Madan Rehani, PhD. Radiation & Cataract: A New Challenge. What is cataract? Cataract

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1 What is cataract? Radiation & Cataract: A New Challenge Madan Rehani, PhD Radiation Protection of Patients Unit, IAEA, Vienna, Austria Lawrence Dauer, PhD Medical Physics, Memorial Sloan-Kettering Cancer Center M.Rehani@iaea.org Clouding or opacification of the natural lens of the eye and obstructing the passage of light Rehani & Dauer AAPM/COMP Cataract Lenticular Opacification Risk Factors: Corticosteroids Diabetes Mellitus Sunlight exposure (UVB) Trauma Infections Nutritional deprivation Age (~ 50% >65 yrs) Heredity Radiation Rehani & Dauer AAPM/COMP 2011 Rehani & Dauer AAPM/COMP

2 What is treatment? Phacoemulsification Easily treatable condition -surgery Eye's internal lens is emulsified with an ultrasonic handpiece Aspirated from the eye. Aspirated fluids replaced with irrigation of balanced salt solution Nothing to match natural Rehani & Dauer AAPM/COMP Rehani & Dauer AAPM/COMP Radiation & Cataract Dot Opacities Latency depends on rate at which damaged epithelial cells undergo fibrogenesis and accumulate. HOT Topic in Occupational Radiation Protection Rehani & Dauer AAPM/COMP Rehani & Dauer AAPM/COMP

3 Unlike Patients where.. Rehani & Dauer AAPM/COMP Rehani & Dauer AAPM/COMP Epithelium Capsule Epithelium nucleus CORNEA ANTERIOR CHAMBER LENS PSC Cataract Capsule a. b. 3

4 Major Cataract Subtypes Cortical Nuclear Posterior SubCapsular (psc) Mixed Rehani & Dauer AAPM/COMP Rehani & Dauer AAPM/COMP History of radiation cataract Documented within 1 year of Roentgen s discovery of X rays H. Chalupecky, Ueber die wirkung der Roentgenstrahlen. Centralblatt fuer praktische Augenheilkunde (J. Hirschberg Ed.), pp Veit, Leipzig, History of radiation cataract-ii However, cataract was long thought to result from only high doses of radiation to the lens of the eye. This was based on data from early cyclotron workers with cataract after substantial neutron doses and with early Japanese A-bomb studies that reported excess cataracts among those who received over 2 3 Gy. Rehani & Dauer AAPM/COMP Rehani & Dauer AAPM/COMP

5 Up to early 1950 s W. Rohrschneider, Beitrag zur entstehung und morphologie der ro ntgenstrahlenkatarakt. Klin. Monatsbl. Augenheilkd. 81, (1928). A. U. Desjardins, Action of Roentgen rays and radium on the eye and ear. Am. J. Roentgenol. 26, (1931). P. J. Leinfelder and H. D. Kerr, Roentgen-ray cataract: An experimental, clinical, and microscopic study. Am. J. Ophthalmol. 19, (1936). D. G. Cogan and K. K. Dreisler, Minimal amount of x- ray exposure causing lens opacities in the human eye. AMA Arch. Ophthalmol. 50, (1953). Rehani & Dauer AAPM/COMP Rehani & Dauer AAPM/COMP Beliefs based on data in late 1950 s G. R. Merriam and E. Focht, A clinical study of radiation cataracts and the relationship to dose. Am. J. Roentgenol. Radium Ther. Nucl. Med. 77, (1957). G. R. Merriam and E. F. Focht, A clinical and experimental study of the effect of single and divided doses of radiation on cataract production. Trans. Am. Ophthalmol. Soc. 60, (1962). Cataract has a dose threshold The severity increased and the latency decreased as the radiation dose increased above that threshold Latent period was strongly inversely correlated with dose and that there was no cataract induction below 2 Gy. Rehani & Dauer AAPM/COMP Rehani & Dauer AAPM/COMP

6 Other major papers that influenced ICRP 60 and 103 M. D. Nefzger, R. J. Miller and T. Fujino, Eye findings in atomic bomb survivors of Hiroshima and Nagasaki: Am. J.Epidemiol. 89, (1969). M. Otake and W. Schull, Radiation-related posterior lenticular opacities in Hiroshima and Nagasaki atomic bomb survivors based on the DS86 dosimetry system. Radiat. Res. 121, 3 13 (1990). Rehani & Dauer AAPM/COMP Rehani & Dauer AAPM/COMP NCRP Visually disabling cataracts of 2 10 Sv for single brief exposures, and 0.8 Sv for protracted exposures However, new data on the radiosensitivity of the eye with regard to visual impairment are expected. Rehani & Dauer AAPM/COMP 2011 Rehani & Dauer AAPM/COMP

7 What is New? Lens opacities being reported at dose levels below the currently mentioned threshold in ICRP, NCRP Odds Ratio Is a measure of effect size, describing the strength of association or non-independence between two binary data values. Odds ratio treats the two variables being compared symmetrically, and can be estimated using some types of non-random samples Ratio of the odds of an event occurring in one group to the odds of it occurring in another group Rehani & Dauer AAPM/COMP Rehani & Dauer AAPM/COMP Neriishi et al, Rad Research 168:2007 Operative Cataract odds ratio of ~1.4 at 1 Gy Dose threshold seen at 0.1 Gy (upper bound of 0.8 Gy). A-Bomb Survivors A-Bomb Survivors Minamoto et al, Int. J Rad Biol 80(5):2004 Prevalence of cortical and posterior subcapsular opacities showed significant correlation with radiation dose Odds ratios of ~1.3 at 1 Gy Rehani & Dauer AAPM/COMP Rehani & Dauer AAPM/COMP

8 Chernobyl Airline Pilots Worgul et al, Rad Research 167:2007 Dose effect threshold < 1 Gy UN Chernobyl Forum 2006 Even low doses of 0.25 Gy may also be cataractogenic. Rafnsson et al, Arch Ophthalmol. 123:2005 Cosmic radiation may be a causative factor in nuclear cataracts. Note some have disagreed with this assertion Rehani & Dauer AAPM/COMP Rehani & Dauer AAPM/COMP Aviators / Astronauts Astronauts Jones et al, Aviat Space Environ Med 78:2007 Military aviators with cataracts were found to have a younger average age at onset compared with astronauts. Prevalence of cataracts was found to be higher in astronauts than aviators. Cucinotta Rehani & Dauer AAPM/COMP Rehani & Dauer AAPM/COMP

9 Astronauts Infancy Exposures Cucinotta et al, Rad Research 156:2001 Relatively low doses of space radiation are causative of an increased incidence and early appearance of cataracts Increased risk with higher lens doses > 8 msv Hall et al, Rad Research 152:1999 Children exposed to lenticular doses during skin hemangioma treatments Odds ratio for developing posterior subcapsular cataract 1.5 at 1 Gy Odds ratio for developing cortical opacity 1.35 at 1 Gy Rehani & Dauer AAPM/COMP Rehani & Dauer AAPM/COMP Chronic Low Dose Exposures Interventional Radiologists Chen et al, Rad Research 156:2001 Contaminated buildings in Taiwan Minor lenticular changes in lenses of young subjects Haskal & Worgul, RSNA News 2004:14 Radiologists 5/59 posterior subcapsular cataracts 22/59 small dot-like opacities (early signs of radiation damage) 1/59 had undergone cataract surgery in one eye Rehani & Dauer AAPM/COMP Rehani & Dauer AAPM/COMP Schueller et al, Radiographics

10 Strength of newer studies over earlier ones Inspection of the Merriam and Focht papers shows that the observation periods after irradiation were mostly quite short (average of 8 years) They studied only 20 individuals who had estimated lens doses under 2 Gy, Negative aspects of earlier studies: short follow-up periods, failed to take into account increasing latent periods with decreasing doses, relatively few subjects with doses below a few Gy. Positive aspects of newer studies: Long followup, larger numbers, lower doses Rehani & Dauer AAPM/COMP Rehani & Dauer AAPM/COMP Why longer follow-up? The latent period is dependent on the rate at which damaged epithelial cells undergo aberrant differentiation (fibergenesis) and accumulate in the PSC region of the lens cortex. Rehani & Dauer AAPM/COMP Rehani & Dauer AAPM/COMP

11 Active collaborators IAEA Cataract Eliseo Vano Norman Kleiman A Minanoto Ariel Duran KH Sim Olivera Ciraj Raul Ramirez A Nader Plus a team of Rehani local & Dauer ophthalmologists AAPM/COMP Rehani & Dauer AAPM/COMP Objective To examine the prevalence of radiationassociated lens opacities among interventional cardiologists and technical staff and correlate with occupational radiation exposure Not purely a doismetry or effect study Dose and effect Background Since we are concerned with determination of effect, we need doses incurred in past, not prospective Non-availability of records of measured values from routine individual monitoring Non-availability of widely accepted methods for retrospective estimation Rehani & Dauer AAPM/COMP Rehani & Dauer AAPM/COMP

12 Interventional procedures Limited occupational dose data, USA/Canada?? 20-30% of cardiologists do not use dosimeter routinely (Vano et al, BJR, 2006, 79: ) In developing countries 40-90% Errors in use of dosimeters: Identification Interchange Use of protective devices?? Vano et al, Radiology, 2008: Rehani & Dauer AAPM/COMP Rehani & Dauer AAPM/COMP Dose information for various studies (I) Model Value Unit Source Remark n/a 59 µsv/proc Tsapaki ate all, PMB, 2004 CA, 5 countries, shoulder dose n/a 89 µsv/proc Tsapaki ate all, PMB, 2004 PTCA, 5 countries, Shoulder dose Philips Optimus M 260 msv/y Vano, et al, BJR, procedure/y 200 Poly C Philips 31 msv/y Vano, et al, BJR, procedure/y Integris HM 300 Philips 18 msv/y Vano, et al, BJR, procedure/y Integrtis N-5000 Philips 3.5 msv Kuipers et al, Cardiovas Int 4 weeks, TLD above the Integrtis Allura Rad, 2008 apron Philps msv/proc Steffino, et al BJR 1996 Ceiling screen in place Polydiagnost C2 Not available 0.11 msv/proc Pratt and Shaw, BJR, 1993 Ceiling screen and Goggles in place CGR DG msv/proc Marshall et al, BJR 1995 Eye dose, lead shield Siemens 0.28 msv/proc Calkins et al, circulations, Eye, Ceiling screen in place Angioskop D 1991 Philips Alura Table 1 Sv//h Vano et al. Radiology Dose rate at 1 m. h=1.6 m 10FD/20FD. GE for different modes (fluoro. Advantix, Philips cine..) Intergris 3000/5000, Rehani & Dauer AAPM/COMP Siemens Axiom bip A Dose information for various studies (II) Model Value Unit Source Remark Kuipers et al, J TLD dose above the apron, mean value for 7 Philips Integris Allura 3.85 msv/4 weeks Inte Card, 2008 radiologists Average 35 institutions 48 msv/y Niklason at al, 972 procedures/y, dose above the apron Radiolgy, 1993 Philips Integris 3000, II Williams, BJR, 6.55 msv/month 46 procedures/month, neck dose GE L-U, II 1997 Not available Figure 2.b µgy/min Whitby, et al, PTCA BJR, 2005 Different types of systems, 0.5 (IC) Vano et al, BJR, msv/proc Without protective tools average values 0.15 (nurses) 1998 Philips Integris V 3000 Figs 3.4,6,7 µgy/min Whitby, BJR, Diagrams for PA, RAO, LAO projections 2003 Different units Table 3 µ Sv/proc Vano, et al, BJR, TLD dose, eyes, with and without protective screen 1998 Figs Morrish et al Scatter dose rate for fluoroscopy and acquisition for Philips Integris HM 3000 µgy/min 11 BJR, 2008 different projections Rehani & Dauer AAPM/COMP

13 Remarks Reported eye lens doses: mgy/study (without use of protective devices) mgy/study (with protective devices) Multiple dosimetry quantities: air kerma, H*(10), Hp(10), Hp(3) ) Inaccuracy in dose assessment for nurses due to large variability of location and multiple tasks performed Our Decision Typical doses if protective devices are not used 0.5 mgy/procedure for interventional cardiologists 0.15 mgy/procedure for and nurse This exposure corresponds to a typical procedure of 10 min of fluoroscopy and 800 cine frames Rehani & Dauer AAPM/COMP Rehani & Dauer AAPM/COMP Radiation dose assessment Materials and methods Typical doses if protective devices are not used: 0.5 mgy/procedure for interventional cardiologists 0.15 mgy/procedure for and nurse Interventional cardiologists and nurses Control group Workload: number of procedures per week fluoroscopy time number of cine series per procedure number of frames per series Use of protective devices: ceiling suspended screens (factor: 0.1) leaded glass eyewear (factor: 0.1) Angulations (factor: 1.8) Radial access (factor: 2.0) Rehani & Dauer AAPM/COMP Rehani & Dauer AAPM/COMP

14 Dose related parameters (I) Dose related parameters (II) Parameter Number of years in interventional cardiology Model of fluoroscopy system used (in the past/now) Use of ceiling suspended screens (in % of time period), S Use of goggles (in % of time period), G Workload: number of procedures/week Fluoroscopy time/procedure No of frames/procedure (no of frames/series and series/ procedure) Source form form form form form form form Parameter Source Value Factor Attenuation of goggles, A literature 90% Attenuation of ceiling suspended screen, B literature 90% Distance from isocenter literature 75 cm ISL For particular procedure. for different models of interventional systems at eye level scatter dose: Dose rate [Sv/h] Normalized dose rate [Sv/mAs] Total dose for typical procedure [Sv/study] Angulations Radial access literature; different sources to match the model of the system literature: Vano, 2006 Batsou, 1998 Morrish, 2008 literature: IAEA, 2004 Vano, G S (1 100 (1 100 A) B ) Rehani & Dauer AAPM/COMP Rehani & Dauer AAPM/COMP Scenario Information about model of the unit, workload and typical procedure parameters are available Information about model and workload is available (procedure parameters are not available) Dose assessment Calculation Scattered dose rate Correction for distance, use of protective devices, angulation, radial access Dose ate eye level for typical procedure Annual dose/dose for the whole period use of a particular system Typical exposure parameters from the literature for a particular or similar type if system (10 min fluoroscopy time and 800 cine frames) Same a previous Angulation for typical procedure (CA) Betsou et al. BJR, 1998 Vano et al. Radiology, Average PROJECTION TIME (%) msv/h msv/h PA PA CD PA CR RAO RAO CD RAO CR LAO LAO CD LAO CR L LAT Rehani & Dauer AAPM/COMP Rehani & Dauer AAPM/COMP

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16 Assessment of lens change Dilatated slit lamp examination Merriam-Focht scoring system Scores: Scores >2.0 correlate with visual acuity Rehani & Dauer AAPM/COMP Rehani & Dauer AAPM/COMP Results Rehani & Dauer AAPM/COMP Rehani & Dauer AAPM/COMP

17 PSC changes (score > 0.5) CCI has the highest impact factor of all journals focusing on interventional/invasive therapies. IF 2.5 Interventional cardiologists: Prevalence 52% (29/56. 95% CI: 35-73) Significance (Fisher exact test): p<0.001 Relative risk: 5.7 (95% CI: ) Nurses: Prevalence 45% (5/11. 95% CI: ) Significance (Fisher exact test): p<0.05 Relative risk: 5.0 (95% CI: ) Rehani & Dauer AAPM/COMP Rehani & Dauer AAPM/COMP Subjects Interventional cardiologists Subjects and cumulative radiation dose to the lens of the eye No 56 Age* (y) 42 ± 7 (31-64) No of years in interventional cardiology 9.2 ± 6.9 (1.0-33) Cumulative dose to the lens (Gy)* 3.7 ± 7.5 ( ) Dose response for posterior lens changes in cardiologists and nurses and associated odds ratios (OR). relative risk (RR) and 95% confidence intervals (CI) Dose (Gy) Number of subjects Number of subjects with posterior lens changes* OR 95% CI RR 95% CI 0 (Control) 22 2 (9%) 1.0 n/a 1.0 n/a < (39%) Nurses ± 11 (25-53) 6.0 ± 4.6 (1.0-14) 1.8 ± 3.1 ( ) 1< (45%) <3 9 5 (55%) Control group ± 9 (29-57) n/a n/a (75%) (51%) *mean ± standard Rehani & Dauer deviation; AAPM/COMP values 2011in parentheses are ranges 67 *cataract grade 0.5 or higher in one eye Rehani & Dauer AAPM/COMP

18 Number of interventional cardiologists with posterior lens changes graded by severity of lens changes with associated cumulative doses to the lens of the eye Score N (%) Dose (Gy) mean median min max 0 in both eyes in one eye in both eyes >1 in one eye (0.5 or more in the other eye) Rehani & Dauer AAPM/COMP Rehani & Dauer AAPM/COMP Vano, E., Kleiman, N.J., Duran, A, Rehani MM, D Echeverrie, M Cabreraf. Radiation cataract risk in interventional cardiology personnel. Radiat. Res. 174, (2010). IF exposed individuals and 93 similarly aged non-exposed controls Relative risk of psc opacities in IC was 3.2 (38% compared to 12%; p<0.005). 21% of nurses and technicians Cumulative median values of lens doses were estimated at 6.0 Sv for cardiologists and 1.5 Sv for associated medical personnel. Rehani & Dauer AAPM/COMP Rehani & Dauer AAPM/COMP

19 Conclusions from IAEA studies Threshold value, if any, is much lower that current guidelines indicate Dose-response relationship between occupational exposure and the prevalence of radiation-associated posterior lens changes There is a need to find better means for eye lens dosimetry First ever report among this group Limitations Opacities that had not progressed to cause significant visual disability Preliminary investigation of the dose response relationship A study of a larger cohort is needed Rehani & Dauer AAPM/COMP Rehani & Dauer AAPM/COMP Shielding & Positioning Use Barrier Shielding for Body and Eye Protection Be aware of Staff Location Lens of the eye, threshold in absorbed dose is now considered to be 0.5 Gy (against 0.5 to 2 for detectable opacities and 5 for visual impairment). Occupational Exposure Lens of Eye Limit 20 msv in a y (against 150), averaged over defined periods of 5 y, with no single y exceeding 50 msv Rehani & Dauer AAPM/COMP Rehani & Dauer AAPM/COMP

20 LDE (msv) Shielding & Positioning Eye Shielding Imperative Leaded Ceiling Shield 98% reduction. Leaded Glasses Shield ~74-91% Differences in performance related to operator position, likely representing interplay of design and fit. Sports wraparound or side shields important. Rehani & Dauer AAPM/COMP Rehani & Dauer AAPM/COMP Training & Self-Evaluations Operators and Staff should be trained in the machine operation and radiation protection. Free Training Programs: IAEA has free training program AdditionalResources/Training/1_TrainingMaterial/Radiology.htm MARTIR (Multimedia and Audiovisual Radiation Protection Training in Interventional Radiology) Perform frequent Self-Evaluations / Audits Mitigation Efforts (Training, Behavior Modification & Shielding) ~45% drop in 3 years Lieto and Jackson, Average IR LDE by Year Years Dauer, 2008 Rehani & Dauer AAPM/COMP Rehani & Dauer AAPM/COMP

21 Additional Resources Additional Resources CVIR-JVIR, = IAEA Radiation Protection of Patients gy/lectures/rpdir-l16.2_fluoroscopy_doses_web.ppt Rehani & Dauer AAPM/COMP Rehani & Dauer AAPM/COMP Learning Objectives 1. To understand the basic information about radiation cataractogenesis 2. To understand the efficacy of protective tools 3. To become aware about the most recent changes in recommendation by the ICRP on reduction in eye lend dose limit d IAEA Rehani & Dauer AAPM/COMP Rehani & Dauer AAPM/COMP

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