iodine-131

Iodine-131 is a radioactive form of iodine used mainly in medicine to treat thyroid conditions. The thyroid gland, located in the neck, naturally absorbs iodine to produce hormones. When someone has an overactive thyroid or thyroid cancer, iodine-131 can selectively target and destroy abnormal thyroid tissue with radiation. It emits radiation that damages the cells but is mostly confined to the thyroid area, sparing other parts of the body. Because it decays quickly, iodine-131 has a relatively short half-life, making it effective for treatment while minimizing long-term radiation exposure.