A CAT scan machine, also know as a CT scan machine, detects abnormal problems in your body by taking pictures of the inside. You lay on a table and the technician moves the table until the part that you need to take a picture of reaches the camera which is in the big circle. Any part that does not need to be in the CAT scan stays out of the circle.This machine can detect abnormal brain problems or abnormal stomach problems. It's very big, and you may think it may hurt you, but it won't. All it will do is take pictures of the inside of your body.