Virtual colonoscopy is a medical imaging procedure, which uses computed tomography (CT), sometimes called a CAT scan, and advanced computer software to produce two- and three-dimensional images of the colon that can be viewed on a video screen.
The major reason for performing virtual colonoscopy is to screen for polyps or cancers in the large intestine. Polyps are growths that arise from the inner lining of the intestine. Some polyps may grow and turn into cancers. The goal of screening with colonoscopy is to find these growths in their early stages, so that they can be removed before cancer has had a chance to develop.
Most physicians agree that everyone older than 50 years should be screened for polyps every seven to 10 years. The American Cancer Society recommends virtual colonoscopy screening every 5 years.
Individuals at increased risk or with a family history of colon cancer may start screening at age 40 or younger and may be screened at shorter intervals (for example, every five years). Risk factors for the disease include a history of polyps, a family history of colon cancer, or inflammatory bowel diseases, such as Crohn's disease or ulcerative colitis.