A bone scan is a nuclear test in which a tracer (radionuclide) is injected into the body to obtain a little more detailed look at the bones and joints than a traditional x-ray. In about 3 to 4 hours after the injection, tracers accumulate in certain organs and tissues, such as bones. Once introduced into the body, they emit waves of radiation that are detected by a special gamma camera. This camera produces images that are interpreted by radiologists or nuclear medicine specialists. The images will show how the dye is absorbed by the bones; normal areas will be gray while darker areas indicate a problem.