CT Scan

What is a CT scan?

A CT scan, also called computed tomography or CAT scan, is a special type of X-ray test. X-rays are taken from different angles and a computer puts the X-ray images together to create cross-sectional views of the body.

A CT scan provides detailed pictures to:

• Help your healthcare provider diagnose a problem.
• Check your health after a treatment, such as surgery or chemotherapy.

When is it used?

CT scans are used when your healthcare provider needs more detailed information than regular X-rays can give. CT scans can show bone, muscle, fat, lymph nodes, organs, and blood vessels in detail. For example, a CT scan may be used to:

• Check for swelling or bleeding in the brain after a head injury.
• Look for signs of appendicitis.
• Help your healthcare provider guide a needle or catheter into the correct place in the body.

How do I prepare for this test?

• For some CT scans no special preparation is necessary. For others you may have special directions about what you should eat and drink before the test. Follow any instructions your healthcare provider may give you.
• You may need to swallow a special liquid (contrast dye) several hours before the scan.
• You should wear comfortable clothing that has no metal fastenings like zippers or hooks. Leave your watch and jewelry at home.
• Tell your provider if you have had any kidney problems or reactions to iodine-containing foods or chemicals, such as seafood or X-ray contrast dye. (Contrast dye, which contains iodine, is used for some CT scans.)
• Tell your provider if you are or think you may be pregnant.
• Tell your provider if you are afraid of enclosed spaces. Your provider may prescribe medicine to help you relax.
• Ask any questions you have before the procedure. You should understand what your healthcare provider is going to do. You have the right to make decisions about your healthcare and to give permission for any tests or procedures.

What happens during the test?

CT scans can be done in either a hospital or mobile unit.

You will lie down on a moving table, which will slide into a tunnel-like scanning machine. Inside the scanner, multiple X-ray beams are passed very quickly through your body at different angles. Images of your body can be seen on a TV screen and prepared for your healthcare provider to examine later.

A solution of contrast dye may be injected into a vein, or you may be asked to swallow a dye solution. The dye allows the scanner to show abnormal areas as the dye passes through your body. The dye may make you feel warm. Your face may get flushed and you may get a headache or have a salty taste in the mouth. In rare cases, the dye can cause nausea and vomiting.

Scans may last 15 to 90 minutes. They are painless, but you may get uncomfortable from lying in the scanner if the scan takes more than a few minutes. Because of the small, enclosed space, some people get anxious. If you start feeling panicky or are having other problems, the scan may be stopped. Your healthcare provider may recommend a mild sedative to help you relax before and during the scan.

What happens after the test?

Usually, you can go home soon after the test.

If you were given dye for the scan, drinking a lot of fluids after the scan helps your body get rid of the dye. In rare cases some people have an allergic reaction to the dye. Most reactions happen right away, but you could have a delayed reaction.

Ask your healthcare provider:

• how and when you will hear the test results
• what symptoms or problems you should watch for and what to do if you have them

What are the risks of this test?

Your healthcare provider will explain the procedure and any risks. Some possible risks include:

• CT scans expose the body to more radiation than a regular X-ray. The amount of radiation depends on the size of the area being scanned. Exposure to radiation can be dangerous if you are exposed to it often or in large amounts. If you have a medical problem that requires repeated CT scans, you should ask your healthcare provider about how much radiation you are being exposed to and whether you can decrease the number of CT scans you need.
• In rare cases you may have an allergic reaction to medicines used during the procedure.
• If you are pregnant, there is a risk the X-rays will hurt the baby with the X-rays.

There is risk with every treatment or procedure. Ask your healthcare provider how these risks apply to you. Be sure to discuss any other questions or concerns that you may have.