A bone scan is essentially used to diagnose the spread of cancer to the bones and it is an imaging tests. It is medically known as scintigraphy. This test may be done in the early days to assess that the bones are functionally fine and healthy and the cancer has not still invaded the bone tissue. The bone scan may also be undertaken in between the treatment course or after the therapy. This is usually done when the patient complains of joint pain, persistent pain in the bones or any other indication suggesting that the bone may be infected. The early scans are useful in tracking in changes in future bone scans due to the cancer.
In these scans a radioactive material is injected in the arm. It is absorbed in about 2 – 4 hours and absorbed by the bone making cells. The concept is that these bone making cells are usually at the cancer site where the cancer cells have destroyed healthy cells. To make up for the destroyed cells bone making cells become effective to generate new cells. Thus with the help of a special camera the doctor is able to track these bone making cells. Thus the radioactive material binds with the cells and shows in scan at the new bone making areas and the cancer location in the bone structure. These areas look like dark patches in the image /film and the patient needs to lie down for the complete scan. It is generally a pain less procedure and similar to a normal x-ray as regards radiation exposure. This bone scan along with cancer site can also highlight other similar changes though not due to cancer. Like arthritis and in spine where the bone structure is quite complex, one may need to do additional tests for cancer evaluation in the joints.
This scan is predominantly advised or performed on patients with invasive cancer which spreads to other parts of the body. Cancers like DCIS do not warrant this test. If a patient complains of persistent pain in the back bone and joints bone scan should be undertaken for the clearance of cancer detection. Also this bone scan is different from a bone density test called DEXA to assess bone thickness, the two should not be confused with each other.