Iridium-192

Iridium-192 (symbol Ir192m) is an isotope of Iridium. The "m" denotes that it is a metastable isomer. Iridium-192 is used as an industrial radioisotope to locate areas of weakness in metal pipes and in radiation treatments. Its half-life is 73.83 days. It decays by emitting beta particles and gamma radiation.

Iridium-192 has accounted for the majority of cases tracked by the US Nuclear Regulatory Commission in which radioactive materials have gone missing in quantities large enough to make a dirty bomb.