How It Is Done continued...
For this test, you will lie on your back with your head tipped backward and your neck extended. It is important to lie still during this test. A special camera (called a gamma scintillation camera) takes pictures of your thyroid gland from three different angles. The test takes about 30 minutes.
For a whole-body thyroid cancer scan, the camera will scan your body from head to toes.
After a thyroid scan, you can do your regular activities. But you will be asked to take special precautions when you urinate. This is because your body gets rid of the radioactive tracer through your urine. This takes about 24 hours. During this time, it is important to flush the toilet twice each time you use it and wash your hands thoroughly after each time you urinate.
How It Feels
You may find it uncomfortable to lie still with your head tipped backward.
There is always a slight chance of damage to cells or tissue from radiation, including the low levels of radiation used for this test. But the chance of damage from the radiation is usually very low compared with the benefits of the test.
This test is not done for pregnant women because of the chance of exposing the baby (fetus) to radiation. This test is also not recommended for breast-feeding women or young children.
A thyroid scan uses a radioactive tracer and a special camera to make a picture of the thyroid gland. The radioactive tracer used in this test is usually iodine or technetium. A thyroid scan is done to help find problems with the thyroid gland.
A normal thyroid scan shows a small butterfly-shaped thyroid gland about 2 in. (5 cm) long and 2 in. (5 cm) wide with an even spread of radioactive tracer in the gland.
An abnormal thyroid scan shows a thyroid gland that is smaller or larger than normal. It can also show areas in the thyroid gland where the activity is less than normal (cold nodules) or more than normal (hot nodules). Cold nodules may be related to thyroid cancer.
A whole-body scan will show whether iodine is in bone or other tissue (iodine uptake) after the thyroid gland has been removed for cancer. The whole-body scan can check to see if cancer has spread to other areas of the body.