Thyroid Cancer Total Body Scanning

The radioiodine scan (called I131 total body scan) is used to monitor for recurrence of thyroid cancer after a patient has had surgery to remove their thyroid. If you have undergone complete removal of the thyroid gland for thyroid cancer, then a radioiodine scan will reveal little to no activity in the throat where the thyroid used to be located. If recurrent or metastatic disease is present, however, there may be activity in the neck or elsewhere in the body. Identifying these early relapses is important because they may be treated with additional surgery or higher doses of radioiodine which can destroy these cancer cells. It is important to note that if the thyroid gland was not completely removed at the time of surgery, the remaining thyroid tissue will concentrate radioiodine much more efficiently than the metastatic disease will. Therefore, leftover normal thyroid tissue will make a radioiodine scan inaccurate unless this healthy thyroid tissue is removed by surgery or higher doses of radioactive iodine are used to destroy it.

When you receive a scan, an RAI pill is given in order to see if any thyroid tissue remains in your body. After the scan, you may receive treatment to eliminate any remaining thyroid tissue or to treat a recurrence, or metastases. In order to have the best test possible, the patient must follow specific preparation and precautionary instructions in order to maximize the uptake of the radioactive iodine by remaining normal thyroid tissue or metastatic thyroid cancer and reduce the risk to people around them. Instructions can be found in the section on RAI preparation and precautions.