Virtual colonoscopy or computed tomographic colonography (CTC)

Status: Decision completed

Policy context

CTC has been proposed as a less invasive alternative to conventional colonoscopy to screen for colorectal cancer, with the potential to induce more individuals to get screened. The issues are over concerns about safety, efficacy and cost. The screening would expose individuals to radiation, the accuracy of the imaging test is unknown, there is a need for additional procedures to remove and findings, and the cost of the test is greater and may need to be done more often.

Primary criteria ranking

  • Safety = Med
  • Efficacy = High
  • Cost = Med


Colon cancer is the nation's second leading cause of cancer deaths, and an estimated 52,000 people will die from it this year. Screening can save lives by finding growths before they turn cancerous. Colonoscopies, considered the gold standard test, are recommended every 10 years for everyone over 50 and more frequently after polyps are found or for high risk individuals. Only about one-half the population gets the recommended screening.

Traditional colonoscopy involves taking laxatives to cleanse the bowel and sedation for the procedure. A tube is inserted in the rectum and snaked through the large intestines by a gastroenterologist. Generally, any polyps that are spotted, regardless of size, are taken out in the process. CTC involves taking laxatives to cleanse the bowel and inflating the colon (with air or gas using a small tube inserted in the rectum). A CT scanner is used to take a series of X-rays of the colon and a computer to create a 3-D view. A radiologist then checks the images for suspicious polyps. If any polyps need to be removed, the patient must then have a regular colonoscopy.