You will also have either a bone scan or positron emission tomography / computed tomography (PET/CT) during the screening period to check if the disease has spread to your bones. A bone scan is a picture that is taken, after a radioactive substance is injected into your bloodstream, allowing your doctor to see any abnormal areas of the bone. A PET/CT scan is a type of x-ray scan that uses an injected chemical to help the doctor "see" the image more clearly. For up to 6 hours before the PET/CT scan, you must not eat or drink anything except water. A small tube will be placed in your arm, and you will receive an injection of a very small amount of a mildly radioactive sugar material into your bloodstream. The radioactive nature of this injected material allows the scanner to "see" it in certain places in your body. After the injection, you will need to rest quietly until it is time for the scan. The amount of rest time may vary, but be prepared to wait for between 45 and 90 minutes. During the scan, you will lie flat on your back on a table. The scan itself may last up to 1 hour.