ESTIMATING RADIATION ABSORBED DOSE OF INDIVIDUALS NEARBY 131I-TREATED HYPERTHYROID PATIENTS

The purpose of this study was to systematically provide a database for estimating radiation dose of individuals nearby I-131-treated hyperthyroid patients. External dose rates were measured on 48 hyperthyroid patients using a survey meter in front of patients' thyroid glands. The initial measurement was recorded within 30 min post radioiodine administration at 0.3 m, 0.6 m, 1 m, and 2 m. Follow-up measurements were carried out up to 12 d post radioiodine administration. In addition, ambient dose rates of different locations such as wards, patients' washrooms, medical staffs' workplaces, and corridors were also measured. TheNa(131)I treatment dose administered in this study ranged from 74-555 MBq. Significant positive correlation between dose rate at 1 m and the administered dose was found in this study. The normalized external dose rates at 0.3 m were 0.234 mu Sv h(-1) MBq(-1) at 0.5 h, 0.325 mu Sv h(-1) MBq(-1) at 4 h, 0.308 mu Sv h(-1) MBq(-1) at 6 h, 0.301 mu Sv h(-1) MBq(-1) at 24 h, 0.259 mu Sv h(-1) MBq(-1) at 48 h, 0.234 mu Sv h(-1) MBq(-1) at 72 h, 0.224 mu Sv h(-1) MBq(-1) at 96 h, 0.186 mu Sv h(-1) MBq(-1) at 120 h, and 0.158 mu Sv h(-1) MBq(-1) at 144 h, respectively. With these results, the authors estimated radioactive radiation dose for the public and medical staffs near I-131-treated hyperthyroid patients. This study is beneficial for radiation safety decision-making.