Indium-111 is an isotope of indium with a radioactive half-life of 2.80 days, making it useful as a radioactive tracer. It is made for this use by the Nordion(Canada) Inc. unit of Nordion, Inc. as indium-111 chloride solution, and shipped to several firms which sterilize the pure solution, combine it with carrier compounds if needed, and repackage it for medical and industrial uses.
Among the medical applications of indium-111 are specialized diagnostic uses:
Indium-111 decays by electron capture to cadmium-111, emitting a 0.1713 and 0.2454 MeV gamma rays with a 2.8047 day radioactive half-life. The parent isotope of indium-111 is tin-111, with a decay mode of electron capture. Indium-111 also undergoes isomeric transition, emitting a 0.537 MeV gamma ray with a 7.7 minute half-life.