How can you find out what is going on inside a person’s  body without opening the patient’s body up? Regular X rays can show a lot. CAT scans can show even more. They can g ive a complete view of body organs.What is a CAT scan? CAT stands for a kind of machine. It is a special X-ray machine that gets a 360-degree picture of a small area of a patient’s body. Doctors use X rays to study and determine diseases and injuries within the body, X rays can find a foreign object inside the body or take pictures of some inside organs to be X-rayed. A CAT scanner, however, uses a group of X rays to give a cross-sectional（横截面）view of a specific part of the body. A fine group of X rays is scann  ed across the body and around the patient from many different directions. A computer studies the information from each direction and produces a clear cross-sectional picture on a screen. This picture is then photographed for later use. Several cross sections, taken one after another, can give clear “photos” of the entire body or of any body organs. The latest CAT scanners can even give clear pictures of active, moving organs, just as a fast-action camera can “s top the action”, giving clear pictures of what appears unclear to the eye. And because of the 360-degree pictures, CAT scans show clear and complete views of organs in a manner that was once only shown during operation or examination of a dead patient.Frequent appearance before X rays can cause skin burns, cancer or other damage to the body. Yet CAT scans actually don’t cause the patient to more radiation than regular X rays do. CAT scans can also be done without getting something harmful into the patient, so they are less risky than regular X rays. CAT scans provide exact, detailed information. They can quickly find such a thing as bleeding inside the brain. They are helping to save lives. 小题1:What is NOT true of a CAT scan?
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