A bone scan is a test that detects areas of increased or decreased bone metabolism (turnover). The test is performed to identify abnormal processes involving the bone such as tumor, infection, or fracture. A radiotracer (bone-seeking radionuclide) is injected into the bloodstream through a vein. As it decays, the radiotracer emits gamma radiation, which is detected by a camera that slowly scans your body. The camera captures images of how much radiotracer collects in the bones. The scanning part of the test will last about an hour and may require moving to various positions.