Potential third‐party radiation exposure from outpatients treated with for hyperthyroidism: Third‐party radiation exposure for radiometabolic treatment

Thirty‐three hyperthyroid patients treated with radioiodine (mean administered activity 414 MBq, range 163–555) were studied to determine if pretreatment dosimetry could be used to give radiation protection advice that could assure compliance with the effective dose constraints suggested by the European Commission. Effective doses to travelers, co‐workers, and sleeping partners were estimated by integrating the effective dose rate‐versus‐time curve obtained by fitting the dose rates measured several times after radioiodine administration to a biexponential function. The mean estimated effective doses to travelers, co‐workers, and sleeping partners were 0.11 mSv (0.05–0.24), 0.24 mSv (0.07–0.52), and 1.8 mSv (0.6–4.1), respectively. The best correlation was found between effective dose in mSv and maximum activity in MBq taken up in the thyroid: ; ; . Private/public transports are always allowed. For the co‐workers the effective dose constraint of 0.3 mSv is met without restrictions and with 3 days off work if is lower or higher than 185 MBq, respectively. For the sleeping partners the effective dose constraint of 3 mSv is met without restriction and with 4 nights separate sleeping arrangements if is lower or higher than 185 MBq, respectively. The potential for contamination by the patients was determined from perspiration samples taken from the patient's hands, forehead, and neck and in saliva at 4, 24, and 48 h after radioiodine treatment. The mean highest activity levels for hands, forehead, neck, and saliva were , and , respectively. The results indicate that there is minimal risk of contamination from these patients.