When Eric Rowe turned 50, the question was not whether the Washington lawyer would be screened for colon cancer, but how. His wife had undergone a colonoscopy, the gold-standard exam that costs about $1,500. Rowe’s internist recommended an alternative that was less invasive and expensive: a virtual colonoscopy, which uses three-dimensional images from a CT scan to detect benign polyps or cancers.

“It sounded good to me,” said Rowe, pleased that he could schedule the $800 procedure for 7.45 am. Unlike standard colonoscopy, generally performed under anaesthesia, in which a long, flexible scope is inserted into the rectum and snaked through the large intestine to find and snip out polyps, the new procedure doesn’t require a ride home or a day off.

Invented 16 years ago by a radiologist, virtual colonoscopy has become an increasingly popular alternative to standard, or optical, colonoscopy typically performed by a gastroenterologist. Initially regarded as a high-tech novelty, the new procedure has received key endorsements as a first-line screening test from influential medical groups after several studies found it to be effective at finding large polyps. Like other mass screening tests, including mammography, the overarching question is whether the benefits of virtual colonoscopy outweigh the risks.

Its supporters tout virtual colonoscopy as a more palatable alternative that has the potential to boost low rates of screening. Colon cancer can be prevented — or even cured — if detected early. “This is a really good test that’s going to find way more cancer than optical colonoscopy,” said Mark Klein of Washington Radiology Associates, who has performed more than 1,200 virtual colonoscopies since 2002. “Is it perfect? No. But no test is.”

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