R e s i d e n t s ’ S e c t i o n • P hy s i c s M i n i m o d u l e Frey Radiation Cataracts
Downloaded from www.ajronline.org by Health Sciences Library on 10/26/14 from IP address 129.49.51.170. Copyright ARRS. For personal use only; all rights reserved
Residents’ Section Physics Minimodule
Radiation Cataracts: New Data and New Recommendations G. Donald Frey 1 Frey GD
OBJECTIVE. This Minimodule discusses radiation cataracts and makes some basic suggestions for practicing radiologists. CONCLUSION. For many years radiation-induced cataracts were considered unlikely by most radiologists. Recent data suggest that the likelihood is much higher than previously thought, and the International Commission on Radiological Protection has suggested lower exposure limits.
F
Keywords: radiation cataracts, radiation effects, radiation protection DOI:10.2214/AJR.13.11242 Received May 16, 2013; accepted without revision May 18, 2013. 1
Department of Radiology, Medical University of South Carolina, 171 Ashley Ave, Charleston, SC 29425. Address correspondence to G. D. Frey ([email protected]). WEB This is a web exclusive article. AJR 2014; 203:W345–W346 0361–803X/14/2034–W345 © American Roentgen Ray Society
or many years, it has been known that radiation can cause lens opacities commonly called radiation cataracts [1]. Until recently, it was believed that there was a high threshold for these events, and the radiation protection standards reflected this. The current Nuclear Regulatory Commission (NRC) limit for exposure to the lens of the eye is 150 mSv effective dose per year [2]. This limit was based on the suggestion that the threshold for cataract formation was 2 Gy for a single exposure [3]. Thus, it was commonly believed that patients and radiologists were unlikely to develop radiation cataracts from routine procedures. Eye protection was only considered important for interventional radiologists and cardiologists. In recent years, there have been a number of studies of astronauts [4] and interventional cardiologists [5, 6] that suggest that the radiation dose that can cause the formation of a radiation cataract is much lower than previously thought. International Commission on Radiological Protection Recommendations These studies have led the International Commission on Radiological Protection (ICRP) to issue two new recommendations [7]. The first is that the threshold now be considered to be 500 mGy, which is about four times lower than previously thought. The second is that the annual dose limit should be set at an average of 20 mSv per year, with
no year exceeding 50 mSv. The current NRC limit is 7.5 times higher. It should be noted that these values have not been adopted by the NRC in the United States. Therefore, these recommendations are advisory rather than regulatory. Recommendations for Radiologists In light of the ICRP recommendations, it would be prudent for radiologists to undertake a few steps. Radiologists should review their radiation badge readings to see whether their annual doses are exceeding 20 mSv/y. This is shown on the badge report as eye dose equivalent. If the dose is close to or above the 20-mSv value, steps should be taken to reduce the exposure. Some common steps to reduce exposure are to spend more time behind a shield that protects the eyes or to wear specific eye protection. There has been a recent review of eye protection [8]. Because radiation cataracts begin to form on the posterior pole of the lens, radiologists should inform their ophthalmologists that they are exposed to radiation to ensure that the posterior pole is examined. References 1. Merriam GR Jr, Foct EF. A clinical study of radiation cataracts and their relation to dose. Am J Roentgenol Rad Ther Nucl Med 1957; 77:759– 785 2. U.S. Nuclear Regulatory Commission. Guide for the preparation of applications for use of sealed sources and devices for performing industrial radiography: regulatory guide 10.6, revision 1.
AJR:203, October 2014 W345
Downloaded from www.ajronline.org by Health Sciences Library on 10/26/14 from IP address 129.49.51.170. Copyright ARRS. For personal use only; all rights reserved
Frey Code of Federal Regulation 10 CFR 20.1201.2.i. December 1981 3. International Commission on Radiological Protection (IRCP) website. Annals of the ICRP: the 2007 recommendations of the International Commission on Radiological Protection, publication 103. www. icrp.org/docs/ICRP_Publication_103-Annals_of_ the_ICRP_37%282-4%29-Free_extract.pdf. Accessed June 19, 2014 4. Cucinotta FA, Manuel FK, Jones J, et al. Space
W346
radiation and cataracts in astronauts. Radiat Res 2001; 156:460–466 5. Ciraj-Bjelac O, Rehani M, Minamoto A, et al. Radiatio-induced eye lens changes and the risk for cataract in interventional cardiology. Cardiology 2012; 123:168–171 6. Jacob S, Boveda S, Bar O, et al. Interventional cardiologists and the risk of radiation-induced cataract: results of a French multicenter observational study. Int J Cardiol 2013; 167:1843–1847
7. International Commission on Radiological Protection (ICRP). ICRP statement on tissue reactions/early and late effects of radiation in normal tissues and organs: threshold doses for tissue reactions in a radiation protection context. ICRP publication 118. Ann ICRP 2012; 41:1–2 8. Struchio GM, Newcomb RD, Moletta R, Varkey P, Hagen PT, Schueler BA. Protective eyewear selection for interventional fluoroscopy. Health Phys 2013; 104(2 suppl 1):S11–S16
AJR:203, October 2014
Downloaded from www.ajronline.org by Health Sciences Library on 10/26/14 from IP address 129.49.51.170. Copyright ARRS. For personal use only; all rights reserved
Residents’ Section Physics Minimodule
Radiation Cataracts: New Data and New Recommendations G. Donald Frey 1 Frey GD
OBJECTIVE. This Minimodule discusses radiation cataracts and makes some basic suggestions for practicing radiologists. CONCLUSION. For many years radiation-induced cataracts were considered unlikely by most radiologists. Recent data suggest that the likelihood is much higher than previously thought, and the International Commission on Radiological Protection has suggested lower exposure limits.
F
Keywords: radiation cataracts, radiation effects, radiation protection DOI:10.2214/AJR.13.11242 Received May 16, 2013; accepted without revision May 18, 2013. 1
Department of Radiology, Medical University of South Carolina, 171 Ashley Ave, Charleston, SC 29425. Address correspondence to G. D. Frey ([email protected]). WEB This is a web exclusive article. AJR 2014; 203:W345–W346 0361–803X/14/2034–W345 © American Roentgen Ray Society
or many years, it has been known that radiation can cause lens opacities commonly called radiation cataracts [1]. Until recently, it was believed that there was a high threshold for these events, and the radiation protection standards reflected this. The current Nuclear Regulatory Commission (NRC) limit for exposure to the lens of the eye is 150 mSv effective dose per year [2]. This limit was based on the suggestion that the threshold for cataract formation was 2 Gy for a single exposure [3]. Thus, it was commonly believed that patients and radiologists were unlikely to develop radiation cataracts from routine procedures. Eye protection was only considered important for interventional radiologists and cardiologists. In recent years, there have been a number of studies of astronauts [4] and interventional cardiologists [5, 6] that suggest that the radiation dose that can cause the formation of a radiation cataract is much lower than previously thought. International Commission on Radiological Protection Recommendations These studies have led the International Commission on Radiological Protection (ICRP) to issue two new recommendations [7]. The first is that the threshold now be considered to be 500 mGy, which is about four times lower than previously thought. The second is that the annual dose limit should be set at an average of 20 mSv per year, with
no year exceeding 50 mSv. The current NRC limit is 7.5 times higher. It should be noted that these values have not been adopted by the NRC in the United States. Therefore, these recommendations are advisory rather than regulatory. Recommendations for Radiologists In light of the ICRP recommendations, it would be prudent for radiologists to undertake a few steps. Radiologists should review their radiation badge readings to see whether their annual doses are exceeding 20 mSv/y. This is shown on the badge report as eye dose equivalent. If the dose is close to or above the 20-mSv value, steps should be taken to reduce the exposure. Some common steps to reduce exposure are to spend more time behind a shield that protects the eyes or to wear specific eye protection. There has been a recent review of eye protection [8]. Because radiation cataracts begin to form on the posterior pole of the lens, radiologists should inform their ophthalmologists that they are exposed to radiation to ensure that the posterior pole is examined. References 1. Merriam GR Jr, Foct EF. A clinical study of radiation cataracts and their relation to dose. Am J Roentgenol Rad Ther Nucl Med 1957; 77:759– 785 2. U.S. Nuclear Regulatory Commission. Guide for the preparation of applications for use of sealed sources and devices for performing industrial radiography: regulatory guide 10.6, revision 1.
AJR:203, October 2014 W345
Downloaded from www.ajronline.org by Health Sciences Library on 10/26/14 from IP address 129.49.51.170. Copyright ARRS. For personal use only; all rights reserved
Frey Code of Federal Regulation 10 CFR 20.1201.2.i. December 1981 3. International Commission on Radiological Protection (IRCP) website. Annals of the ICRP: the 2007 recommendations of the International Commission on Radiological Protection, publication 103. www. icrp.org/docs/ICRP_Publication_103-Annals_of_ the_ICRP_37%282-4%29-Free_extract.pdf. Accessed June 19, 2014 4. Cucinotta FA, Manuel FK, Jones J, et al. Space
W346
radiation and cataracts in astronauts. Radiat Res 2001; 156:460–466 5. Ciraj-Bjelac O, Rehani M, Minamoto A, et al. Radiatio-induced eye lens changes and the risk for cataract in interventional cardiology. Cardiology 2012; 123:168–171 6. Jacob S, Boveda S, Bar O, et al. Interventional cardiologists and the risk of radiation-induced cataract: results of a French multicenter observational study. Int J Cardiol 2013; 167:1843–1847
7. International Commission on Radiological Protection (ICRP). ICRP statement on tissue reactions/early and late effects of radiation in normal tissues and organs: threshold doses for tissue reactions in a radiation protection context. ICRP publication 118. Ann ICRP 2012; 41:1–2 8. Struchio GM, Newcomb RD, Moletta R, Varkey P, Hagen PT, Schueler BA. Protective eyewear selection for interventional fluoroscopy. Health Phys 2013; 104(2 suppl 1):S11–S16
AJR:203, October 2014
