A bone scan is a test used to show trouble spots on the spine. A radioactive chemical, sometimes called a "tracer", is injected into the bloodstream. The chemical quickly attaches itself to areas of the skeleton that are busy making new bone. Several hours after the injection, pictures are taken of the skeleton.
A bone scan is very useful when it is unclear exactly where the problem is in the skeleton. It offers the ability to take a picture of the entire skeleton and pinpoint any problem areas. Concentrations of the chemical "tracer" appear as dark spots on the film.
In an adult, dark spots usually indicate that there is a problem with the skeleton. The increased bone-making activity that the dark spots represent is the skeleton's response to the problem. For example, if there is a bone fracture, bone cells will very quickly begin to make new bone to try to repair it. That activity will appear as a dark spot on a bone scan. If a dark spot is located on the bone scan, the doctor may order additional tests to get more specific information about your condition.
An intravenous (IV) line is started in your hand or arm. The chemical tracer is then injected into your bloodstream through the IV. There is a waiting period of two to three hours, while the chemical attaches itself to any areas of bone that are undergoing rapid changes. You may be free to leave during this waiting period and come back when it is time to perform the bone scan.
When it is time to perform the bone scan, you will then be asked to lie or sit underneath a large "camera" that takes pictures of your skeleton. Since the chemical tracer is radioactive, it sends out radiation that this special camera is able to capture. The camera is similar to a "Geiger counter" in that it uses film to capture the radioactivity. The procedure takes 30-90 minutes.
The bone scan does not show details of the bones or soft tissue. It simply shows how much the bone around a specific area is reacting to the problem.
There is always the risk of an allergic reaction to anything injected into the bloodstream. An allergic reaction to the chemical tracer used in a bone scan is uncommon. The chemical is radioactive, but it disappears from the body very rapidly, usually within hours.