Radiation Dose to the Lens of the Eye in US Navy Medical Workers

Abstract

In 2012, the International Committee for Radiation Protection (ICRP) published a report recommending a change in the allowable lens dose equivalent from 150 mSv per year to 20 mSv per year averaged over five years not to exceed 50 mSv in any one year. This recommendation is based on new research which suggests that radiogenic cataracts may be caused by doses of radiation significantly lower than previously believed. As of this time, there is no current proposed rule by the United States to adopt similar more restrictive dose limits due to lack of research into current doses and potential disruption into existing operations. Previous research into this issue suggests that doses are relatively stable but widely variable due to differences in dosimetry technology, monitoring techniques, radiation safety practices, and technological differences. This thesis used 17 years historical dosimetry data from the Naval Dosimetry Center to analyze the risk of exceeding ICRP’s suggested lens dose equivalent limits in Navy facilities. 4,182 dose reading entries are analyzed and show that although there are minor differences in the mean lens dose equivalent between years, there is no trend of increasing dose over time. Only one individual of 996 exceeded the proposed lower dose limit. Based on the analyses in this thesis, adoption of the proposed dose limits could occur with minimal disruption to current administrative and work practices.