Purchase this article with an account.
BV Worgul, D Brenner; The Inverse Dose-Rate Effect and Cataractogenesis . Invest. Ophthalmol. Vis. Sci. 2002;43(13):3599.
Download citation file:
© ARVO (1962-2015); The Authors (2016-present)
Purpose: In previous studies we showed that radiogenic cataracts arising from low doses of fractionated high Linear Energy Transfer (LET) radiation exposure can be worse than the same total dose delivered acutely. This is contrary to the experience following low LET irradiation e.g., x-rays, wherein the overall cataractogenicity of a given dose is significantly reduced when administered in fractions or at low dose-rate. The phenomenon, also described in cell culture systems, is referred to as the inverse dose-rate (IDR) effect. The importance of the observation relates directly to radiation safety guidelines for those exposed to such radiation (e.g. airline crews, reactor workers and astronauts). Also the mechanism of the IDR effect raises issues in relation to current theories of radiation action on normal tissues. Based on the cataract experience a mechanism for the IDR effect was hypothesized. This report is the first to test the lynchpin of that hypothesis which rests on a role for the low LET component of the high LET particle track. Methods: The heads of 4 week old rats were irradiated in groups of eight with 50 cGy of 450 MeV Fe56 ions and/or 2 Gy of 250 kVp X-rays. The eyes were exposed along the Bragg plateau of the ion beam. The X-rays were delivered either three hours prior to, or three hours after, the Fe56 exposure. Following exposure the eyes of the rats were examined by slit-lamp biomicroscopy for the lifespan of the animals or the achievement of bilateral 3+ cataracts whichever came first. Results: Individually both radiations were cataractogenic with the Fe56 being far more effective than the X-rays. When the X-rays preceded the ions the effect was greater in a stage specific way than if administered in the reverse order. Conclusion: The data are consistent with the predication of the IDR effect hypothesis as it applies to radiation cataract development. The importance of the observation is underscored by a recent finding of cataract appearance among the astronaut corps at doses predicted by our rodent experiments. (Cuccinotta et al. In Press, Rad. Res.)
This PDF is available to Subscribers Only