CT Scan (Computerized Tomography)

A CT or CAT scan is a diagnostic imaging procedure that uses a combination of x-rays and computer technology to produce cross-sectional images (often called slices), both horizontally and vertically, of the body. A CT scan shows detailed images of any part of the body, including the bones, muscles, fat, and organs. CT scans are more detailed than general x-rays.

In computed tomography, the x-ray beam moves in a circle around the body. This allows many different views of the same organ or structure, and provides much greater detail. The x-ray information is sent to a computer that interprets the x-ray data and displays it in 2-dimensional form on a monitor. While many images are taken during a CT scan, in many cases, the patient receives less radiation exposure than with a single standard x-ray.

CT scans may be done with or without contrast. “Contrast” refers to a substance taken by mouth or injected into an intravenous (IV) line that causes the particular organ or tissue under study to be seen more clearly. Contrast examinations may require you to fast for a certain period of time before the procedure. Your physician will notify you of this prior to the procedure.

You will need to let your physician know if you have ever had a reaction to any contrast dye, or if you are allergic to iodine or seafood. If you are pregnant or think you may be pregnant, you should notify your physician. If you are claustrophobic or tend to become anxious easily, tell your physician ahead of time, as he/she may prescribe a mild sedative for you before the procedure to make you more comfortable. It will be necessary for you to remain still and quiet during the procedure, which may last 30 to 60 minutes.

Before the CT Scan
Tell the radiologist if you are:

  • Allergic to iodine or other materials
  • Pregnant
  • Claustrophobic and possibly unable to lie still while inside the scanning machine

What to Expect During a CT-Scan
CT scans can be performed on an outpatient basis, unless they are part of a patient’s inpatient care. Generally, CT scans follow this process:

  • When you arrive for the CT scan, you will be asked to remove any clothing, jewelry, or other objects that may interfere with the scan.
  • If your procedure is to be done with contrast, an intravenous (IV) line will be started in the hand or arm for injection of the contrast medication. For oral contrast, you will be given medication to swallow.
  • You will lie on a scan table that slides into a large, circular opening of the scanning machine.
  • The CT staff will be in another room where the scanner controls are located. Speakers inside the scanner will enable the staff to communicate with you. You will have a call bell so that you can let the staff know if you have any problems during the procedure.
  • As the scanner begins to rotate around you, low-dosage x-rays pass through your body for short amounts of time.
  • The x-rays absorbed by the body’s tissues are detected by the scanner and transmitted to the computer.
  • The computer transforms the information into an image to be interpreted by the radiologist.
  • It is very important that you remain very still during the procedure.
  • The technologist will be watching you at all times and will be in constant communication.
  • You may be asked to wait for a short period of time while the radiologist examines the scans to make sure they are clear.

If the scans are not clear enough to obtain adequate information, you may need to have additional scans performed.