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What Happens During a CT Scan?

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Updated April 17, 2014

A CT scan

The patient lies on a table that moves into the CT scanner

Photo © A.D.A.M.
Question: What Happens During a CT Scan?
Answer: A computed tomography (CT) scan is a special type of x-ray that creates very detailed cross-sectional pictures of the body. For a CT scan, you will lie on a table that slowly moves through the center of a large x-ray machine. During the scan, the x-ray machine may make soft buzzing, clicking and whirring sounds. Before the scan begins, you may swallow dye, it may be injected into your vein or it may be given as an enema (through a tube into the rectum and lower intestine) to help make clearer pictures.

During a spiral (helical) CT scan, the x-ray machine rotates in a spiral pattern around the table as it takes x-ray images. Spiral CT scans are usually completed much faster than other CT scans.

A CT scan is not painful but lying still on the table during the procedure may be a little uncomfortable. If you have a hard time lying still or are anxious about the CT scan, sedative medication may be given prior to the test to relax you. The scan may take a few minutes to one hour to complete, depending upon the size of the area being scanned.

Metal objects, including jewelry, eyeglasses, dentures and hairpins, may affect the CT images and should be left at home or removed prior to your exam. You may also be asked to remove hearing aids and removable dental work. Women who may be pregnant should inform their doctor or the CT technologist prior to having a CT scan.

Sources:

"CT Scans." Medline Plus. 22 Jan 2009. U.S. National Library of Medicine. 28 Jan 2009

"Computed Tomography (CT): Questions and Answers." NCI Fact Sheet. 08 Sep 2003. National Cancer Institute. 28 Jan 2009

"CT - Head." Radiology Info. 20 Aug 2008. Radiological Society of North America. 28 Jan 2009

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