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Computed Axial Tomography
What is it?
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.
Why do I need a CT scan?
The pictures made during a CT scan help caregivers learn more about the cause of your health problem. A CT scan can be used to help caregivers learn more about bleeding, tumors (lumps), or blood clots. The test can also look at infection or bone and soft tissue injury. Or, it can be used for biopsy testing (getting a tissue sample through a needle).
How does the CT scan work?
- The CT scan machine is large and round. It has a table in the center of a donut-shaped scanner. The machine is usually in a room by itself. Your caregiver sits behind a window during the CT scan. From this spot, the caregiver can talk to you during your scan.
- A CT scan uses a fan-like beam of x-rays that pass through the part of the body being x-rayed. The CT scan is different than regular x-rays that make pictures of the shadows cast by body images. CT scans take pictures in "slices" of the body and head. The pictures show up on a computer screen. The pictures can be made into hard copies that can be taken or sent to your caregiver.
What happens during the CT scan?
Wear comfortable clothing without metal zippers or snaps. Remove anything that might interfere with the CT scan pictures such as eyeglasses, earrings, necklaces, or hairpins. You may be asked to fill out a screening sheet when you arrive at the radiology department. This asks questions about allergies, if you could be pregnant, what medical problems you have and medicines you take. Caregivers may also need to know if you have ever had a reaction to x-ray dye. These questions help caregivers decide if it is OK for you to have a CT scan. X-rays can hurt an unborn baby so be sure to tell caregivers if you might be pregnant.
- 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 a liquid such as barium if you are having an abdominal (belly) or pelvis CT scan. You will have to wait about an hour after drinking the contrast liquid before your CT scan can be 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. When the x-ray dye is put into your vein, you may feel warm or flushed. You may have a metal or salty taste in their mouth or you may feel sick to your stomach. Tell your caregiver if you feel like you are going to vomit (throw up). This only lasts 1 to 2 minutes. People who are allergic to shellfish (lobster, crab, or shrimp) or have had an allergic reaction to x-ray dye may be allergic to this x-ray dye. Caregivers take special precautions for your safety if you have these allergies.
- 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).
- To take your blood pressure, a cuff is put on your arm and tightened. The cuff is attached to a machine, which gives your blood pressure reading.
- Caregivers may listen to your heart and lungs by using a stethoscope (steth-uh-skop).
- The pulse oximeter machine tells how much oxygen is in your blood. A cord with a clip or sticky strip is put on your ear, finger, or toe and hooked to the machine. Caregivers use this machine to see if you need more oxygen.
- You may be asked to put on a gown and then caregivers help you lie down on the CT scan table. You must lie still while the CT scan is being done so the pictures are clear. The body part being tested may be kept in place with a cradle or straps to hold it very still. 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.
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.
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