Radiation-induced cataracts: the Health Protection Agency’s response to the ICRP statement on tissue reactions and recommendation on the dose limit for the eye lens

Abstract

This paper presents the response of the Health Protection Agency (HPA) to the 2011 statement from the International Commission on Radiological Protection (ICRP) on tissue reactions and recommendation of a reduced dose limit for the lens of the eye. The response takes the form of a brief review of the most recent epidemiological and mechanistic evidence. This is presented together with a discussion of dose limits in the context of the related risk and the current status of eye dosimetry, which is relevant for implementation of the limits. It is concluded that although further work is desirable to quantify better the risk at low doses and following protracted exposures, along with research into the mechanistic basis for radiation cataractogenesis to inform selection of risk projection models, the HPA endorses the conclusion reached by the ICRP in their 2011 statement that the equivalent dose limit for the lens of the eye should be reduced from 150 to 20 mSv per year, averaged over a five year period, with no year's dose exceeding 50 mSv.

The value of protective head cap and glasses in neurointerventional radiology

“…Moreover, a number of studies have suggested that there may be a substantial risk of lens opacities in populations exposed to low doses of ionizing radiation; these include patients undergoing CT scans,17 astronauts,18 radiological technologists/radiographers,19 atomic bomb survivors,20 and those exposed in the Chernobyl accident 21. Therefore, the International Commission of Radiological Protection has proposed that the occupational dose limit for the eye lens should be reduced from 150 to 20 mSv, averaged over a defined period of 5 years, with no single year exceeding 50 mSv 22. Regarding exposed skin, the short term risk to patients is radiation induced skin damage, which can result from acute radiation doses of 2 Gy.…”

The lens of the eye: exposures in the UK medical sector and mechanistic studies of radiation effects

“…These studies have been considered in recent reviews (Ainsbury et al, 2009;Bouffler et al, 2012) which also concluded that the absorbed dose threshold for cataract is around 0.5 Gy in the case of acute exposures, with protraction or fractionation of exposure having little effect on the value. A particularly important study is that of Neriishi et al (2007), which reports on the prevalence of cataracts requiring surgical intervention among atomic bomb survivors.…”

“…In considering potential mechanisms of radiation-associated lens cataract, Bouffler et al (2012) observed that the dose-response slope for cataract and lens opacities reported in the more recent epidemiological investigations is not as steep as conventionally considered to apply to tissue reactions, and several studies have indicated that incidence can be described by a non-threshold dose-response relationship. This suggests that effects on the lens of the eye may be governed by processes other than cell killing or functional inactivation, as generally accepted to be important for the induction of tissue reactions.…”

Radiation exposure and safety practices during pediatric central line placement

“…Occupational radiation-related dose-response epidemiological data are lacking for physicians and technologists performing fluoroscopically guided procedures [14]. Recent cohort studies have found increasing evidence of deterministic effects of radiation causing lens opacities at a lower dose than initially suspected [15]. A study of 69 nurses and 58 interventional cardiologists, with an estimated cumulative eye dose range of 0.1 to 18.9 Sv (from survey), demonstrated posterior subcapsular lens changes consistent with ionizing radiation exposure in 50% of physicians and 41% of nurses and technicians compared to 10% seen in age-matched controls [16].…”