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NCI Drug Dictionary


cesium Cs 137 
A radioactive isotope of cesium with an atomic mass of 139 and potential application in radiotherapy. Cesium Cs 137 is prevalent due to its spontaneous production, which occurs as a result of nuclear fission of other radioactive materials, such as uranium and plutonium. This radionuclide has a relatively long half-life, 30 years, and decays by emitting beta particles. Both Cs 137 and its metastable nuclear isomer, barium-137m, emit gamma radiation of moderate energy and so are used in sterilization procedures in the food industry or in hospital environments. Check for active clinical trials or closed clinical trials using this agent. (NCI Thesaurus)