الفهرس 
AnatomyOnly 14 pages are availabe for public view
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Abstract
Colorectal cancer represents the third most frequently diagnosed cancer worldwide, and the second most diagnosed cancer in industrialized western countries (Landis et al, 1998).
More than 95% of colorectal cancers are adenocarcinomas that arise from non malignant but dysplastic adenomas that progress to invasive carcinoma during a period of 10-15 years (Yee et al, 2001).
Early detection and preventive removal of pre-malignant adenomatous polyps are believed to be the most probable reason for the gradual decrease in both incidence and mortality (Winawer et al, 1993).
Computed tomographic (CT) colonography including virtual colonoscopy is a noninvasive rapidly evolving technique that has been shown in some studies to be comparable to conventional colonoscopy for the screening of colorectal cancer. CT colonoscopy technique uses standard helical CT images of the colon and advanced imaging software to produce reformatted two- and three-dimensional rendered views of the entire colo-rectum. Computer rendered three-dimensional images simulate the endoluminal image seen at colonoscopy but in a minimally invasive manner and without the risks associated with sedation of the patient (Hara et al, 1997).