Radiation Exposure to the Nuclear Medicine Personnel During Preparation and Handling of ²¹³Bi-Radiopharmaceuticals

Abstract

Because of the excellent ability of α-particles to transfer a high amount of energy over a short tissue range, targeted α-therapy has been attracting rising numbers of nuclear medicine centers. In this study, we estimated the radiation exposure to the occupational workers with pocket dosimeters during handling of the α-emitter ²¹³Bi, used for targeted α-therapy of neuroendocrine tumor and castration-resistant prostate cancer patients. The dose rates from patients at different distances and time points after injection of the therapy were also evaluated. Methods: This prospective study was done in the Department of Nuclear Medicine at Fortis Memorial Research Institute, Gurgaon, India. Twelve patients with neuroendocrine tumors or castration-resistant prostate cancer were enrolled to receive ²¹³Bi-DOTATOC or ²¹³Bi-prostate-specific membrane antigen therapy, respectively. Each patient received 2–3 intravenous injections of ²¹³Bi-peptide, 266–362 MBq (7.2–9.8 mCi) in a single cycle over 2–3 d. The radiation exposure to nuclear medicine personnel at the chest and extremity levels was assessed for tasks such as elution, dispensing, injecting, and collecting blood samples. Radiation levels were measured at distances of 1 cm and 1 m from patients immediately after, and at 1, 2, and 4 h after, the administration of ²¹³Bi-peptide. Results: The external dose incurred at the chest level by radiopharmacists during synthesis, by physicians during injection, by technologists during imaging, and by nurses during sample collection was 2–7 μSv/procedure. The extremity dose was 1–14 μSv/procedure. The dose rate at 1 m from patients immediately after ²¹³Bi-radiopharmaceutical injection was 0.02–0.03 μSv/MBq⋅h. Conclusion: The external radiation doses received by occupational workers involved in various procedures were far below the limit prescribed by the regulatory authority (20 mSv/y).