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 give 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 scanned 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 “stop 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.
What is NOT true of a CAT scan?

A．It is safer than regular X rays.

B．It makes use of computer techniques.

C．It can stop the action of an organ for a short time.

D．It gives clear pictures of active, moving body parts.

The underlined words “a foreign object”（Para 3）most probably refer to     .

A．a badly injured part inside the body

B．a new thing that is unknown to the doctor

C．a strange organ that has grown in the body

D．an object that gets inside the body by chance

What is the special use of the latest CAT scanners?

A．It provides clear photos of moving organs.

B．It can take 3-dimension（三维）pictures of inside organs.

C．It won’t cause serious skin burns, cancer or other damage to the body.

D．It helps to find out what is going on inside a person’s body without opening it up.

We can infer from this passage that     .

A．patients in front of CAT may suffer from a bit of radiation

B．doctors need no opening-up of the body with CAT scanners

C．CAT scanners are more expensive than regular X-ray machines

D．CAT scanners can take photos of either the whole body or a part of it

The best title of this passage might be        .

A．the Newest Medical Invention

B．New X-ray Machine to Save Lives

C．How to Avoid the Damage of X Rays

D．Advantages and Disadvantages of CAT Scanners