Radiochemical Purity of ¹²³I for Medical Use

Abstract

¹²³I for use in clinical diagnostic procedures has been produced by bombarding antimony with 40 MeV ³He particles. The purity of ¹²³I was measured with a Ge (Li) spectrometer and a low energy Ge (Li) detector. The ¹²³I-product was followed for 1.5 months with a well-type NaI scintillation counter to establish the half-life and confirm the identity of the nuclides. In order to minimize the yield of ¹²¹I the optimum cooling time and chemical procedures are presented. After 20h cooling, the ¹²¹I, ¹²⁴I and ¹²⁵I contaminants were about 1.8, 4.3 and 0.04% respectively. These values were in agreement with those calculated from the thick-target yield curves.
The calculated absorbed dose to the thyroid by the ¹²³I and by-product nuclides were only 4.3 and 7.3% of ¹³¹I. ¹²³I could be measured at the window of ^99mTc of a NaI scintillation camera and a curie-meter with an error of 10%.