Carrier-free 194Ir from an 194Os/194Ir generator—a new candidate for radioimmunotherapy

Abstract Iridium-194 ( t 1 2 = 19.15 h ) decays by beta-particle emission ( E max = 2.236 MeV) and is a potential candidate for radioimmunotherapy. An important characteristic is availability of 194 Ir from decay of reactor-produced 194 Os ( t 1 2 = 6 y ). We report the fabrication of the first 194 Os/ 194 Ir generator system using activated carbon. In addition, a novel gas thermochromatographic method was developed for the one step conversion of metallic Os to OsO 4 and subsequent separation and purification of OsO 4 . In this manner, the reactor irradiated enriched 192 Os target was converted to 194 OsO 4 , which was then converted to the K 2 OsCl 6 for generator loading. The yield and the elution profile of carrier-free 194 Ir, and 194 Os breakthrough were determined for a prototype generator which was evaluated over a 10-month period.