Newer screening tests for colorectal cancer include computed tomography, colonography (virtual colonoscopy), and stool tests that use DNA-based technology. Colonography takes about 10 minutes and does not require sedation, but patients must take laxatives before the test, on regular colonoscopy, and it involves exposure to radiation. Abnormal results as for virtual colonoscopy must be followed up with regular colonoscopy. The DNA-based stool test is more expensive than FOBT but might be more accurate.