Protection problems in radionuclide therapy: the patient as a gamma-radiation source

Estimates have been made of the rate of uptake, metabolism and excretion of radioiodine given in treatments of patients with hyperthyroidism or thyroid carcinoma. Average values for the exposures to be expected at a given distance from such patients, and the variability of such exposures, are derived from these data. The mean exposure of a patient in an adjacent bed, at 2.5 m bed spacing, following typical therapeutic doses of 131-I in the treatment of hyperthyroidism or thyroid carcinoma, is estimated to be about 0.02 or 0.08 R respectively. Variations in the metabolic parameters would increase these exposures to about 0.03 and 0.14 R, at the 90 percentile values. Exposures following treatments with 100 mCi of 198-Au, or of 300 mg days of -226Ra would be about 0.2 and 0.6 R.