A bone scan is a nuclear medicine test used to diagnose many different types of bone problems and diseases. The procedure uses a small amount of a radioactive substance called a tracer, which shows possible bone damage in areas where the body has absorbed too much or too little tracer. The reason your doctor may perform a bone scan during diagnostic tests is to see if that bone damage could involve cancer.
Using a bone scan when cancer is suspected can be especially helpful because the scan can find both primary cancer — or cancer that started in the bones — and bone metastases, which is cancer that has spread to the bones from another part of the body. Some cancers that may involve bone metastases include breast cancer, lung cancer, lymphoma, and others. A bone scan can also find changes in the bones much earlier than they can be seen by a normal X-ray.
Another reason your doctor might order a bone scan is if you've already been diagnosed with bone cancer. This is because a bone scan may be used to check how well bone cancer treatment is working.
For the scan itself, you can go to the Department of Radiology or the Department of Nuclear Medicine at a hospital or outpatient imaging center. Before the bone scan, you will be given a small amount of tracer through a vein in your arm. This will take between one and four hours to absorb. You will usually have a whole-body bone scan, which takes about 1 hour.
During the bone scan, the tracer emits a type of radiation called gamma radiation, and a camera scans the body and detects this radiation. Healthy bone looks clearer on the scan. Areas where the body has absorbed too much or too little tracer are highlighted in the picture and are called "foci." These foci indicate bone damage, which could indicate bone cancer or bone metastases. If your bone scan shows bone damage, your doctor may recommend more tests. Talk to your doctor before your scan about why you're having a scan, any special test preparations you may need to have, and what the results might mean for your cancer care.