Urology Health - What is a CT Scan?


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What is a CT Scan?

Computed axial tomography (also known as "CT scan" or "CAT scan") combines x-rays and computer processing to make very detailed images. It can clearly show tissues and organs. These images can be stored, viewed on a monitor, or printed on film.

A CT scan can show differences between solids and liquids. It helps find tumors, masses, stones, and cysts. Sometimes special dyes are injected to make the images sharper. The 3-D images produced by CT scans can also help a surgeon plan for surgery.

A CT scan works by using very small, controlled beams of x-rays that pass through your body as they spin in a circle around you. Thousands of x-ray images are collected within one scan. This data is collected in seconds, with no gap between the images. The computer puts the data together to produce complete and detailed pictures. The computer is used to make a 3-D picture of your body.


This test is done in a hospital or radiology office by a radiologist or technician. You'll lie on a narrow table that slides into the center of the scanner. Dye may be injected into a vein in your hand or arm.

The technician will let you know if you’ll need to change position, lie still, or hold your breath. When the test is done, you can go back to your normal activities.


CT is considered mostly safe. The major risk is a reaction to the iodine-based dye.

Minor reactions include:

  • Hot flashes
  • Nausea
  • Vomiting

These can often be treated well with antihistamines.

In very rare cases, more severe problems can occur. These can include:

  • Trouble breathing
  • Low blood pressure
  • Swelling of the mouth or throat
  • Heart attack

More Information

The amount of radiation used in this test is rather low. Women who are (or may be) pregnant should tell their urologist before the test.

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