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Computed Axial Tomography

What you should know

A computed axial tomography (tuh-mah-gruh-fee) scan is also called a "CT" or "CAT" scan. It is a painless test that takes pictures of the inside of the body. CT scans are especially good for showing bone, soft tissue, and blood vessels. These pictures are taken in slices. Each picture or "slice" shows only a few layers of body tissue at a time. By taking pictures like this, caregivers can more easily find and see problems in the body. This test usually takes about 15 to 30 minutes. Newer CT machines can do a test in only a few minutes.

Care Agreement

You have the right to help plan your care. To help with this plan, you must learn about your health condition and how it may be treated. You can then discuss treatment options with your caregivers. Work with them to decide what care may be used to treat you. You always have the right to refuse treatment.


  • A CT scan is a painless test with few risks. Ask your caregiver if you are worried or have questions about your test. A CT scan exposes you to radiation but the benefits of having the test outweigh the risks. A lead apron can be put over your abdomen to lessen exposure unless the scan is of your pelvis or abdomen. Women who are pregnant or think they might be should not have this test. And, mothers who are nursing should not breastfeed their baby for 24 hours after receiving x-ray dye.
  • Some patients can have a reaction to the x-ray dye because it has iodine. This reaction may be mild like itching and hives or more severe like trouble breathing. Tell your caregiver if you have any unusual symptoms. You are able to talk to your caregiver at all times during the scan.
  • Some diabetic medicines should not be restarted for 2 days after receiving x-ray dye. Caregivers may order kidney tests before having you restart those diabetic medicines. This is to prevent kidney damage and a serious reaction called lactic acidosis. Metformin (Glucophage®) is one of these medicines.

Getting Ready


Do not eat solid food 4 to 8 hours before the test if you're getting dye or sedative (seh-duh-tiv) medicine during the test. You may have clear liquids up to 2 hours before exam. Clear liquids include water, black coffee or tea, apple juice, clear soda, or clear broth. Follow any other special instructions from your caregiver.


Do not wear any jewelry including rings, earrings, necklaces, or watches.


  • Informed Consent: You have the right to understand your health problem in words you can understand. You should be told what tests, treatments, or procedures may be done to treat your problem. Your doctor should also tell you about the risks and benefits of each treatment. You may be asked to sign a consent form that gives caregivers permission to do certain tests, treatments, or procedures. If you are unable to give your consent, someone who has permission can sign this form for you. A consent form is a legal piece of paper that tells exactly what will be done to you. Before giving your consent, make sure all your questions have been answered so that you understand what may happen.
  • Screening Sheet: You will be asked to fill out a screening sheet. Tell your caregiver if:
    • You think you are pregnant. The CT scan exposes you and your unborn baby to x-rays that can cause birth defects.
    • You are allergic to any foods or medicines. You must tell your caregiver if you are allergic to shellfish or iodine. This is important since you may get x-ray dye or contrast liquid during the test.
    • You are taking any diabetic medications. This is important since x-ray dye can be harmful with some diabetic medicines. Metformin (Glucophage®) is one of these medicines.


Bring a family member or friend with you if you need to wait for test results. They can help support you during and after the test. They can also drive you home if you have sedative medicine during the test.

Time of Test:

  • Write down the correct date, time, and location of your procedure.


What Will Happen:

You may be asked to change into a hospital gown and to remove all jewelry, earrings, or other metal objects. Caregivers will help you lie down on the CT scan table. The body part being tested may be kept in place with a cradle or straps to hold it very still. You must lie very still during the test. The CT scan pictures may not be clear if you move.

  • An x-ray dye or contrast liquid may be used to help your body parts show up better in the pictures. You may need to drink the x-ray dye as a liquid about an hour before your CT scan is done. It takes this long for the liquid to coat your stomach and intestines. Or, you may be given the x-ray dye in an IV tube that is put into your vein.
  • Your caregiver will then take your vital signs during the test. This includes taking your temperature, blood pressure, pulse (counting the heartbeat), respirations (counting your breaths) and pulse oximetry (oks-ih-mih-tree).
  • During the test the table moves into the ring of the machine. You may hear clicking sounds as the ring moves to take the pictures. The table may keep moving farther into the ring during the test. Do not be afraid, this test does not hurt.
    Computerized Axial Tomography Scan

Waiting Room:

This is a room where your family can wait until your CT scan is done. If your family leaves, ask them to leave a phone number where they can be reached. When it is time for you to go home, someone will need to drive you home if you had sedative medicine. Do not drive home alone.

Contact a caregiver if

  • You cannot make it to your CT scan appointment on time.
  • You have questions or concerns about having a CT scan.

The above information is an educational aid only. It is not intended as medical advice for individual conditions or treatments. Talk to your doctor, nurse or pharmacist before following any medical regimen to see if it is safe and effective for you.

Further information

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.