The person who does the scan is called a radiographer. They inject a small amount of a radioactive substance through a cannula into a vein in your hand or arm. This is called a tracer. The amount of radiation used is small. It does not cause you any harm.
You need to wait for 2 to 3 hours between having the injection and having the scan. You may want to take something to help pass the time.
Areas of abnormal bone absorb more radiation than normal bone. This means the abnormal bone shows up more clearly on the scanner. The abnormal areas are sometimes called hot spots.
It is not always clear whether hot spots are caused by cancer or by other conditions, such as arthritis. Sometimes doctors also use a CT or MRI scan to help them decide. Some hospitals do an MRI scan of the whole skeleton instead of a bone scan. This is to check for signs of cancer in any other bones in the body.