CT Scan (Computerized Tomography, CAT Scan)

  • Medical Author:
    Melissa Conrad Stöppler, MD

    Melissa Conrad Stöppler, MD, is a U.S. board-certified Anatomic Pathologist with subspecialty training in the fields of Experimental and Molecular Pathology. Dr. Stöppler's educational background includes a BA with Highest Distinction from the University of Virginia and an MD from the University of North Carolina. She completed residency training in Anatomic Pathology at Georgetown University followed by subspecialty fellowship training in molecular diagnostics and experimental pathology.

  • Medical Editor: Charles Patrick Davis, MD, PhD
    Charles Patrick Davis, MD, PhD

    Charles Patrick Davis, MD, PhD

    Dr. Charles "Pat" Davis, MD, PhD, is a board certified Emergency Medicine doctor who currently practices as a consultant and staff member for hospitals. He has a PhD in Microbiology (UT at Austin), and the MD (Univ. Texas Medical Branch, Galveston). He is a Clinical Professor (retired) in the Division of Emergency Medicine, UT Health Science Center at San Antonio, and has been the Chief of Emergency Medicine at UT Medical Branch and at UTHSCSA with over 250 publications.

View the Men's Health Screenings Slideshow

How does a patient prepare for CT scanning, and how is it performed?

In preparation for a CT scan, patients are often asked to avoid food, especially when contrast material is to be used. Contrast material may be injected intravenously, or administered by mouth or by an enema in order to increase the distinction between various organs or areas of the body. Therefore, fluids and food may be restricted for several hours prior to the examination. If the patient has a history of allergy to contrast material (such as iodine), the requesting physician and radiology staff should be notified. All metallic materials and certain clothing around the body are removed because they can interfere with the clarity of the images.

Patients are placed on a movable table, and the table is slipped into the center of a large donut-shaped machine which takes the X-ray images around the body. The actual procedure can take from half an hour to an hour and a half. If specific tests, biopsies, or interventions are performed by the radiologist during CT scanning, additional time and monitoring may be required. It is important during the CT scan procedure that the patient minimizes any body movement by remaining as still and quiet as is possible. This significantly increases the clarity of the X-ray images. The CT scan technologist tells the patient when to breathe or hold his/her breath during scans of the chest and abdomen. If any problems are experienced during the CT scan, the technologist should be informed immediately. The technologist directly watches the patient through an observation window during the procedure, and there is an intercom system in the room for added patient safety.

CT scans have vastly improved the ability of doctors to diagnose many diseases earlier in their course and with much less risk than previous methods. Further refinements in CT scan technology continue to evolve which promise even better picture quality and patient safety. CT scans known as "spiral" or "helical" CT scans can provide more rapid and accurate visualization of internal organs. For example, many trauma centers are using these scans to more rapidly diagnose internal injuries after serious body trauma. High resolution CT scans (HRCT) are used to accurately assess the lungs for inflammation and scarring. CT angiography is a newer technique that allows noninvasive imaging of the coronary arteries. Note that some CT scanners may not be able to accommodate patients that weigh over 400 pounds.

Medically reviewed by a Board-Certified Family Practice Physician REFERENCES:

Braunwald, Eugene, et al. Harrisons's Principles of Internal Medicine. 15th ed. McGraw-Hill, 2010.

FDA.gov. Computed Tomography.

Tramma, Simone, et al. "Helical CT Scans and Lung Cancer Screening." CDC NIOSH Science Blog. 10 Jan. 2011.

Medically Reviewed by a Doctor on 11/6/2015

Subscribe to MedicineNet's Newsletters

Get the latest health and medical information delivered direct to your inbox!

By clicking Submit, I agree to the MedicineNet's Terms & Conditions & Privacy Policy and understand that I may opt out of MedicineNet's subscriptions at any time.

VIEW PATIENT COMMENTS
  • CT Scan - Helped With Your Diagnosis

    Please describe how a CT Scan has helped in your diagnosis.

    Post View 24 Comments
  • CT Scan (Computerized Axial Tomography) - Causes

    What caused you to get a CT scan?

    Post View 8 Comments
  • CT Scan - Experience

    For someone who has never had a CT scan, please describe what the experience is like.

    Post View 5 Comments

Health Solutions From Our Sponsors