A Reanalysis of Atomic-Bomb Cataract Data, 2000???2002: A Threshold Analysis

Abstract

To obtain the best statistical model for a previous study of cataract prevalence in atomic-bomb survivors, we tested the fitness of the threshold model in an updated dataset of the study, utilizing re-diagnosis by a single ophthalmologist, use of the DS02 dosimetry system, and separation of the in utero group. The results suggest that, in 730 atomic-bomb survivors, we cannot conclude thresholds are greater than 0 Sv in cortical cataract and posterior sub-capsular opacity since the lower 90% confidence limits of the thresholds were 0 Sv. Threshold dose point estimates were 0.6 Sv (90% CI, <0.0-1.2 Sv) and 0.7 Sv (90% CI, <0.0-2.8 Sv) for cortical cataract and posterior sub-capsular opacity, respectively. Detailed regression analyses with no threshold model showed that nuclear color and nuclear opacity have no dose responses (p > 0.40). Cortical cataract showed a significant dose effect (p = 0.002), with an odds ratio (OR)/Sv of 1.30 (95% CI, 1.10-1.53) and no dose-effect modifiers. Posterior sub-capsular opacity showed a significant dose effect (p < 0.001), with an OR/Sv of 1.44 at age of exposure of 10 y (95% CI, 1.19-1.73). The dose effect decreased significantly with increasing age at exposure (p = 0.022). No dose response was observed for in utero survivors (p > 0.20).

Evaluation of a Suspended Personal Radiation Protection System vs. Conventional Apron and Shields in Clinical Interventional Procedures

“…The growth in utilization and complexity of fluoroscopic procedures has increased workload for interventionalists, resulting in cumulative radiation doses and orthopedic strains that can be limiting or career ending [1][2][3][4][5][6][7][8][9][10][11]. Despite suffering significantly increased neck and back pain, lost work time, and cervical disc herniations (P < 0.01) [4], exposures remain excessive as demonstrated by one operator receiving the equivalent of 60 skull films during 1 month's practice using available shielding [12].…”

Ionizing Radiation as a Risk Factor for Cataract: What about Low-Dose Effects?

“…In contrast, Minamoto's study [14] used a standardized classification to grade cataract and each type of lens opacity was separated during the statistical analysis. In Nakashima's study [15] they also separated the different types of lens opacities. Moreover, the fact that a single ophthalmologist reviewed all the diagnoses is one of the study's strong suits.…”

“…Indeed Nakashima et al found that the threshold dose for cortical and posterior subcaspular cataract was 0.6 and 0.7 Sv respectively, yet neither was statistically different from 0, which led them to wonder whether there was indeed a threshold or not [15]. In any case, if that threshold does exist several arguments seem to indicate that it would probably be under 1 Gy: Worgul reports a significant threshold of 0.35 Gy for posterior sub-capsular cataracts (CI95% = [0.19; 0.66]), which is much lower than the traditional 2 Gy [12].…”

“…Nakashima et al [15] then reanalyzed Minamoto's data to try and establish threshold radiation doses for cortical and posterior subcapsular opacities since they were the only ones for which the dose main effects were significant. They used the same subjects as in the previous study, focusing on the 730 who had been exposed after birth and separating them from the 143 who had been exposed in utero.…”

Monitoring of eye lens doses in radiation protection

“…The two main reasons for this keen interest were the results of epidemiological studies, for instance for workers in the medical sector, which showed the existence of cases of cataracts for doses lower than 0.5 Gy (Nakashima et al, 2006;Worgul et al, 2007;Chodick et al, 2008), and subsequently the recommendation by the ICRP to decrease the exposure limit for workers from 150 mSv per year to 20 mSv in a year averaged over defined periods of five consecutive years, with no single year exceeding 50 mSv (ICRP, 2011). These recommendations are introduced in the European directive 2013/59 (EURATOM, 2013).…”