Iodine-131 bioaccumulation in regions where radioiodine has sufficiently contaminatated the environment. Iodine-131 is used for unsealed source radiotherapy in nuclear medicine to treat several conditions. It can also be detected by gamma cameras for diagnostic imaging, however it is rarely administered for diagnostic purposes only, imaging will normally be done following a therapeutic dose. Use of the I as iodide salt exploits the mechanism of absorption of iodine by the normal cells of the thyroid gland. Major uses of I include the treatment of thyrotoxicosis (hyperthyroidism) due to Graves' disease, and sometimes hyperactive thyroid nodules (abnormally active thyroid tissue that is
Isotopes of iodine iodine-135 can temporarily preclude a shut-down reactor from restarting. This is known as xenon-poisoning or "falling into an iodine pit". Iodine fission-produced isotopes not discussed above (iodine-128, iodine-130, iodine-132, and iodine-133) have a half lives of a couple of hours or minutes, rendering them almost useless in other applicable areas. Those mentioned are neutron-rich and so go through beta decay to their xenon counterparts. Iodine-128 (25 min half-life) can decay to either tellurium-128 by electron capture, or to xenon-128 by beta decay. It has a specific radioactivity of 2.177 x 10 TBq/g. Colloquially, radioactive materials can be described as "hot,"