<prompt> Half life of cobalt-60 is -74.5 years5.2 years30 years2.6 years  <response>: Impoant Radioisotopes Half Life RADIOISOTOPE HALF LIFE IODINE 131 8 DAYS IODINE 125 60 DAYS IODINE 124 4 DAYS IODINE 123 13 HOURS PHOSPHORUS -32 14 DAYS RADIUM RA-226 1622 years Cobalt -60 5.2 years Cesium - 137 30 years TC- 99m 6 hours Iridium Ir-192 74.5 Days 18F 18FDG 110 min Strontium 89 50.5 days 