What is radioactive iodine (RAI) therapy for thyroid cancer?
Iodine is a mineral found in certain foods. Cells in your thyroid gland absorb iodine and use it to make thyroid hormone. The thyroid heavily relies on iodine for proper function.
Most thyroid cancer cells also absorb iodine. Penn Medicine experts use a special type of iodine called radioactive iodine (RAI) to image thyroid cancer and destroy these cancer cells.
We use different isotopes (types of radioactive iodine named for their atomic weight) to diagnose and treat thyroid cancer. These isotopes include:
We use this isotope, which emits less radiation, during radioactive iodine scans to see if thyroid cancer has spread (metastasized). You take a capsule containing a small amount of I-123 (iodine 123). Special cameras then scan for cancer cells, which take up I-123 and become visible.
Experts use this isotope to deliver radiation directly to tissues during radioactive iodine therapy. We use I-131 (Iodine 131) after surgery for thyroid cancer to eliminate any remaining thyroid tissue and destroy remaining cancer cells. I-131 can also be used for thyroid cancer that recurs after initial treatment, especially for the rare instances where it has spread to other parts of the body.