Demonstrating Compliance With Proposed Reduced Lens of Eye Dose Limits in Nuclear Medicine Settings

Based on ongoing research on ionizing radiation thresholds for cataracts, the International Commission on Radiological Protection has proposed new guidelines lowering the annual occupational lens of eye dose limit from 150 mSv to 20 mSv. The International Atomic Energy Agency has operationalized these new guidelines. Subsequently, national/regional radiation protection regulators are reviewing their lens of eye dose limits with an aim of moving towards the proposed new limits, resulting in licensees having to demonstrate compliance. In health care settings, fluoroscopic interventional practices generally have higher lens of eye doses and nuclear medicine settings generally have lower doses. A prospective cohort (n = 19) of nuclear medicine technologists wore dedicated lens of eye dosimeters for a 3 mo period synchronized with their body dosimeter schedules. The lens of eye dosimeters were validated to have a linear response in the anticipated dose ranges. The participants worked in a relatively high-volume nuclear medicine practice, which included general and cardiac, positron emission tomography/computed tomography, radiopharmacy, and cyclotron operations. The annualized dose ranges were 0.0-3.68 mSv (lens of eye) and 0.48-4.72 mSv (whole body). There was a good correlation between lens of eye and body dosimeter readings (R = 0.67). There were no significant differences in lens of eye dose by work type, worker sex, or side on which the dosimeter was worn. The findings should be generalizable to other similar practices, especially in North America, and should be sufficient to demonstrate regulatory compliance in nuclear medicine settings with the proposed new lens of eye dose limits.