CT Scan

What is CT Scanning?

CT Scanning (computerized tomography), sometimes called CAT scan, uses special X-ray equipment to obtain images from different angles around the body. A computer then processes this information to show body tissues and organs, in cross sectional views called slices.

What are the Benefits of CT Scans?

  • CT scanning is painless, non-invasive and accurate.
  • A diagnosis made with the assistance of CT scans can often eliminate the need for invasive exploratory surgery and surgical biopsy.
  • CT Scanning allows detailed views of many types of tissues including the lung, bones, soft tissues and blood vessels. 

What are the Risks of CT Scans?

  • CT Scanning does involve exposure to radiation, but the benefit of an accurate diagnosis far outweighs the risk.
  • Nursing mothers should wait 24 hours after contrast material injection before resuming breast-feeding.
  • Though uncommon, some people can have adverse reactions to the contrast materials.

What Will the Exam Be Like?

You will lie comfortably on the CT exam table. Pillows to help you hold still and in the proper position may be placed under or around you. The table will move slowly into the CT scanner. You will be alone in the room but the technologist will be in constant communication with you. 

Depending on the exam, a contrast material may be used to enhance the visibility of certain tissue or blood vessels. The contrast material may be injected directly into the bloodstream, swallowed, or administered by enema, depending on the type of exam.

If a contrast material is used, the technologist will ask you whether you have any allergies, especially to iodine, and whether you have a history of diabetes, asthma, a heart condition, kidney or thyroid problems. These conditions may indicate potential problems eliminating the material from your system after the exam.

You may be asked to drink a liquid contrast material to better see the stomach, small bowel and colon. Some find the taste unpleasant but most are able to tolerate it.

Most commonly, the contrast material is injected through a vein in your arm. You may feel a minor sting with the injection and some people feel flushed or sometimes have a metallic taste in their mouth. These are all normal sensations to contrast material and will last no more than a minute or two. In rare instances itching, shortness of breath, or swelling in the throat or other parts of the body may occur. Tell the technologist immediately if you experience these symptoms.

The contrast material will be naturally eliminated within a few hours to a day or two depending on the area examined and the type of contrast material used.

A CT Scan usually takes about 15 to 30 minutes.

What Does the Equipment Look Like?

A CT Scanner has an exam table that can be moved up or down and forward and backward. Inside the machine is an X-ray tube that will move around your body to capture the images.

How Should I Prepare for the Exam?

  • Wear comfortable, loose-fitting clothing for your exam. Metal object can affect the image, so avoid clothing with zippers and snaps.
  • You will be asked to remove anything metallic that might degrade the images, including hairpins, jewelry, eyeglasses, hearing aids and any removable dental work.
  • For some scans your doctor may instruct you not to eat or drink for one or more hours before your exam. 
  • Inform your doctor of any allergies you have to medications.
  • Inform your doctor of any recent i9llnesses or medical conditions.
  • Always inform your doctor and the technologist if you are pregnant or think there is a possibility you may be pregnant.

How Will I Learn the Results?

A radiologist, who is a physician specializing in CT and X-ray examinations, will study your CT scan images. This specialist will analyze your images and report the results to your doctor.

The results of your CT Scan will be made available to you through your designated healthcare provider or practitioner. 


  • Always inform your doctor and the technologist if you are pregnant or think there is a possibility you may be pregnant. 
  • Inform your doctor or the radiologist of any allergies, especially to medications or iodine.
  • Inform the technologist if you are sensitive to latex or other substances.

(This information is intended to serve as a simple guide. It can never replace the conversations with your own doctor. It is not a substitute for professional care.)

(Some information on this page was provided courtesy of The St. John Companies, Inc. PO Box 800460 Santa Clarita, CA 91380))