Bone scans are important in cancer and particularly prostate cancer for two reasons. Firstly prostate cancer typically metasizes to the bone when it starts to spread and secondly hormone therapy has the side effect of bone thinning and initiating the early onset of osteoporosis.
There are two types of bone scans which relate directly to these two aspects of prostate cancer and changes in the bone.
A radionuclide scan (also known as a scintigram) involves injecting a small amount of radioactive dye. A gamma camera then is able to scan the body and produce what looks exactly like an X-ray which shows up ‘hot spots’ where there is particular activity in the bone. Activity here means that the bone is breaking down and/or trying to repair itself and although this is not proof of cancer, that is the most likely explanation for such a reading.
The second type of scan is a Bone Density Scan known as a DXA scan This scan involves being scanned by a special X-ray machine. Basically you just lie down on a table and this machine scans your body, normally just the pelvic area. It doesn’t involve any injections and is painless. This type of scan measures bone density and provides a measure of bone density normally presented as a T score.
A score above -1 is considered normal. Between -1 and -2.5 indicates a lowering of bone mass and is referred to as osteopenia. If the score falls below -2.5 it signals the presence of osteoporosis – a significant thinning of the bone.
