Evaluation of the potential absorbed doses from patients based on whole-body 131I clearance in thyroid cancer therapy

The evaluation of the absorbed dose from radioactive patients during the treatment of thyroid disease is an important factor in establishing precautions in these procedures, and the I-131 retention/excretion by patients' bodies provides additional information to medical and radioprotection service. In 94 patients, the measurement of exposure rates was performed over 7 d following Na I-131 administration, and the rates permitted the study of the dynamics of excretion and the potential dose evaluation. The administered activities ranged from 3.7 GBq (100 mCi) to 16.65 GBq (450 mCi), and the results proved that the majority of the activity is excreted by patients in the first 3 d after Na 1311 administration. The average I-131 activity excreted at 24, 48, 72, 96, and 120 h after oral administration was (72 +/- 10), (91 +/- 6), (97 +/- 3), (98.9 +/- 1.5), and (99.6 +/- 0.7) %, respectively. According to the administered activity, the evaluation of the accumulated absorbed dose from patients ranged from 3.0 +/- 0.7 to 8.4 +/- 1.1 mSv at 1 in and 1.2 +/- 0.4 to 3.2 +/- 0.4 mSv at 2 in. The data reported here are important to radioprotection policy and to add to and improve on the guidelines reported in U.S. NRC Regulatory Guide 8.39.