Preparation and quality control of high purity 123I for clinical use

A method of producing high purity 123I for clinical use from the reaction 127I(p, 5n)123Xe and using a 123Xe → 123I generator is described. During the transport from irradiation centre to user, 123Xe decays to carrier-free 123I which is easily extracted on arrival. Results of γ spectroscopy and half-life measurements which have been carried out on the mixture of xenon and iodine isotopes received by the user and also on the 123I preparation after xenon removal, are reported. Only traces of 121Te (121Te-123I ratio at 12 h after irradiation about 0.5 106) were detected. The only long-lived radionuclide present in significant amount was 125I. The average activity ratio of 125I-123I at the adopted irradiation conditions was about 0.004 at 12 h after irradiation. (U.K.)