CT Scan: What Is It and How to Prepare for the Procedure

Learn More About How You Can Get Ready for Your Upcoming CT Scan

Doctor running CT scan from control room. Credit: Morsa Images / Getty Images

The medical term, Computed Tomography scan, is the long version for a CT scan, a special type of x-ray which is also sometimes referred to as a CAT scan. The images produced by a CT scan are very detailed cross-sectional pictures of the body that allow for a look at tissues and organs inside the body. It can help diagnose conditions such as:

  • broken bones
  • tumors
  • blood clots
  • heart disease
  • head injury
  • to see whether cancer is responding to treatment
  • abdominal/pelvic pathology such as infectious complications/obstructions

What to Expect

A technologist is required to operate the large, box-like machine with a short tunnel in the center. CT scanners typically have an examination table that slides in and out of the tunnel, while x-ray tubes and electronic x-ray detectors rotate around you.

The technician will be operating the scanner and monitors in an adjoining control room, with the ability to maintain visual contact through a window and hear or talk to you over a speaker and microphone.

For a CT scan, you will lie on the examination table while it slowly moves through the center of the machine. The procedure is not painful but lying still on the table during the scan may be a little uncomfortable. The scan may take 15 minutes to 1 hour to complete, depending on the type of CT scanner being used and the size of the area being scanned.

Some CT exams may require the use of a contrast material to enhance visibility in the area of the body being examined.

Contrast material may be swallowed, available through an intravenous line (IV) or, rarely, administered by enema, depending on the type of exam.

During a CT Scan

Any motion, whether breathing or body movements, can lead to a loss of image quality and blurring. For this reason you may be asked to hold your breath during the CT scan.

Modern scanners can scan through large sections of the body in less than a few minutes and even faster in children. This is helpful to all patients but especially for the critically ill, the old and for children, since it can be difficult to remain still. Many scanners are fast enough that children do not require sedation, but in special cases, sedation may be needed for those who cannot hold still.

There is a small amount of radiation exposure associated with CT scans. For children, the scanner is adjusted to their size so that the scan can be done with low-dose technique.

Once the examination is complete, you will have to wait until the technologist verifies the image quality of your scans for an accurate interpretation.

Finally, your CT image results are reviewed and analyzed by a trained radiologist who will send an official report to your doctor. Your doctor will then discuss your results with you.

How to Prepare

Even though you may be asked to change into a gown once you show up for your procedure, consider wearing comfortable and loose-fit clothing.

You will be given instructions on removing the following objects as these may affect CT images:

  • Metal objects, including jewelry, eyeglasses, dentures and hairpins
  • Hearing aids and removable dental work
  • Bras containing metal underwire
  • Remove any piercings, if possible

If contrast material is used during your procedure, you will be asked not to eat or drink anything for a few hours beforehand.

You will want to contact the doctor that referred you for the CT scan and let them know the following:

  • If you are on any medication
  • If you have any allergies to food coloring or dyes, as contrast material may contain such ingredients. Your doctor may prescribe medications (usually steroids) to reduce the risk of allergic reactions, which will need to be taken about 12 hours before contrast material. Contact your doctor well before the exact time of your CT scam to avoid any unnecessary delays.
  • Of any recent illnesses or medical conditions
  • Of any history of heart disease, asthma, diabetes, kidney disease or thyroid problems (these conditions may increase the risk of an unusual adverse effect).
  • Women should always inform their physician and the CT technologist if there is any possibility that they may be pregnant.


Radiological Society of North America. Computed Tomography (CT) - Body. Accessed 4 March 2016.

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