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How A CT Scan Works

Posted Aug 27 2008 8:33am
A CT (computer tomography) scan is one of several diagnostic procedures that helps give doctors a better idea of what is going on inside your body. Unlike an X-ray, which only takes one image of your body, a CT scan takes a series of images. Each image is a cross section of a portion of your body, and when all the cross sections are put together with the help of the computer, they provide a much more in-depth look.



Example of an image "slice" from a CT scan of the head.





The advantage to having a CT scan done rather than an X-ray, is that a CT can "see" more features that would not be visible on a standard X-ray. For example, organs and tissues show up more readily on a CT scan. Additionally, a CT scan exposes the patient to less radiation than an X-ray, thereby making it a safer procedure. This is especially important since many cystic fibrosis patients will undergo dozens of X-rays in the course of a lifetime of treatment.

But how does it work?

The CT scanner device looks like a large doughnut that can rotate and tilt. The patient lies on a narrow table that is slowly moved through the center of the ring. For the most part, the procedure is not altogether uncomfortable or confining.




The CT scan works in the following way: As the patient table slides toward the center of the ring, the scanner begins rotating. This is how it takes pictures of the body from every angle. After each series of pictures, the table moves a fraction of an inch as the scanner takes another series of pictures. Within minutes, the entire procedure is over, and the technicians have acquired an accurate cross-section image of a portion of the patient's body.

When are CT scans performed?

Computer tomography is a very powerful tool that can be used to assess nearly every portion of the body. CT scans are used when X-rays alone cannot provide an image with the level of detail required for the physician to make a diagnosis. For cystic fibrosis patients, CT scans are most often done to assess the need for sinus surgery. A doctor may also request a CT scan to look for abnormalities on the pancreas, gall bladder, or liver.

For more information about CT scans, the following links are useful:

CT Scan Procedure requiring contrast

Common Questions about CT Scans
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