Radiotherapy for thyroid cancer

Radiotherapy means the use of radiation, to treat cancer cells. For thyroid cancer you might have radiotherapy from:

• inside the body (internal radiotherapy) - this is radioactive iodine (iodine 131)
• outside the body (external radiotherapy)

Radioactive iodine uses a radioactive form of iodine called iodine 131 (I-131).  Thyroid cells absorb iodine 131 and the radiation in the iodine kills the cancer cells.  External radiotherapy uses high energy waves similar to x-rays to destroy cancer cells. A radiotherapy machine aims radiation beams at a cancer.