A CT scan is a type of x-ray process that can make very sharp, detailed pictures of organs and bones. The CT scanner is linked to a computer. The scanner rotates around the patient, taking pictures of one thin slice of tissue after another. The pictures are viewed on a computer screen.

CT stands for "computed tomography." Some people call this test a "CAT" scan.

Learning more about CT scans can help you prepare your child for this test.

Why is a CT scan done?
A CT scan is a quick and easy way to diagnose many different injuries and diseases, including:

• Head injuries
• Cancer
• Infections such as appendicitis
• Bowel and bladder problems
• Lung diseases
• Broken bones
• Internal injuries
• Birth defects

A CT scan can be done on any part of the body.

How it is done?
For a CT scan, your child will lie on a narrow table. A technician may use pillows and straps to hold your child's body in the right position for the scan.

A fluid called contrast dye may be used to help different organs show up better in the pictures. The contrast dye may be given as a shot, a drink or an enema.

When the child is correctly positioned, the table will move through a hole in the middle of a large machine that looks like a big white doughnut. This machine holds the scanner. As the table passes through the hole, the scanner circles around the body and takes pictures from all sides.

It's important for the child to be still. Moving during the test could make the pictures blurry. If your child is too young or agitated to lie still, the doctor may give your child a sedative. This will help him or her relax or sleep during the test.

You may be able to stay in the room with your child during the scan. You will need to wear a lead apron to protect you from radiation. If there is any chance you may be pregnant, you should not stay in the room.

How should I prepare my child for a CT scan?
Tell your child what will happen during the test.

• You can reassure your child that the test is painless and it will only take a few minutes.
• During the test, the scanner may make some buzzing and clicking sounds, but it won't touch your child.
• If your child gets a shot of contrast dye, it may sting a little. If he or she has to drink the dye, it may taste funny and cause a warm feeling. An enema may cause a full feeling.

If your child will be sedated or given contrast material, he or she may not be able to eat or drink anything for a few hours before the CT scan. The doctor will give you instructions about how to prepare.

Metal objects can affect the pictures, so remove items such as rings, watches, earrings, eyeglasses or hairpins before the test.

What are the risks of a CT scan?
When needed, a CT scan is considered a safe, fast and accurate test. However, it does have some potential risks:

• Future cancer as a result of the radiation used in CT scans. Because of this risk, CT scans are avoided in children unless they are essential for diagnosis.
• Complications from sedation or anesthesia.
• An allergic reaction to the contrast material (rare).

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External Sources Hosalkar HS, Wells L. Evaluation of the child. In: Kliegman RM, Behrman RE, Jenson HB, Stanton BF. Nelson Textbook of Pediatrics. 18th ed. Philadelphia, PA: Saunders Elsevier; 2007. Accessed July 9, 2008. RadiologyInfo. Children's (pediatric) CT (computed tomography). Accessed July 9, 2008.

This article was reviewed and updated 08-01-2009.