If a positive decision has been reached on the issue of proton radiation, the next step is staging. Your entire body will be examined for signs of tumors and metastases. A proposal on the correct strategy can only be made on the basis of this investigation--for example, simultaneous irradiation of several targets or a combination therapy--along with a realistic assessment of the prospects for success. The staging examination is completely painless. Your entire body may be subjected to a CT scan in conjunction with a PET (positron emission tomography) scan. Under certain circumstances, a contrast medium will be injected to enhance the quality of the image.
An MRI scan is always the option of choice, because it does not subject the body to radiation. The PET-CT scan, on the other hand, requires an injection of radioactive material with a short half-life. Therefore, it is only used where appropriate.
The image material from the staging examination includes cross-sections of the body at intervals of 5 millimeters, or approximately 360 images. The large number of images allows the diagnostic radiology team to play the images in rapid succession like a film. The technician and physician are very adept at identifying abnormal findings from this "journey through the human body" with remarkable precision.