A bone scan identifies changes in how bone is growing or breaking down. In a three-phase bone scan, bones are scanned three times, several hours apart.
How a Scan is Done
For a bone scan, a radioactive material is injected into a vein. A camera slowly scans your body, taking pictures of how much radioactive material collects in your bones.
Why a Bone Scan?
A bone scan is done to identify anomalous happenings in bone, such as tumor, infection or fracture.
Three Phase Bone Scan
In a three-phase bone scan images are taken immediately after the injection, four hours after the injection, and 24 hours after the injection, according to the University of Tennessee Medical Center.
Why a Three Phase Bone Scan?
A three-phase bone scan is done if your doctor suspects you have osteomyelitis, a bone inflammation caused by bacteria or virus.
For each scan, you must lie motionless for about 20 minutes.