[Radiation exposure around patients after administration of 123-MIBG].

Aim: Estimation of the radiation exposure to neighbouring patients, personnel and relatives deriving from patients undergoing 123I-MIBG scintigraphy.
Methods: For scintigraphic studies, 16 patients with suspected pheocromocytoma were injected with 340 +/- 30 MBq 123I-MIBG. Dose rates were measured at a distance of 0.5 m, 1 m, and 2 m after 10 min, 3 h, 21 h, 45 h, and 68 h using three calibrated portable radiation detectors. The emasured values were background corrected.
Results: Ten minutes after injection the dose rate was 10.5 microS/h at a distance of 0.5 m, 3.78 microS/h at 1 m, and 0.95 microS/h at 2 m. The effective half-life was estimated to 8.68 +/- 0.15 h. The maximum dose in a distance of 1 m for neighbouring patients was 46 microS/h, for personnel in a ward 27 microS/h, and to relatives in a distance of 2 m 12 microS/h.
Conclusion: This study demonstrates that the calculated exposure to people around patients after 123I-MIBG injection is well below the maximum permissible annual dose limit of 1 mSv for not professionally exposed persons.