CAT Scan (cont.)
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.
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.
In this Article
- CT scan facts
- What is a CT scan?
- Why are CT scans performed?
- Are there risks in obtaining a CT scan?
- How does a patient prepare for CT scanning, and how is it performed?
- Find a local Doctor in your town
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.
Braunwald, Eugene, et al. Harrisons's Principles of Internal Medicine. 15th ed. McGraw-Hill, 2001.
Tramma, Simone, et al. "Helical CT Scans and Lung Cancer Screening." CDC NIOSH Science Blog. 10 Jan. 2011. <http://blogs.cdc.gov/niosh-science-blog/2011/01/helical/>.
Previous editor: William C. Shiel Jr., MD, FACP, FACR
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