A bone scan is an imaging test used to help diagnose problems with your bones. It safely uses a very small amount of a radioactive drug called a radiopharmaceutical. It has also been referred to as a “dye,” but it doesn’t stain the tissue. Specifically, a bone scan is done to reveal problems with bone metabolism. Bone metabolism refers to the process in which bones break down and rebuild themselves. New bone formation is part of the healing process when bones are injured or broken. A bone scan is a good way to view and document abnormal metabolic activity in the bones. A bone scan can also be used to determine whether cancer has spread to the bones from another area of the body, such as the prostate or breast. During a bone scan, a radioactive substance is injected into a vein that is taken up by your bones. You’ll then be monitored for several hours. A very small amount of radiation is used in the substance, and nearly all of it is released from your body within two or three days.