Determination of a reliable assessment of radiation doses to the eye lens in nuclear medicine

3050 Purpose: The most recently published ICRP statement describes a reduction in the maximum allowable radiation dose to the eye lens to 20, from 150 mSv/year. Exposure of the eye lens to radiation is a concern for nuclear medicine staff who handle radionuclide tracers with elevated levels of γ energy. The present study aimed to determine an optimal means of measuring the amount of radiation to which the eye lens is exposed in nuclear medicine. Methods: An anthropomorphic phantom with VISION, DOSIRIS, nanoDot, RPL and OSL dosimeters attached to the eye, neck, chest and abdomen was exposed to 99mTc, 123I and 18F tracers. Each radionuclide was positioned at 30 cm from the abdomen of the phantom. The amounts of exposure to each radionuclide were compared among the dosimeters. Results: The values of each dosimeter were underestimated at the neck by a maximum of 65% compared with the chest or abdomen. Measured values between RPL and OSL differed according to the type of SPECT or PET radionuclide. In contrast, the eye lens dosimeter indicated a photon energy-independent tendency. Conclusions: Radiation doses to the eye lenses of nuclear medicine staff are conventionally monitored by personal dosimeters worn around the chest or abdomen. However, the present findings indicated that eye dosimeters would be more appropriate.