Printer quality control See 

methodology

Follow manufacturer’s recommendations 

Digitizer quality control See 

methodology

Follow manufacturer’s recommendations 

1785 

1786 

1787 
37 

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 

1800 1. require testing of the fluoroscopic equipment by or under the direction of a qualified 

1801 physicist, 

1802 2. require training and credentialing of persons operating or directing the operation of 

1803 fluoroscopic equipment, 

1804 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 (ACR 2008c). 

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 

point exceeding 3 Gy or a kerma-area product (KAP) exceeding 300 Gy-cm2

1825 . 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 
38 

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 fluoroscopically1856 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 subject which 

1863 can be used for guidance (Chambers et al. 2011; Miller et al. 2010a; NCRP 2010; Stecker et al. 

1864 2009; Steele et al. 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 (Balter 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 
39 

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 (FDA 2012d; FDA 2012f). 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 (IEC 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 

and the area of the irradiated field and is measured in Gy·cm2

1892 . 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 ((IHE 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 
40 

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 x1960 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 
41 

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-on1992 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 
42 

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 kerma2061 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 
43 

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; Balter 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 (Balter 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 (FDA 2012b). 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 (Balter and Miller 2007; 
44 

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 

10th and 75th 2140 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 

the local median (50th 2148 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 

the 75th 2151 percentile of the guidance data) at the same time that there are an excessive number of 

cases with a radiation dose greater than the 95th 2152 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 
45 

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 (Balter 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 

The local median can be compared with the 10th, 50th (median) and 75th 2182 percentiles of the 

guidance data. A median value below the 10th 2183 percentile of the guidance data may indicate 

incomplete procedures. A median value between the 50th and 75th 2184 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 

is warranted if the local median exceeds the 75th 2187 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 
46 

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 staff or 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 
47 

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, projectional 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 fluoroscopically2270 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 et al. 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 
48 

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 
49 

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 
50 

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: 
51 

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 (ICRP 2012). 

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 (CTDIVOL), 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 
52 

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 
53 

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 appendicular 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 
54 

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 
55 

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 appendicular 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 

2638 the absorptiometry equipment they are operating, including performance of all manufacturer2639 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 Examination. 

2652 
56 

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: 
57 

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 
58 

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 

2735 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 lead2748 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 
59 

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 projection-angle of 

the panoramic x-ray beam of +4o

 to +7 o 2804 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 
60 

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 x2819 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 
61 

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 radiographic 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 

location, also known as the safe quadrant, is at an angle between 90 and 135o2885 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 
62 

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 
63 

2950 protection guidelines recommended for conventional dental imaging should be implemented for 

2951 CBCT. 

2952 
64 

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, battery2996 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 
65 

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. A typical 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 

3021 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 
66 

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 radiographic 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. 
67 

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 lead3107 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. 
68 

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 review). 

3176 
69 

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 IHE. 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 
70 

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 
71 

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 

3241 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. 
72 

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 dose3313 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. 
73 

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 
74 

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 non3370 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 
A-75 

3383 ACRONYMS AND ABBREVIATIONS 

3384 

3385 AAPM American Association of Physicists in Medicine 

3386 ACC American College of Cardiology 

3387 ACCF American College of Cardiology Foundation 

3388 ACGME Accreditation Council for Graduate Medical Education 

3389 ACR American College of Radiology 

3390 ACS American Cancer Society 

3391 ADA American Dental Association 

3392 AEC automatic exposure control 

3393 AHA American Heart Association 

3394 ALARA as low as reasonably achievable 

3395 AMA American Medical Association 

3396 ANSI American National Standards Institute 

3397 AOA American Osteopathic Association 

3398 AOBR American Osteopathic Board of Radiology 

3399 ARRT American Registry of Radiologic Technologists

3400 ATSDR Agency for Toxic Substances and Disease Registry 

3401 BEIR Biological Effects of Ionizing Radiation 

3402 BID beam indicating device 

3403 BMD bone mineral density 

3404 CBCT cone beam computed tomography (cone beam CT) 

3405 CFR Code of Federal Regulations 

3406 CIRSE Cardiovascular and Interventional Radiology Society of Europe 

3407 cm centimeter 

3408 CNMT Certified Nuclear Medicine Technologist 

3409 CR computed radiography 

3410 CRCPD Conference of Radiological Control Program Directors 

3411 CT computed tomography 

3412 CTDI computed tomography dose index 

CTDIvol 3413 volumetric CTDI 

DAP dose area product (units are Gy-cm2

3414 ) 

3415 DC direct current 

3416 DDM Doctor of Dental Medicine 

3417 DDR Direct digital radiography 

3418 DDS Doctor of Dental Surgery 

3419 DEXA see DXA 

3420 DHHS Department of Health and Human Services 

3421 DLP dose length product 

3422 DoD Department of Defense 

3423 DR digital radiography 

3424 DRT Diagnostic Radiologic Technologist 

3425 DXA dual-energy x-ray absorptiometry (formerly DEXA) 

3426 EHR Electronic Health Record 

3427 EPA Environmental Protection Agency 

3428 ESE entrance skin exposure 
 76 

3429 ESEG entrance skin exposure guide 

3430 FDA Food and Drug Administration 

3431 FGI Fluoroscopically-guided interventional 

3432 FGR Federal Guidance Report 

3433 FOV field of view 

3434 GI gastrointestinal 

3435 GSD genetically significant dose 

3436 Gy gray (radiation dose, equal to 100 rem). Subunit is mGy (milligray) 

3437 HRS Heart Rhythm Society 

3438 ICRP International Commission on Radiological Protection 

3439 IEC International Electrotechnical Commission 

3440 IRB Institutional Review Board 

3441 ISCD International Society for Clinical Densitometry 

3442 ISCORS Interagency Steering Committee on Radiation Standards 

3443 KAP kerma area product 

3444 kerma kinetic energy released in matter (type of radiation measurement in air) 

3445 kV kilovolts 

3446 kVp kilovolts potential (or kilovolts peak) 

3447 mA milliampere 

3448 mammo mammography 

3449 mAs milliampere-second 

3450 MDCT multi-row detector computed tomography (multi-detector CT) 

3451 MQSA Mammography Quality Standards Act 

3452 mrem millirem 

3453 mSv millisievert 

3454 NCI National Cancer Institute 

3455 NCRP National Council on Radiation Protection and Measurements 

3456 NEXT Nationwide Evaluation of X-ray Trends 

3457 NIH National Institutes of Health 

3458 OSHA Occupational Safety and Health Administration

3459 OSL optically stimulated luminescence 

3460 PACS picture archiving and communication system 

3461 PET positron emission tomography 

3462 PSD position-sensitive x-ray detection 

3463 PSP photostimulable phosphor 

3464 RCIS Registered Cardiovascular Invasive Specialists 

3465 rem Traditional radiation unit for equivalent dose (product of absorbed dose [rad] and 

3466 radiation weighting factor). Subunit is mrem (millirem) or μrem (microrem) 

3467 RSO Radiation Safety Officer 

3468 RT(N) Radiological Technologist Nuclear qualification 

3469 SCAI Society for Cardiac Angiography and Intervention 

3470 SPECT single particle emission computed tomography 

3471 SIR Society of Interventional Radiology 

3472 SSD source-to-skin distance 

3473 Sv sievert (SI radiation unit for equivalent dose or effective dose). Subunit is mSv 

3474 (millisievert) or μSv (microsievert) 
 77 

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 
 78 

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 injection 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 beam with the image receptor 

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 Benefit:risk 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 benefit:risk ratio involves balancing the benefit:risk 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 phosphor3521 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) 
 79 

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 (NCRP 2000) 

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 cone3531 shape x-ray beam (instead of fan-shaped) that rotates around the patient to generate a high3532 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 

CTDIvol 3536 – a radiation dose parameter derived from the CTDIw (weighted or average CTDI given 

3537 across the field of view). The formula is: 

CTDIvol 3538 = N·T·CTDIw / I, 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 

3547 rather than film projection 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 x3559 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 

kerma and the area of the irradiated field and is measured in Gy·cm23562 , so it does not 

3563 change with distance from the x-ray tube. A good measure of total energy delivered to 

3564 the patient, and of stochastic risk. Not a good indicator of deterministic risk 

3565 Dose alert value - a value of CTDIvol (in units of mGy) or of DLP (in units of mGy·cm) 

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) 
 80 

3572 Dose equivalent – the product of the absorbed dose at a point in the tissue or organ and 

3573 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 = 

CTDIvol 3576 x scan length, with the units mGy-cm. 

3577 Dose notification value - A value of CTDIvol (in units of mGy) or of DLP (in units of 

3578 mGy·cm) 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 = ΣT (wT HT), in which 

3586 HT is the equivalent dose in tissue or organ T and wT is the tissue weighting factor for 

tissue or organ T. The unit of E and HT is joule per kilogram (J kg–1 3587 ), with the special 

3588 name sievert (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 2011a). The unit for HT is 

J kg–1 3594 , with the special name sievert (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 

kilogram (C kg–1). The special unit for exposure is roentgen (R), where 1 R = 2.58 × 10–4 3606 C 

kg–1 3607 . 

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 
 81 

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 

= 1 J kg–1 3626 (see rad, rem, gray, and Sievert) 

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 (IAEA 2011a)) 

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) 
 82 

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 2011a) 

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., x3675 rays) in a material of mass δm (IAEA 2011a). 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 

and the area of the irradiated field and is measured in Gy·cm2

3679 , 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 2011a) 

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-to3695 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 (IAEA 2011a) 

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 (IAEA 2011a) 
 83 

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 (NCRP 2003) 

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 (NCRP 2003). 

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). 

3722 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 2011a) 

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 
 84 

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 2011a) 

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 

Rad – the special (traditional or historical) name for the unit of absorbed dose. 1 rad = 0.01 J kg3776 

1

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 2011a) 

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 2011a) (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). 
 85 

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 2011a) (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 

equal to the absorbed dose (D) in rad, modified by a quality factor (Q). 1 rem = 0.01 J kg-1 3805 . In 

3806 the SI system of units, it is replaced by the special name sievert (Sv), which is numerically 

3807 equal to the absorbed dose (D) in gray modified by a radiation weighting factor (ωR). 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 object of given contrast that 

3811 is just perceptible. The resolution actually achieved with imaging lower contrast objects 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 

standard conditions. 1 R = 2.58 x 10-4 coulombs per kilogram (C kg-1 3818 ) (NCRP 2003). 

3819 Screening – the evaluation of an asymptomatic person in a population to detect a disease process 

3820 not known to exist 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 

SI unit of equivalent dose is the J kg-1 3824 , and is abbreviated HT. It is numerically equal to a 

3825 radiation weighting factor (ωR) [or quality factor (Q)] multiplied by the absorbed dose in 

3826 tissue T (DT,R). 1 Sv = 100 rad (NCRP 2003). The formula is: 

3827 HT = ∑R ωR DT,R or ∑R QR DT,R 

3828 where 

3829 ωR = 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 

unit of effective dose is the J kg-1 3835 , and is abbreviated HE. It is numerically equal to a radiation 

3836 weighting factor (ωR) multiplied by a tissue weighting factor (ωT) 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 = ∑T ωT ∑R ωR DT,R = ∑T HT ωT 

3840 where 

3841 HE = the effective dose (or effective dose equivalent) to the entire individual, 

3842 ωT = the tissue weighting factor in tissue T, 
 86 

3843 HT = the equivalent dose (or dose equivalent), 

3844 ωR = the radiation weighting factor, and 

3845 DT,R = the absorbed dose to tissue T from radiation type R. 

3846 (see rad, rem, gray, and Sievert) 

3847 Signal to noise ratio – the ratio of input signal to background interference. The greater the ratio, 

3848 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 

3873 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 2011a) 

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) 
 87 

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 2011a) 
A-1 

3891 

3892 APPENDIX A – NIH INFORMED CONSENT TEMPLATES 

3893 

3894 

3895 The guidance in this appendix is suitable for research involving diagnostic and interventional x3896 ray procedures. It applies to radiation use indicated for research involving human subjects. 

3897 Examples might include evaluating new mammography protocol using lower kVp as 

3898 recommended by ICRP, virtual colonoscopy, and national lung screening trials. It excludes 

3899 radiation oncology research, in which radiation doses to subjects may be much higher. A 

3900 discussion of human subjects research ethics, patient benefit:risk considerations, and the role of 

3901 Institutional Review Boards is beyond the scope of this document, but is an essential process 

3902 prior to the conduct of research involving human subjects. 

3903 

3904 The risk from research protocols involving radiation use indicated for research, as described 

3905 above, can be categorized into groups. A useful approach is to group risk as minimal, minor to 

3906 intermediate, or moderate. The templates on the following pages are adapted from those used by 

3907 the NIH in 2012 (less than 1 mSv (100 mrem) “minimal” and 1-50 mSv (100 mrem – 5 rem) 

3908 “minor to intermediate”). Doses above 50 mSv (5 rem) may be considered to range from 

3909 moderate to substantial. The specific ranges and text may be adjusted as required by the specific 

3910 IRB (NIH 2001; NIH 2008a; NIH 2008b; NIH 2010). Another approach to selecting the dose 

3911 ranges and descriptors for these templates is shown below. 

3912 

Classification schemes for use of E as a qualitative indicator of stochastic risk for diagnostic and 

interventional x-ray procedures 

Range of E 

(mSv) 

Radiation Risk Descriptor Expected Minimum 

ICRP Martin (2007) NCRP Individual or Societal Benefit 

<0.1 Trivial Negligible Negligible Describable 

0.1-1 Minor Minimal Minimal Minor 

1-10 Intermediate Very low Minor Moderate 

10-100 Moderate Low Low Substantial 

>100 - - Acceptable (in 

context of the 

expected benefit)

Justifiable expectation of very 

substantial individual benefit 

Adapted from: (ICRP 1991b; Martin 2007) 

3913 

3914 

3915 
 A-2 

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-3 

3945 MINOR TO INTERMEDIATE RISK 

3946 Adapted from NIH TEMPLATE B (1 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 PARAGRAPH 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.
 REF-1 

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. AAPM Report No. 94: validating Automatic Film Processor Performance. 

4004 American Association of Physicists in Medicine. 

4005 AAPM. 2006c. AAPM Report Task Group 108: PET and PET/CT Shielding requirements. 

4006 Medical Physics 33(1):4-15. 

4007 AAPM. 2009. AAPM Report No. 116: An Exposure Indicator for Digital Radiography. College 

4008 Park, MD: American Association of Physicists in Medicine. 

4009 ACR. 2006a. ACR practice guideline on informed consent for image-guided procedures. Practice 

4010 Guidelines and Technical Standards 2007. Reston, VA: American College of Radiology. 

4011 ACR. 2006b. ACR technical standard for diagnostic medical physics performance monitoring of 

4012 radiographic and fluoroscopic equipment. Practice Guidelines and Technical Standards 

4013 2007. Reston, VA: American College of Radiology. 

4014 ACR. 2007a. ACR practice guideline for digital radiography. Practice Guidelines and Technical 

4015 Standards 2007. Reston, VA American College of Radiology. 

4016 ACR. 2007b. ACR technical standard for diagnostic medical physics performance monitoring of 

4017 computed tomography (CT) equipment. Practice Guidelines and Technical Standards 

4018 2007. Reston, VA: American College of Radiology. 

4019 ACR. 2007c. ACR technical standard for electronic practice of medical imaging. Practice 

4020 Guidelines and Technical Standards 2007. Reston, VA: American College of Radiology. 

4021 ACR. 2007d. American College of Radiology white paper on radiation dose in medicine. J Am 

4022 Coll Radiol 4:13. 

4023 ACR. 2008a. ACR-SSR practice guideline for the performance of dual-energy x-ray 

4024 absorptiometry (DXA). Practice Guidelines and Technical Standards 2007. Reston, VA: 

4025 American College of Radiology. 

4026 ACR. 2008b. ACR practice guideline for diagnostic reference levels in medical X-ray imaging. 

4027 Practice Guidelines and Technical Standards 2008. Reston, VA: American College of 

4028 Radiology. p 799-804. 

4029 ACR. 2008c. ACR technical standard for management of the use of radiation in fluoroscopic 

4030 procedures. Practice Guidelines and Technical Standards 2008. Reston, VA American 

4031 College of Radiology. p 1143-1149. 

4032 ACR. 2009a. ACR-SIIM practice guideline for electronic medical information privacy and 

4033 security. Practice Guidelines and Technical Standards 2007. Reston, VA: American 

4034 College of Radiology. 
 REF-2 

4035 ACR. 2009b. ACR practice guideline for the performance of computed tomography (CT) 

4036 colonography in adults. Practice Guidelines and Technical Standards 2007. Reston, VA: 

4037 American College of Radiology. 

4038 ACR. 2010. ACR practice guideline for communication of diagnostic imaging findings. Reston, 

4039 VA: American College of Radiology. 

4040 ACR. 2012. ACR appropriateness criteria. Practice Guidelines and Technical Standards 2007, 

4041 Last update 2012. Reston, VA: American College of Radiology. 

4042 ADA FDA. 2004 The selection of patients for dental radiographic examinations. 

4043 Amis ES, Jr., Butler PF, Applegate KE, Birnbaum SB, Brateman LF, Hevezi JM, Mettler FA, 

4044 Morin RL, Pentecost MJ, Smith GG and others. 2007. American College of Radiology 

4045 white paper on radiation dose in medicine. J Am Coll Radiol 4(5):272-84. 

4046 Aroua A, Rickli H, Stauffer JC, Schnyder P, Trueb PR, Valley JF, Vock P, Verdun FR. 2007. 

4047 How to set up and apply reference levels in fluoroscopy at a national level. Eur Radiol 

4048 17(6):1621-33. 

4049 Balter S, Hopewell JW, Miller DL, Wagner LK, Zelefsky MJ. 2010. Fluoroscopically guided 

4050 interventional procedures: a review of radiation effects on patients' skin and hair. 

4051 Radiology 254(2):326-41. 

4052 Balter S, Miller DL. 2007. The new Joint Commission sentinel event pertaining to prolonged 

4053 fluoroscopy. Journal of the American College of Radiology 4(7):497-500. 

4054 Balter S, Miller DL, Vano E, Ortiz Lopez P, Bernardi G, Cotelo E, Faulkner K, Nowotny R, 

4055 Padovani R, Ramirez A. 2008. A pilot study exploring the possibility of establishing 

4056 guidance levels in x-ray directed interventional procedures. Med Phys 35(2):673-80. 

4057 Balter S, Moses J. 2007. Managing patient dose in interventional cardiology. Catheterization and 

4058 Cardiovascular Diagnosis 70:244-249. 

4059 Balter S, Shope TB, Jr., Fletcher DW, Kuan HM, Chan RC. 2002. Techniques to estimate 

4060 radiation dose to skin during fluoroscopically guided procedures. Intravascular 

4061 brachytherapy. Fluoroscopically guided interventions. Madison, WI: Medical Physics 

4062 Publishing. p 731-764. 

4063 Berrington de González A, Mahesh M, Kim K, et al. 2009. PRojected cancer risks from 

4064 computed tomographic scans performed in the united states in 2007. Archives of Internal 

4065 Medicine 169(22):2071-2077. 

4066 Bleeser F, Hoornaert MT, Smans K, Struelens L, Buls N, Berus D, Clerinx P, Hambach L, 

4067 Malchair F, Bosmans H. 2008. Diagnostic reference levels in angiography and 

4068 interventional radiology: a Belgian multi-centre study. Radiat Prot Dosimetry 129(1-

4069 3):50-5. 

4070 Bonnick SL, L. L. 2006. Bone densitometry for technologists: Humana Press. 

4071 Brambilla M, Marano G, Dominietto M, Cotroneo AR, Carriero A. 2004. Patient radiation doses 

4072 and references levels in interventional radiology. Radiol Med 107(4):408-18. 

4073 Brenner D, Elliston C, Hall E, Berdon W. 2001. Estimated risks of radiation-induced fatal cancer 

4074 from pediatric CT. AJR Am J Roentgenol 176(2):289-96. 

4075 Brenner DJ, Hall E.J. 2007. Computed Tomography — An Increasing Source of Radiation 

4076 Exposure. New England Journal of Medicine 357:2277-2284. 

4077 Carter J. 1978. Title 3 - The President: Radiation protection guidance to Federal agencies for 

4078 diagnostic x-rays. In: Department E, editor. Washington, DC: Federal Register. p 4377-

4079 4380. 
 REF-3 

4080 Carter J. 1980. Executive Order 12196: Occupational Safety and Health Programs for Federal 

4081 Employees. In: President Oot, editor. Washington, DC: White House. 

4082 CDC. 2003. Guidelines for Infection Control in Dental Health-Care Settings --- 2003. In: 

4083 Prevention CfDCa, editor. Atlanta, GA: Morbidity and Mortality Daily Report. p 1-61. 

4084 Chambers CE, Fetterly KA, Holzer R, Lin PJ, Blankenship JC, Balter S, Laskey WK. 2011. 

4085 Radiation safety program for the cardiac catheterization laboratory. Catheterization and 

4086 Cardiovascular Interventions 77(4):546-56. 

4087 Chanaud CM. 2008. Determination of required content of the informed consent process for 

4088 human participants in biomedical research conducted in the U.S.: A practical tool to 

4089 assist clinical investigators. Contemporary Clinical Trials 29(4):501-506. 

4090 Compagnone G, Baleni MC, Pagan L, Calzolaio FL, Barozzi L, Bergamini C. 2006. Comparison 

4091 of radiation doses to patients undergoing standard radiographic examinations with 

4092 conventional screen-film radiography, computed radiography and direct digital 

4093 radiography. British Journal of Radiology 79(947):899-904. 

4094 Congress. 2004. OSH Act of 1970 as amended, Section 19, Federal agency safety programs and 

4095 responsibilities. In: Congress US, editor. 

4096 Congress. 2007. Health Information Technology for Economic and Clinical Health Act 

4097 (HITECH Act). XIII. 

4098 D'Helft CJ, Brennan PC, McGee AM, McFadden SL, Hughes CM, Winder JR, Rainford LA. 

4099 2009. Potential Irish dose reference levels for cardiac interventional examinations. Br J 

4100 Radiol 82(976):296-302. 

4101 DHHS. 2012a. 42CFR410.32: Diagnostic x-ray tests, diagnostic laboratory tests, and other 

4102 diagnostic tests: Conditions. In: Services DoHaH, editor. Title 42 Code of Federal 

4103 Regulations Part 410.32. 

4104 DHHS. 2012b. 45CFR164: Security and privacy. In: Services DoHaH, editor. Title 45 Code of 

4105 Federal Regulations Part 164. 

4106 Dunn NL, Ha M, Radosevich AT. 2012. Main Group Redox Catalysis: Reversible P(III)/P(V) 

4107 Redox Cycling at a Phosphorus Platform. Journal of the American Chemical Society 2:2. 

4108 EPA. 1976. Federal Guidance Report No. 9: Radiation Protection Guidance for Diagnostic X 

4109 Rays. 

4110 EPA. 2000. Radiation protection at EPA: The first 30 years. 

4111 EPA. 2012. TItle 42 U.S.C. 2021(h): Cooperation with states - Consultative, advisory, and 

4112 miscellaneous functions of Administrator of Environmental Protection Agency. In: 

4113 Congress US, editor. 

4114 FDA. 1994. Avoidance of serious x-ray induced skin injuries to patients during fluoroscopically4115 guided procedures. In: Administration FaD, editor. 

4116 FDA. 2001. FDA Public Health Notification: Reducing Radiation Risk from Computed 

4117 Tomography for Pediatric and Small Adult Patients. In: Administration FaD, editor. 

4118 FDA. 2010a. National Exposure to X-ray Trends. In: Administration FaD, editor. 

4119 FDA. 2010b. Safety investigation of CT brain perfusion scans: Update 12/8/2009. In: 

4120 Administration FaD, editor. 

4121 FDA. 2012a. 21CFR803.3: How does FDA define the terms used in this part? In: Administration 

4122 FaD, editor. Title 21 Code of Federal Regulations Part 803.3. 

4123 FDA. 2012b. 21CFR803: Medical device reporting. In: Administration FaD, editor. Title 21 

4124 Code of Federal Regulations Part 803. 
 REF-4 

4125 FDA. 2012c. 21CFR900: Mammography. In: Administration FaD, editor. Title 21 Code of 

4126 Federal Regulations Part 900. 

4127 FDA. 2012d. 21CFR1020.32: Performance standards for ionizing radiation emitting products - 

4128 Fluoroscopic equipment. 

4129 FDA. 2012e. 21CFR1020: Performance standards for ionizing radiation emitting products. In: 

4130 Administration FaD, editor. Title 21 Code of Federal Regulations Part 1020. 

4131 FDA. 2012f. 21CFR 1020.30: Performance standards for ionizing radiation emitting products - 

4132 Diagnostic x-ray systems and their major components. In: Administration FaD, editor. 

4133 Title 21 Code of Federal Regulations Part 1020.30. 

4134 FDA. 2012g. 21CFR Subchapter J: Radiological health (parts 1000-1050). In: Administration 

4135 FaD, editor. Title 21 Code of Federal Regulations Subchapter J 

4136 Fletcher DW, Miller DL, Balter S, Taylor MA. 2002. Comparison of four techniques to estimate 

4137 radiation dose to skin during angiographic and interventional radiology procedures. 

4138 Journal of Vascular and Interventional Radiology 13(4):391-397. 

4139 Freedman M, Pe E, Mun S, So S-C, Nelson M. 1993. The potential for unnecessary patient 

4140 exposure from the use of storage phosphor imaging systems. Kim Y, editor. Medical 

4141 Imaging 1993: Image Capture, Formatting, and Display. 

4142 Genant HK, Jergas M, Palermo L, Nevitt M, Valentin RS, Black D, SR. C. 1996. Comparison of 

4143 semiquantitative visual and quantitative morphometric assessment of prevalent and 

4144 incident vertebral fractures in osteoporosis: The study of osteoporotic fractures research 

4145 group. J Bone Miner Res 11(7):984-996. 

4146 Gibbs SJ. 2000. Effective dose equivalent and effective dose: Comparison for common 

4147 projections in oral and maxillofacial radiology. Oral Surgery, Oral Medicine, Oral 

4148 Pathology, Oral Radiology, and Endodontology 90(4):538-545. 

4149 Goren A, Bonvento M, Biernacki J, Colosi D. 2008. Radiation exposure with the NOMAD 

4150 portable X-ray system. Dentomaxillofac Radiol 37(2):109-112. 

4151 Goske MJ, Applegate KE, Boylan J, Butler PF, Callahan MJ, Coley BD, Farley S, Frush DP, 

4152 Hernanz-Schulman M, Jaramillo D and others. 2008. The Image Gently campaign: 

4153 working together to change practice. AJR Am J Roentgenol 190(2):273-274. 

4154 Gray JE, Archer BR, Butler PF, Hobbs BB, Mettler FA, Jr., Pizzutiello RJ, Jr., Schueler BA, 

4155 Strauss KJ, Suleiman OH, Yaffe MJ. 2005. Reference values for diagnostic radiology: 

4156 application and impact. Radiology 235(2):354-8. 

4157 Harrison JD, Streffer C. 2007. The ICRP protection quantities, equivalent and effective dose: 

4158 their basis and application. Radiat Prot Dosimetry 127(1-4):12-8. 

4159 Hart D, Hillier MC, Wall BF. 2009. National reference doses for common radiographic, 

4160 fluoroscopic and dental X-ray examinations in the UK. Br J Radiol 82(973):1-12. 

4161 Hirshfeld JW, Jr., Balter S, Brinker JA, Kern MJ, Klein LW, Lindsay BD, Tommaso CL, Tracy 

4162 CM, Wagner LK. 2004. ACCF/AHA/HRS/SCAI clinical competence statement on 

4163 physician knowledge to optimize patient safety and image quality in fluoroscopically 

4164 guided invasive cardiovascular procedures: a report of the American College of 

4165 Cardiology Foundation/American Heart Association/American College of Physicians 

4166 Task Force on Clinical Competence and Training. Journal of the American College of 

4167 Cardiology 44(11):2259-2282. 

4168 IAEA. 1996. Safety Series No. 115: International basic safety standards for protection against 

4169 ionizing raidiation and the safety of radiation sources. Vienna: International Atomic 

4170 Energy Agency. 
 REF-5 

4171 IAEA. 2009. Establishing guidance levels in x ray guided medical interventional procedures: A 

4172 pilot study. Safety Reports Series No. 59. Vienna: International Atomic Energy Agency. 

4173 IAEA. 2011a. IAEA SAFETY STANDARDS SERIES No. GSR Part 3 (Interim): Radiation 

4174 protection and safety of radiation sources - International Basic Safety Standards. Vienna: 

4175 International Atomic Energy Agency. 

4176 IAEA. 2011b. IAEA Safety Standards: Radiation Protection and Safety of Radiation Sources - 

4177 IARC. 2012. Agents Classified by the IARC Monographs, Volumes 1–105. Lyon: International 

4178 Agency for Research on Cancer, World Health Organization. 

4179 ICRP. 1991a. ICRP Publication No. 60: 1990 Recommendations of the International 

4180 Commission on Radiological Protection. International Commission on Radiological 

4181 Protection. Annals of the ICRP 21(1-3):1-201. 

4182 ICRP. 1991b. ICRP Publication No. 62: Radiological protection in biomedical research : A 

4183 report of Committee 3 adopted by the International Commission on Radiological 

4184 Protection. International Commission on Radiological Protection. Ann ICRP 22(3). 

4185 ICRP. 1996. ICRP Publication No. 73: Radiologcal protection and safety in medicine. Oxford: 

4186 Pergamon Press. 

4187 ICRP. 2000a. ICRP Publication No. 85: Avoidance of radiation injuries from medical 

4188 interventional procedures. International Commission on Radiological Protection. Annals 

4189 of the ICRP 30(2):7-67. 

4190 ICRP. 2000b. ICRP Publication No. 87: Managing patient dose in computed tomography. 

4191 Oxford: Pergamon Press. 

4192 ICRP. 2003. Diagnostic reference levels in medical imaging: review and additional advice. 

4193 ICRP online educational reference.: International Commission on Radiological 

4194 Protection. 

4195 ICRP. 2004. ICRP Publication No. 93: Manating patient dose in digital radiology. International 

4196 Commission on Radiological Protection. Ann ICRP. Oxford: Pergamon Press. 

4197 ICRP. 2007a. ICRP Publication No. 103: The 2007 Recommendations of the International 

4198 Commission on Radiological Protection. International Commission on Radiological 

4199 Protection. Ann ICRP 37(2-4):1-332. 

4200 ICRP. 2007b. ICRP Publication No. 103: The 2007 Recommendations of the International 

4201 Commission on Radiological Protection.: International Commission on Radiological 

4202 Protection. 1-332 p. 

4203 ICRP. 2007c. ICRP Publication No. 105: Radiation protection in medicine. International 

4204 Commission on Radiological Protection. Ann ICRP 37(6):1-63. 

4205 ICRP. 2012. ICRP Publication No. 120: Radiological Protection in Cardiology. Ann ICRP 41(3). 

4206 ICRU. 2005, or most current version. ICRU Report 74: Patient dosimetry for X rays used in 

4207 medical imaging. International Commission on Radiation Units & Measurements. Journal 

4208 of the ICRU 5(2):1-113. 

4209 IEC. 2008. IEC Report 62494-1: Medical electrical equipment - Exposure index of digital x-ray 

4210 imaging systems - Part 1: Definitiona and requirements for general radiography. 

4211 International Electrotechnical Commission. 

4212 IEC. 2010. IEC Report 60601: Medical electrical equipment - Part 2-43: Particular requirements 

4213 for the safety of X-ray equipment for interventional procedures. Geneva, Switzerland: 

4214 International Electrotechnical Commission. Report nr 60601-2-43. 
 REF-6 

4215 IHE. 2008. IHE Radiology Technical Framework Supplement 2007-2008 (public comment 

4216 draft): Radiation exposure monitoring (REM) integration profile. Integrating the 

4217 Healthcare Enterprise. 

4218 ISCD. 2007a. Official positions of the International Society for Clinical Densitometry. West 

4219 Hartford, CT: International Society for Clinical Densitometry. 

4220 ISCD. 2007b. Pediatric Official Positions of the International Society for Clinical Densitometry. 

4221 W. Hartford, CT: International Society for Clinical Densitometry. 

4222 ISCD. 2012. ISCD home page. International Society for Clinical Densitometry. 

4223 Kanis JA, Melton LJ, 3rd, Christiansen C, Johnston CC, Khaltaev N. 1994. The diagnosis of 

4224 osteoporosis. Journal of Bone and Mineral Research 9(8):1137-41. 

4225 Kwon D, Little MP, Miller DL. 2011. Reference air kerma and kerma-area product as estimators 

4226 of peak skin dose for fluoroscopically guided interventions. Medical Physics 38(7):4196-

4227 204. 

4228 Lipsitz EC, Veith FJ, Ohki T, Heller S, Wain RA, Suggs WD, Lee JC, Kwei S, Goldstein K, 

4229 Rabin J and others. 2000. Does the endovascular repair of aortoiliac aneurysms pose a 

4230 radiation safety hazard to vascular surgeons? Journal of Vascular Surgery 32(4):704-710. 

4231 MacDonald JC, Reid JA, Berthoty D. 1983. Drywall construction as a dental radiation barrier. 

4232 Oral Surgery, Oral Medicine, Oral Pathology 55(3):319-26. 

4233 Mahesh M. 2008. How to prepare for the Joint Commission's sentinel event policy pertaining to 

4234 prolonged fluoroscopy. J Am Coll Radiol 5(4):601-3.

4235 Martin CJ. 2007. Effective dose: how should it be applied to medical exposures? Br J Radiol 

4236 80(956):639-47. 

4237 Masih S, Morrison L, Massoth R, Taylor T, Maxwell P. 2006. Working with a Hand-Held Dental 

4238 X-Ray Unit : Equipment Evaluation. 

4239 McCollough CH. 2008. CT dose: how to measure, how to reduce. Health Phys 95(5):508-17. 

4240 McNitt-Gray MF. 2002. AAPM/RSNA Physics Tutorial for Residents: Topics in CT. Radiation 

4241 dose in CT. Radiographics 22(6):1541-53. 

4242 Mettler FA, Jr., Huda W, Yoshizumi TT, Mahesh M. 2008. Effective doses in radiology and 

4243 diagnostic nuclear medicine: a catalog. Radiology 248(1):254-63. 

4244 Miles DA, Van Dis ML, Peterson MG. 1989. Information yield: a comparison of Kodak T-Mat 

4245 G, Ortho L and RP X-Omat films. Dento-Maxillo-Facial Radiology 18(1):15-8. 

4246 Miller DL. 2008. Overview of contemporary interventional fluoroscopy procedures. Health Phys 

4247 95(5):638-44. 

4248 Miller DL, Balter S, Cole PE, Lu HT, Berenstein A, Albert R, Schueler BA, Georgia JD, Noonan 

4249 PT, Russell E and others. 2003a. Radiation doses in interventional radiology procedures: 

4250 The RAD-IR study Part II. Skin dose. Journal of Vascular and Interventional Radiology 

4251 14(8):977-990. 

4252 Miller DL, Balter S, Cole PE, Lu HT, Schueler BA, Geisinger M, Berenstein A, Albert R, 

4253 Georgia JD, Noonan PT and others. 2003b. Radiation doses in interventional radiology 

4254 procedures: The RAD-IR study Part I. Overall measures of dose. Journal of Vascular and 

4255 Interventional Radiology 14(6):711-727. 

4256 Miller DL, Balter S, Dixon RG, Nikolic B, Bartal G, Cardella JF, Dauer LT, Stecker MS. 2012. 

4257 Quality improvement guidelines for recording patient radiation dose in the medical 

4258 record for fluoroscopically guided procedures. Journal of Vascular and Interventional 

4259 Radiology 23(1):11-8. 
 REF-7 

4260 Miller DL, Balter S, Noonan PT, Georgia JD. 2002. Minimizing radiation-induced skin injury in 

4261 interventional radiology procedures. Radiology 225(2):329-336. 

4262 Miller DL, Balter S, Schueler BA, Wagner LK, Strauss KJ, Vano E. 2010a. Clinical radiation 

4263 management for fluoroscopically guided interventional procedures. Radiology 

4264 257(2):321-32. 

4265 Miller DL, Balter S, Wagner LK, Cardella JF, Clark TWI, Neithamer CD, Jr., Schwartzberg MS, 

4266 Swan TL, Towbin RB, Rholl KS and others. 2004. Quality improvement guidelines for 

4267 recording patient radiation dose in the medical record. J Vasc Interv Radio 15(5):423-

4268 429. 

4269 Miller DL, Kwon D, Bonavia GH. 2009. Reference levels for patient radiation doses in 

4270 interventional radiology: proposed initial values for U.S. practice. Radiology 253(3):753-

4271 764. 

4272 Miller DL, Vano E, Bartal G, Balter S, Dixon R, Padovani R, Schueler B, Cardella JF, de Baere 

4273 T. 2010b. Occupational radiation protection in interventional radiology: A joint guideline 

4274 of the Cardiovascular and Interventional Radiology Society of Europe and the Society of 

4275 Interventional Radiology. Cardiovasc Intervent Radiol 33(2):230-9. 

4276 NCRP. 1988. NCRP Report No. 99: Quality assurance for diagnostic imaging. Bethesda, MD: 

4277 National Council on Radiation Protection and Measurements. 

4278 NCRP. 1989a. NCRP Report No. 100: Exposure of the U.S. population from diagnostic medical 

4279 radiation. Bethesda, MD: National Council on Radiation Protection and Measurements. 

4280 NCRP. 1989b. NCRP Report No. 102: Medical X-ray, Electron Beam and Gamma-ray 

4281 Protection for Energies Up to 50 MeV (Equipment Design, Performance, and Use 

4282 (Supersedes NCRP Report No. 33). . Bethesda, MD. 

4283 NCRP. 1990. NCRP Report No. 107: Implementation of the principle of ALARA for medical 

4284 and dental personnel. Bethesda, MD: National Council on Radiation Protection and 

4285 Measurements. 

4286 NCRP. 1995. NCRP Report No. 122: Use of personal monitors to estimate effective dose 

4287 equivalent and effective dose to workers for external exposure to low-LET radiation. 

4288 Bethesda, MD: National Council on Radiation Protection and Measurements. 

4289 NCRP. 2000. NCRP Report No. 133: Radiation protection for procedures performed outside the 

4290 radiology department. Bethesda, MD: National Council on Radiation Protection and 

4291 Measurements. 

4292 NCRP. 2003. NRCP Report No. 145: Radiation protection in dentistry. Bethesda, MD: National 

4293 Council on Radiation Protection and Measurements. 

4294 NCRP. 2004a. NCRP Report No. 147: Structural shielding design for medical x-ray imaging 

4295 facilities. Bethesda, MD: National Council on Radiation Protection and Measurements. 

4296 NCRP. 2004b. NCRP Report No. 148: Radiation protection in veterinary medicine. Bethesda, 

4297 MD: National Council on Radiation Protection and Measurements. 

4298 NCRP. 2009. NCRP Report No. 160: Ionizing radiation exposure of the population of the United 

4299 States. Bethesda, MD: National Council on Radiation Protection and Measurements. 

4300 NCRP. 2010. NCRP Report No. 168: Radiation dose management for fluoroscopically guided 

4301 interventional medical procedures. Bethesda, MD: National Council on Radiation 

4302 Protection and Measurements. 

4303 NEMA. 2009. NEMA PS 3.14: Digital Imaging and Communications in Medicine (DICOM) 

4304 Part 14: Grayscale Standard Display Function. In: Association NEM, editor. 
 REF-8 

4305 Neofotistou V, Vano E, Padovani R, Kotre J, Dowling A, Toivonen M, Kottou S, Tsapaki V, 

4306 Willis S, Bernardi G and others. 2003. Preliminary reference levels in interventional 

4307 cardiology. Eur Radiol 13(10):2259-63. 

4308 NHS. 1993. What do we mean by appropriate health care? Report of a working group prepared 

4309 for the Director of Research and Development of 

4310 the NHS Management Executive, National Health Service. Quality in Health Care 2(2):117-123. 

4311 NIH. 2001. Improving informed consent for research radiation studies. National Institutes of 

4312 Health. 

4313 NIH. 2008a. Informed consent template B: Radiation exposure consent language (less than 5 rem 

4314 effective dose) 

4315 NIH. 2008b. Informed consent template C: Total effective dose > 5 rem. In: Health NIo, editor. 

4316 NIH. 2010. Informed Consent Template A: Total effective dose less than or equal to 0.3 rem. 

4317 National Institutes of Health. 

4318 NIH NCI SIR. 2005. NIH Publication No. 05-5286: Interventional Fluoroscopy: Reducing 

4319 Radiation Risks for Patients and Staff. National Institutes of Health, National Cancer 

4320 Institute and The Society of Interventional Radiology. 

4321 NRPB. 1990. Patient dose reduction in diagnostic radiology: Report by the Royal College of 

4322 Radiologists and the National Radiological Protection Board. London: National Radiation 

4323 Protection Board. 1-46 p. 

4324 NTP. 2011. Twelfth Report on Carcinogens. Department of Health and Human Services, 

4325 National Toxicology Program. 

4326 O'Dea TJ, Geise RA, Ritenour ER. 1999. The potential for radiation-induced skin damage in 

4327 interventional neuroradiological procedures: a review of 522 cases using automated 

4328 dosimetry. Med Phys 26(9):2027-33. 

4329 Orth RC, Wallace MJ, Kuo MD. 2008. C-arm Cone-beam CT: General Principles and Technical 

4330 Considerations for Use in Interventional Radiology. Journal of Vascular and 

4331 Interventional Radiology 19(6):814-20. 

4332 OSHA. 2012. 29CFR1910.1096: Ionizing radiation. In: Administration OSH, editor. Title 29 

4333 Code of Federal Regulations Part 1910.1096. 

4334 OSTP, USDA, DOE, NASA, DOC, CPSC, IDCAAID, HUD, DOJ, DoD and others. 1991. 

4335 56FR28002-28032: Federal policy for the protection of human subjects. In: rule Mc, 

4336 editor: Federal Register. p 28002-28032. 

4337 Padovani R, Quai E. 2005. Patient dosimetry approaches in interventional cardiology and 

4338 literature dose data review. Radiat Prot Dosimetry 117(1-3):217-221. 

4339 Paterson A, Frush DP, Donnelly LF. 2001. Helical CT of the body: are settings adjusted for 

4340 pediatric patients? AJR. American Journal of Roentgenology 176(2):297-301. 

4341 Peterzol A, Quai E, Padovani R, Bernardi G, Kotre CJ, Dowling A. 2005. Reference levels in 

4342 PTCA as a function of procedure complexity. Radiation Protection Dosimetry 117(1-

4343 3):54-58. 

4344 Scarfe WC, Farman AG, Sukovic P. 2006. Clinical applications of cone-beam computed 

4345 tomography in dental practice. Journal / Canadian Dental Association. Journal de l 

4346 Association Dentaire Canadienne 72(1):75-80. 

4347 Seibert JA, Shelton DK, Moore EH. 1996. Computed radiography X-ray exposure trends. 

4348 Academic Radiology 3(4):313-8. 

4349 Sidhu MK, Goske MJ, Coley BJ, Connolly B, Racadio J, Yoshizumi TT, Utley T, Strauss KJ. 

4350 2009. Image gently, step lightly: increasing radiation dose awareness in pediatric 
 REF-9 

4351 interventions through an international social marketing campaign. J Vasc Interv Radiol 

4352 20(9):1115-9. 

4353 Sistrom CL. 2008. In support of the ACR Appropriateness Criteria®. Journal of the American 

4354 College of Radiology 5(5):630-5; discussion 636-7. 

4355 Smith-Bindman R, Lipson J, Marcus R, Kim KP, Mahesh M, Gould R, Berrington de Gonzalez 

4356 A, Miglioretti DL. 2009. Radiation dose associated with common computed tomography 

4357 examinations and the associated lifetime attributable risk of cancer. Arch Intern Med 

4358 169(22):2078-86. 

4359 Stecker MS, Balter S, Towbin RB, Miller DL, Vañó E, Bartal G, Angle JF, Chao CP, Cohen 

4360 AM, Dixon RG and others. 2009. Guidelines for patient radiation dose management. J 

4361 Vasc Interv Radiol 20(7S):S263-S273. 

4362 Stedman. 2006. Stedman's Medical Dictionary. In: Wilkins LW, editor. 28th ed. 

4363 Steele JR, Jones AK, Ninan EP. 2012. Quality initiatives: Establishing an interventional 

4364 radiology patient radiation safety program. Radiographics 32(1):277-87. 

4365 Strauss KJ, Goske MJ, Kaste SC, Bulas D, Frush DP, Butler P, Morrison G, Callahan MJ, 

4366 Applegate KE. 2010. Image gently: Ten steps you can take to optimize image quality and 

4367 lower CT dose for pediatric patients. AJR Am J Roentgenol 194(4):868-73. 

4368 Suzuki S, Furui S, Kohtake H, Yokoyama N, Kozuma K, Yamamoto Y, Isshiki T. 2006. 

4369 Radiation exposure to patient's skin during percutaneous coronary intervention for 

4370 various lesions, including chronic total occlusion. Circ.J. 70:44-48. 

4371 The Joint Commission. 2006. Sentinel event: Radiation overdose FAQs. 

4372 The Joint Commission. 2012a. Accreditation Program: Hospital National Patient Safety Goals. 

4373 In: Commission TJ, editor. p 11-13. 

4374 The Joint Commission. 2012b. Universal Protocol web page. The Joint Commission. 

4375 Tsalafoutas IA, Goni H, Maniatis PN, Pappas P, Bouzas N, Tzortzis G. 2006. Patient doses from 

4376 noncardiac diagnostic and therapeutic interventional procedures. Journal of Vascular and 

4377 Interventional Radiology 17(9):1489-98. 

4378 USNRC. 2012a. 10CFR20.1003: Definitions. In: Commission NR, editor. Title 10 Code of 

4379 Federal Regulations Part 20.1003. 

4380 USNRC. 2012b. 10CFR20.1208: Dose equivalent to an embryo/fetus. In: Commission NR, 

4381 editor. Title 10 Code of Federal Regulations Part 20.1208. 

4382 USNRC. 2012c. 10CFR20: Standards for protection against radiation. In: Commission NR, 

4383 editor. Title 10 Code of Federal Regulations Part 20. 

4384 USNRC. 2012d. 10CFR35: Medical use of radioactive material. In: Commission UNR, editor. 

4385 Vano E. 2003. Radiation exposure to cardiologists: how it could be reduced. Heart 89(10):1123-

4386 4. 

4387 Vañó E, Gonzalez L. 2001. Approaches to establishing reference levels in interventional 

4388 radiology. Radiat Prot Dosimetry 94(1-2):109-112. 

4389 Vano E, Järvinen H, Kosunen A, Bly R, Malone J, Dowling A, Larkin A, Padovani R, Bosmans 

4390 H, Dragusin O and others. 2008a. Patient dose in interventional radiology: a European 

4391 survey. Radiat Prot Dosimetry 129(1-3):39-45. 

4392 Vano E, Sanchez R, Fernandez JM, Gallego JJ, Verdu JF, de Garay MG, Azpiazu A, Segarra A, 

4393 Hernandez MT, Canis M and others. 2009. Patient dose reference levels for 

4394 interventional radiology: a national approach. Cardiovasc Intervent Radiol 32(1):19-24. 
 REF-10 

4395 Vano E, Segarra A, Fernandez JM, Ordiales JM, Simon R, Gallego JJ, Del Cerro J, Casasola E, 

4396 Verdu JF, Ballester T and others. 2008b. A pilot experience launching a national dose 

4397 protocol for vascular and interventional radiology. Radiat Prot Dosimetry 129(1-3):46-9. 

4398 Verdun FR, Aroua A, Trueb PR, Vock P, Valley JF. 2005. Diagnostic and interventional 

4399 radiology: a strategy to introduce reference dose level taking into account the national 

4400 practice. Radiat Prot Dosimetry 114(1-3):188-91. 

4401 Wagner LK, Archer BR, Cohen AM. 2000. Management of patient skin dose in fluoroscopically 

4402 guided interventional procedures. Journal of Vascular and Interventional Radiology 

4403 11(1):25-33. 

4404 Wall BF. 2001. Diagnostic reference levels--the way forward. Br J Radiol 74(885):785-8. 

4405 Wall BF, Shrimpton PC. 1998. The historical development of reference doses in diagnostic 

4406 radiology. Radiat Prot Dosimetry 80(1-3):15-19. 

4407 Wallace MJ, Kuo MD, Glaiberman C, Binkert CA, Orth RC, Soulez G. 2008. Three4408 Dimensional C-arm Cone-beam CT: Applications in the Interventional Suite. Journal of 

4409 Vascular and Interventional Radiology 19(6):799-813. 

4410 WHO. 2004. WHO Scientific Group on the Assessment of Osteoporosis at Primary Health Care 

4411 Level, Summary meeting report, Brussels, Belgium 5-7 May 2004. Geneva: World 

4412 Health Organization. 

4413 WHO. 2012. WHO fracture risk assessment tool. University of Sheffield, UK World Health 

4414 Organization Collaborating Centre for Metabolic Bone Diseases. 

4415 Willis CE, Slovis TL. 2005. The ALARA concept in pediatric CR and DR: dose reduction in 

4416 pediatric radiographic exams--a white paper conference. AJR. American Journal of 

4417 Roentgenology 184(2):373-4. 

4418 Witzel J. 2008. Operational and radiation safety guidelines for hand held intraoral x-ray systems 

4419 - A thesis. San Antonio, TX: The University of Texas Health Science Center at San 

4420 Antonio. 47 p. 

4421 

4422