Airborne radioiodine contamination caused by 131I treatment.

Estimation of exposure from 131I inhaled from unsealed sources during laboratory procedures and from that exhaled by patients treated with 131I has revealed that the permissible levels have been exceeded by a factor of 2-5, although the absorbed activity was found to be between 1 and 10% of the maximum permissible absorption of 131I inhaled through the lungs. The fall in 131I concentration in the air exhaled by 19 hyperthyroid patients, to whom 131I was administered in a dose of several hundred MBq, could be expressed by a two-component equation, which reflects the changes in 131I concentration in the blood.

Adrenal scintigraphy with 131-I-adosterol.

A new adrenal scanning agent, Adosterol (131I-6beta-iodomethyl-19-norcholest-5(10)-en-3beta-ol) has been evaluated in three female patients with hypercorticism. In one case, characterised by recurrent adrenocortical hyperactivity after bilateral adrenalectomy, a remnant of adrenal tissue was detected. In two other cases, the presence of an adrenal tumour could be excluded.

Some comparative studies using 99mTc and 131I in thyroid scanning.

By comparing thyroid scans made with 99mTc and 131I in 40 euthyroid goiter patients large discrepancies were found in 20% of all cases. For example, "warm" nodules on 99mTc scans were found to be "cold" on 131I scans, or a "cold" nodule on a 99mTc scan was observed as a "warm" one on a 131I scan. The above discrepancies seem to result from the differences in the metabolism of the two radioisotopes in the thyroid and those in the time which elapsed between the administration of the radioisotope and the execution of the scan.