How a bone scanner works:

A bone scan looks for changes or abnormalities in the bones. It is also called a radionuclide scan, a scintigram or nuclear medicine scan. 
A bone scan can look at a particular joint or bone. In cancer diagnosis, it is more usual to scan the whole body. The scan involves one injection but apart from that, it is painless.
The scan uses a large camera called a gamma camera. Gamma cameras pick up radioactivity. To have the scan, you first have a radioactive substance called a radionuclide injected into your bloodstream. You only need a very small amount of this radioactive substance – not enough to do you any harm. The radionuclide travels through the blood and collects in your bones. It tends to collect more in areas where there is a lot of activity in the bone. Activity means the bone is breaking down, or repairing itself. These areas of activity are picked out by the camera. Doctors call them hot spots. They show up as dark areas on the scan. Below is an example of a bone scan.

Hot spots can be due to cancer in the bones, but they can also be caused by other medical conditions. Bone can break down and repair for different reasons. For example, if you have arthritis or an old fracture this may also show up on the scan.
You have the scan in either the medical physics department, nuclear medicine department or X-ray department at the hospital. You will have to arrive up to 4 hours before your scan to allow for the radionuclide to travel throughout your body and collect in the bones. The staff at the hospital or clinic will tell you beforehand exactly when you need to arrive.
When you arrive, you have the injection of radionuclide into a vein. Before you have this, the radiographer will ask you about allergies or asthma as some people can be allergic to it. The injection may make you feel hot and flushed for a minute or two. Immediately after the injection you may have a quick scan. Then you will be free to leave the department for a couple of hours. The radiographer will tell you exactly when you have to be back.
The radiographer will ask you to drink plenty while you are away. It doesn't really matter what you drink – you just need to flush the injection through your body. The radiographer will ask you to pass urine just before you return (or when you return) to get rid of any radionuclide in your bladder. Otherwise this could interfere with the scan.
When you go back to the department, you usually go straight into the scanning room. You may have to undress and put on a hospital gown first, but this isn't always necessary.
When you are ready for the scan, you will lie down on an X-ray couch and will need to keep still. The gamma camera then takes pictures of the whole of your skeleton. Your body goes through the scanner. This makes some people feel claustrophobic, so let your radiographer know if you feel nervous as they can help to reassure you. The scan can take up to an hour.
After the scan, you will usually be free to go home. It can take up to 24 hours for the radionuclide to get out of your system. It will help if you drink plenty during this time.


Preparation for the scan:

There are no special preparations for a bone scan. You don't have to restrict what you eat or drink.


 Possible risks from a bone scan:

A radioactive injection does sound dangerous, but you will only have a small amount of radiation given to you. Doctors make sure the benefit of having the test outweighs the low risk linked to radiation. The body gets rid of the radionuclide in the urine. This takes up to 24 hours. 
Although the level of radiation is small, your doctor will recommend that you do not have long periods of close contact with pregnant women, babies and young children until the day after your scan. If you are pregnant or breast feeding, you must phone the department where you are due to have the scan for advice. They will let you know if you need to stop breast feeding for a length of time after having the radionuclide injection. You may need to store enough expressed milk for at least one feed. If there is a possibility you might be pregnant, you may not be able to have a bone scan. This is because the radionuclide could cross the placenta and affect the baby.
If you are travelling abroad within a few days of your bone scan, it may be a good idea to take your appointment letter with you to show that you have had a scan. Most airports have sensitive radiation monitors which may pick up the trace of radiation following your test.

The results:

It can take time for test results to come through. How long will depend on why you are having the scan but it may be up to a couple of weeks. Usually, a specialist in radiology or nuclear medicine examines the scan and a report is typed up. The report is then sent to your specialist, who gives the results to you. If your GP has sent you for the test, the results will be sent directly to the surgery.
Understandably, waiting for results can make you anxious. If your doctor needs the results urgently, they will make a note of this on the scan request form. Try to remember to ask your doctor how long you should expect to wait for the results when they refer you for the test. If it is not an emergency, and you have not heard a couple of weeks after your test, ring your doctor's secretary or specialist nurse to check if they are back.