A bone scan is a nuclear medicine procedure that generates an image of the bones' metabolism. Tracers, which are minuscule quantities of radioactive material, are used in nuclear medicine (radionuclides). These tracers accumulate in some organs and tissues, including bones. The imaging process uses a gamma camera to record the location and amount of radioactivity within the body. The bone scan shows areas of high activity (hot spots) as well as low activity (cold spots). These areas represent sites where tissue is undergoing active growth or repair. The presence of hot spots indicates that something other than just bone loss is causing your blood levels to rise. For example, if you had cancer or another disease that caused your blood cells to break down faster than normal, there would be more hot spots on the bone scan. Organs such as the stomach, intestines, bladder, and reproductive organs contain DNA that is similar to DNA found in bone marrow cells. Thus, these organs can be visualized on a bone scan. The presence of cold spots may indicate that cancer has spread from its original site to other parts of the body. For example, if multiple cold spots appear on the bone scan, this may indicate that cancer has metastasized (spread) to the bones. Another use for the bone scan is to look for lesions (growths) on bones that cannot be seen on X-rays.