radioactive iodine
definition of radioactive iodine
1. a type of iodine that is created by nuclear power plants and nuclear bombs. It can enter your body if you are exposed to contaminated air, food, or water. In the body, radioactive iodine collects in your thyroid and can damage the gland. At careful doses, radioactive iodine is also used in nuclear medicine. It is used in imaging tests to diagnose thyroid problems, and in cancer treatment to kill thyroid tumor cells.1