Radiation Dose and Hazard Assessment of Potential Contamination Events During Use of 223Ra Dichloride in Radionuclide Therapy.

An analysis is presented of the possible dosimetric consequences of various potential contamination events involving 223Ra dichloride (Xofigo), the FDA-approved therapeutic agent used in the treatment of bone metastases in patients with castration-resistant prostate cancer. Three exposure scenarios are considered: inhalation dose to an individual due to the hypothetical inhalation of 219Rn and its progeny assumed to be released into the air from a liquid spill on the floor, external dose from direct photon exposure of an individual assigned to clean up a spill, and skin dose to an individual should the liquid material come into contact with their skin. Doses from the first two scenarios were very small; 2.8 × 10(-3) mSv and 8.1 × 10(-4) mSv, respectively. Using extremely conservative assumptions, the skin dose was estimated to be 72 mSv; in a realistic scenario, this dose would likely be an order of magnitude or more lower. These doses are very small compared to regulatory limits, and good health physics practices likely to be employed in such incidents would lower them still further. The authors conclude that the medical use of Xofigo does not pose any significant radiation safety issue with respect to potential contamination events, even if multiple incidents might occur during the course of a year, since all worst-case potential contamination events considered in this study will not result in significant radiation exposures to workers.