Radiation Emission from Patients Treated with Holmium-166 Radioembolization

Purpose: To a sess the radiation, exposure to individuals coining from patients-after treatment With holmium-166 (166110) mitrospheres. Materials and methods: Holmium-166 radioembolization(RE) with escalating whole-Ever doses of 20 Gy, 40 Gy, 610 Gy, and 80 Gy was administered to 1-5 patients. Exposure rates,(mu Sv/h) from patients, were measured at 1.0 m distance from a lateral and frontal position at 0, 3, 6, 24, and 48 hours after infusion. The total effective dose equivalent (TEDE) to a maximally exposed contact was calculated in accordance with-guidelines of the U.S. Nuclear Regulatory Commission (NRC). Results were extrapolated to a-Whole-liver dose of 60 Gy used in future treatments. Results: The median exposure rate at discharge, 48 hours after infusion, measured from a lateral position was 26 mu Sv/h (range, 7-45 mu Sv/h). Extrapolated to a whole-liver dose of 60 Gy, none of the exposure rates for the NRC contact scenario, at any-time, frontal or lateral, would lead to a TEDE > 5 mSv; all patients may be released directly after treatment. Release after 6 hours is possible without contact restrictions for patients who received-up to 7 GBq. Conclusions : The TEDE: to a contact of patients treated with Ho-166. RE would not exceed the NRC limit of 5 mSv. Contact restrictions 6 hours after treatment are Unnecessary for infused activities < 7 GBq.