[Radiation risk during radionuclide diagnosis of thyroid diseases]

A cytogenetic study was performed in 2 groups of patients with nodular euthyroid goiter (aged 40 to 50) who underwent radiodiagnostic examination under out-patient conditions. The patients of the 1st group received 0.18 MBq of 131I and then during scanning 1.7-4.0 mBq of 131I. An absorbed dose in the thyroid grew from 8 mSv on the 1st day to 1700 mSv by the 90th day. In the patients of the 2nd group dose exposure was decreased by 1.5-fold. A high cytogenetic toxicity of 131I was revealed: the total number of chromosome aberrations (NCA) increased in parallel with changes in their structure. NCA restoration up to the spontaneous level was undetectable even in 90 days. A decrease in dose exposures did not result in a proportional decrease in a cytogenetic effect of 131I irradiation.