CT (computed tomography), sometimes called a CAT scan, uses a combination of X-rays and computer technology to produce two-dimensional cross-sectional images (slices) both horizontally and vertically, of the body.
Unlike conventional X-rays, which take a single picture of a part of the body, computed tomography generates multiple X-ray images in a single examination. Despite the large number of images, the total amount of radiation can be less from a CT scan than from some conventional X-ray procedures.
While much information can be obtained from a regular x-ray, a lot of detail about internal organs and other structures is not available. In a CT scan, the x-ray beam moves in a circle around your body. This allows many different views of the same organ or structure and provides much greater detail. The x-ray information is sent to a computer that displays it in two-dimensional form on a computer. While CT scans show the inside of the body in much greater detail than a conventional x-ray, high-resolution CT is available at Franciscan Health when there is a need to see an area in extremely small detail.
CT scans may be done with or without contrast. This “contrast” refers to a substance taken by mouth or injected into an intravenous (IV) line that causes the particular organ or tissue to stand out more clearly.
Preparation before the procedure
Inform your doctor if you think there is a possibility that you are pregnant.
If you have diabetes or kidney disease and/or are taking glucose-lowering medication, talk to your doctor about stopping the medication and proper scheduling of the scan with dialysis, if necessary.
You may be asked to drink oral contrast medication right before the test or four to six hours before the scan.
You may be asked to remove metal objects, jewelry, hearing aids, eyewear and removable dental pieces.
For a more in depth look at this procedure, visit our Health Library page on this topic.