During a bone scan, a radioactive chemical is injected into the bloodstream. This chemical adheres to parts of the bone which are undergoing rapid changes. After a gamma camera scans the area, these parts show up as dark areas on the film. Once the physician has identified the affected area of the spine, other tests may be given to look at the area more closely.

The bone scan is safe since the levels of radiation in the chemical are very low—even lower than the levels one is exposed to during plain X-rays.