If you have been diagnosed with prostate cancer, your doctor may ask you to undergo some tests to determine whether the cancer has spread beyond the prostate. A bone scan is one of these tests. Usually, doctors recommend bone scans only to those men who are at a high risk for metastases (e.g., Gleason Score 8-10, PSA over 20, or clinical stage T3 or greater). Why? Metastases do not usually register on bone scans unless the cancer is aggressive, the PSA number is high, or the stage is at least T3-but many other abnormalities, such as old injuries, do.

A bone scan uses small amounts of radioactive material and a specialized camera to create pictures of the skeleton. Specifically, a gamma camera shows how your bones absorb nutrients and takes pictures of bone metabolism.

The radioactive material is injected into a vein in your arm. Because this material takes some time (about two to four hours) to circulate and become absorbed by the bones, you must wait to be photographed (scanned). Sometimes, you are able to leave the hospital or medical centre for this period.

During the scan, you usually lie still on a table or flat surface while the machine holding the gamma camera passes closely over your body and records the pattern of radiation waves that your body emits. If prostate cancer has spread to the bones, it often show up as a series of darker areas (called "hot spots") along the spine or the ribs.

Remember, however, that various abnormalities in bone metabolism show up on a bone scane, e.g., stress fractures, arthritis, or bone infections. The bone scan shows whether there is an abnormality, but it is less helpful in showing the cause of an abnormality.