Computed Tomography (CT)
Understanding CT
The CT scan, or Computed Tomography scan, is an advanced diagnostic test that uses X-rays, a special scanner and a computer to produce detailed images of a specific area of your body. These images, when studied in sequence, can give your physician a 3-D view of your body to result in a more accurate diagnosis.
How CT Scanners Work
The scanner is made up of a ring containing an X-ray tube and receptors. The region of interest will be placed within the ring and the X-ray tube rotates around you. With each rotation, the tube sends X-rays, and the receptors measure the amount of X-rays absorbed during each rotation of the ring. The computer then transforms these measurements into a visual image. This image, or slice, is viewed on a video screen during the exam and later converted to digital or print media for the radiologist or your doctor to study.
Preparing for Your CT Test
Your physician will provide you with specific instructions depending on the part of your body being scanned. Some examinations require a special diet or medication before the exam.
- Tell your doctor and the technologist if you are pregnant, think you might be or are breastfeeding.
- Tell your doctor and the technologist if you are allergic to, or have ever had any reaction to iodine, contrast media or shellfish.
- Wear comfortable, loose-fitting clothing, but you may be asked to change into a hospital gown.
- You may be asked to remove hairpins, earrings and other objects that may interfere with the CT scan.
Understanding Contrast Media
Certain types of CT scans require the use of contrast media. Contrast media are substances given orally and/or intravenously to highlight certain areas of your body. The intravenous contrast may cause you to feel warm, and you may experience a metallic taste in your mouth. Tell your technologist immediately if you begin to itch, feel short of breath or experience discomfort.
The Actual Test
Your technologist will position you on the CT table, and then the table will slide into the ring of the scanner. Your technologist will conduct the test from an adjacent room. You will be able to communicate with your technologist through a patient intercom system during the entire exam.
Try to remain relaxed and as still as possible. You may be asked to hold your breath for short periods of time as images are acquired. Try to be consistent in the amount of air you breathe each time. You may hear the sounds of the gears and motors from the CT ring; this is normal. Most CT exams are completed within 20 minutes.
A radiologist will interpret your exam and the results will be sent to your physician as soon as possible.
