Iodine-131

I-131 major uses include the treatment of thyrotoxicosis (hyperthyroidism) and some types of thyroid cancer that absorb Iodine. I-131 is thus used as direct radioisotope therapy to treat hyperthyroidism caused by Graves’ disease, as well as in hyperactive thyroid nodules. It is also employed as a radioactive label for certain therapeutic radiopharmaceuticals, such as I-131-metaiodobenzylguanidine (I-131-MIBG), used for imaging and treatment of pheochromocytoma and neuroblastoma. In these therapeutic applications, I-131 destroys tissues by emitting short-range beta radiation. Beta radiation is responsible for about 90% of the tissue damage; the isotope’s gamma radiation responds for the remaining destruction. In therapeutic applications, I-131 can also be visualized in diagnostic scans, due to detection of its emitted gamma radiation.