CT uses X-rays to perform its work. These X-rays come from an X-ray tube which is placed inside a square machine called the gantry. The part of your body to be scanned goes inside a hole in this gantry.
All parts of the body can be scanned with CT. For each part, there are specific indications or reasons for scanning. Your referring doctor and the consultant radiologist are the best judges of the usefulness of CT scanning in a specific situation and areas.