Monitoring of 131I in exhalation of patients administered 131I for therapy

The radioiodine concentration in exhalation of patients administered orally 131I 2-4 mCi for hyperthyroidism and 30-50 mCi for carcinoma was monitored. Patients were weared a mask with charcoal activated filter paper and 131I in exhalation was trapped with the mask during one hour using a vacuum pump of air flow 25-1 per minute. The activity of the filter paper was measured by a NaI (Tl)-scintilation detector and a 400-channel pulse height analyzer. The range of discharge rate per one hour was about 10-5 to 10-7 of the administered activity and the average rate was 3.2 x 10-6. (auth.)