Evaluation of Radiation Doses Received by Physicians during Permanent ¹⁹⁸Au Grain Implant Brachytherapy for Oral Cancer

Featured Application: Importance of the evaluation of the physician’s eye exposure to radiation during ¹⁹⁸Au grain brachytherapy, given that the eye dose limit has been reduced drastically from 150 to 20 mSv/year. Brachytherapy is a practical, effective procedure for the local treatment of cancer; it delivers a high radiation dose to a limited tissue volume while sparing the surrounding normal tissues. Although the clinical benefit of brachytherapy is clear, there have been very few studies on the radiation dose received by physicians during the procedure. Furthermore, no study has investigated the eye radiation dose received by physicians performing ¹⁹⁸Au grain (seed) brachytherapy, using an eye dosimeter. Recently, the International Commission on Radiological Protection (ICRP) recommended significantly reducing the occupational lens dose limit, from 150 to 20 mSv/yr (100 mSv/5 years). Therefore, it has become essential to evaluate the eye radiation doses of medical workers. We evaluated the eye radiation dose of a brachytherapy physician performing ¹⁹⁸Au permanent grain implantation for tongue cancer; this is the first study on this topic. The maximum eye dose was ~0.1 mSv/procedure, suggesting that it is unlikely to exceed the ICRP limit (20 mSv/yr) for the lens, unless many procedures are performed with inappropriate radiation protection. To reduce the dose of radiation received by ¹⁹⁸Au grain brachytherapy physicians, it is necessary to use additional lead shielding equipment when preparing the treatment needles, i.e., when loading the grains. This study provides useful information on radiation exposure of physicians conducting ¹⁹⁸Au permanent grain brachytherapy.