with an emission probability of 3 3 and with energy of 324 kev with an emission probability of 2 8 respectively u 230 can either be used directly for medical purposes or can be utilised as a parent nuclide for the production of th 226 to this end u 230 can be fixed on a radionuclide generator extraction chromatographic material or ion exchanger that allows the selective elution of th 226 at regular or determined time intervals ac 226 has a half life of 29 h and decays through u03b2 u2212 emission with a branching ratio of 83 to th 226 it also decays through positron emission 0 64 mev with a branching ratio of 17 to ra 226 as well as through alpha decay to fr 222 with a low branching ratio of 6 u00b7 10 u2212 3 the decay chain of ac 226 is shown in fig2 due to the longer half life of ac 226 t 1 2 29 4 hours compared to th 226 t 1 2 31 min a radiopharmaceutical containing ac 226 can be used to target cells that are less readily accessible than in the case of using th 226 the decay of ac 226 will produce in situ short lived th 226 with its favourable decay characteristics and the emission of multiple alpha particles resulting in the.