A bone scan is an imaging test used to look at the skeleton. It's done to find areas of physical and chemical changes in bone. A bone scan may also be used to see if treatment of certain conditions is working.

A bone scan is a type of nuclear radiology procedure. This means that a tiny amount of a radioactive substance is used during the scan to help in examining the bones. The radioactive substance is called a radionuclide or radioactive tracer. It may either be increased or decreased in abnormal areas of bone.

The radionuclide gives off a type of radiation, called gamma radiation. The gamma radiation is detected by a scanner. The scanner uses the information to make a picture of the bones.

The areas where the radionuclide collects are called "hot spots." They may be a sign of conditions, such as cancerous bone tumors and metastatic bone cancer. This is cancer that has spread from another site, such as the lungs, to the bones. Other conditions include those related to the bone. These include bone infection and bone injury not seen on regular X-rays.

Bone scans are most commonly used to look for the spread of cancer. The bone surrounding the cancer will appear as a hot spot on a bone scan. This is due to increased bone activity in the area of the cancer cells. Bone scans may also be used to see how much cancer there is before and after treatment to see if the treatment is working.

Other reasons for doing a bone scan may include:

• To assess for bone injury or damage when regular X-rays don't show the problem
• To find fractures that are hard to locate
• To determine the age of fractures
• To detect or assess bone infection (osteomyelitis)
• To look for the cause of unexplained bone pain
• To detect and assess conditions, such as arthritis and bone tumors

There may be other reasons for your doctor to recommend a bone scan.

The amount of the radionuclide injected into your vein for the procedure is small enough that there is no need for precautions against radioactive exposure. The injection of the tracer may cause some slight discomfort. Allergic reactions to the tracer are rare but may happen.

There may be other risks depending on your specific health condition. Be certain your doctor knows about all your health conditions before the procedure.

• Your doctor will explain the procedure to you, and you can ask questions. Make a list of questions and any concerns to discuss with your doctor before the procedure. Consider bringing a family member or trusted friend to the medical appointment to help you remember your questions and concerns and to take notes.
• You will be asked to sign a consent form that gives your permission to do the test. Read the form carefully and ask questions if anything is not clear.
• Generally, no preparation is needed, such as not eating or not taking medicine, before a bone scan.
• Tell your doctor, the radiologist, or the technologist if you are allergic to or sensitive to medicines, contrast dyes, or iodine.
• Tell your doctor if you are pregnant or think you may be.
• Tell your doctor if you are breastfeeding.
• Make sure your doctor has a list of all prescribed and over-the-counter medicines, and all herbs, vitamins, and supplements that you are taking.
• Based on your health condition, your doctor may give you other instructions on what to do before the bone scan.

A bone scan may be done on an outpatient basis or as part of your stay in a hospital. Procedures may vary depending on your condition and your doctor's practices.

Generally, a bone scan follows this process:

1. You will be asked to remove any clothing, jewelry, or other objects that may get in the way of the scan. A bracelet with your name and an identification number may be put on your wrist. You may get a second bracelet if you have allergies.
2. If you are asked to remove your clothing, you will be given a gown to wear.
3. An I.V. (intravenous) line will be started in your hand or arm for injection of the radioactive tracer.
4. The tracer will be injected into your vein. The tracer will be allowed to collect in the bone tissue for a period of 1 to 3 hours. You may be allowed to walk around or even leave the facility during this time. You will not be hazardous to other people, as the tracer gives off less radiation than a standard X-ray.
5. During the waiting period, you will need to drink 4 to 6 glasses of water to help flush out any tracer that does not collect in the bone tissue.
6. If your bone scan is being done to look for bone infection, a set of scans may be done right after the injection of the tracer. Another set of scans will be done after the tracer has been allowed to collect in the bone tissue.
7. When the tracer has been allowed to collect in the bone tissue for the right amount of time, you will be asked to empty your bladder. This is because a full bladder can distort the bones of the pelvis and may become uncomfortable during the scan.
8. You will be asked to lie still on a padded scanning table. Any movement may affect the quality of the scan.
9. The scanner will move slowly over and around you several times as it detects the gamma rays given off by the tracer in the bone tissue.
10. You may be repositioned during the scan to get certain views of the bones.
11. When the scan has been completed, the I.V. line will be removed. It takes about 1 hour to do a full body scan.

While the bone scan itself causes no pain, having to lie still for the length of the procedure might be uncomfortable, particularly if you have recently had surgery or an injury. The technologist will use all possible comfort measures and complete the procedure as quickly as possible to reduce any discomfort or pain.

Move slowly when getting up from the scanner table to prevent any dizziness or lightheadedness.

You will be instructed to drink plenty of fluids and empty your bladder often for 24 to 48 hours after the scan. This will help flush the remaining tracer from your body.

The I.V. site will be checked for any signs of redness or swelling. If you notice any pain, redness, or swelling at the I.V. site after you go home, you should tell your doctor. It may be a sign of infection or other type of reaction.

You should not have any other radionuclide procedures for the next 24 to 48 hours after your bone scan.

You may go back to your usual diet and activities, unless your doctor tells you differently.

Your doctor may give you other instructions after the procedure, depending on your particular situation.

Before you agree to the test or procedure, make sure you know:

• The name of the test or procedure
• The reason you are having the test or procedure
• What results to expect and what they mean
• The risks and benefits of the test or procedure
• What the possible side effects or complications are
• When and where you are to have the test or procedure
• Who will do the test or procedure and what that person's qualifications are
• What would happen if you did not have the test or procedure
• Any alternative tests or procedures to think about
• When and how you will get the results
• Who to call after the test or procedure if you have questions or problems
• How much you will have to pay for the test or procedure