Mayo Clinic defines a bone scan as a nuclear imaging test that is used to diagnose and monitor multiple types of bone disease. Doctors typically order bone scans if a patient has a bone injury or abnormality that can't be detected on a standard X-ray. The scans can also be used to determine if cancer that started in a different part of the body has spread to the bones.
According to WebMD, bone scans can detect problems days or months earlier than standard X-rays. They help determine the cause and location of unexplained bone pain, and they are also used to diagnose bone infections. Bone scanning involves injecting a radioactive substance into a vein. The substance travels to the organs and bones, and the radiation from the substance is detected by a camera that slowly scans the body. According to MedlinePlus, scanning the body takes approximately one hour, and patients may be asked to drink water in order to keep the radioactive substance from collecting in the bladder.
The scanning process itself is not painful, but patients may experience a bit of pain when the needle is inserted into the vein. Additionally, lying still for an extended period during the scan may cause some discomfort. The amount of radiation injected into the body before a bone scan is very small, and it is typically gone from the body within two or three days, notes MedlinePlus.