A Cat scan also known as a CT scan is a diagnostic radiology exam. It is used frequently to diagnose soft tissue conditions mainly such as examining your abdominal organs. It is generally considered non-invasive but sometimes they use IV contrast to better visualize what they are looking for.

 You can go to www.wikipedia.org, type in catscan, you will find what you need there. It is a machine that take x-rays of your brain or whatever part of the body that they want the pictures of, but it doesn't use the typical film that they use for a traditional x-ray I didn't do a lot of reading about it so I can't really go into it, but I do think that this will help you out a lot. Good luck.

 Computerized Axial Tomography.  Yes, do Wikipedia.

  series of detailed pictures of areas inside the body, taken from different angles; the pictures are created by a computer linked to an x-ray ...
www.seniormag.com/conditions/cancer/cancerglossary/c.htm