The latest state-of-the-art technique, known as CTCA (computed tomography coronary angiography), can dramatically increase the risk of cancer, researchers have announced this week.
It was designed as the safe alternative to coronary angiography, which comes with a 1.7 per cent rate of major complications, but doctors have always believed that its radiation levels could cause fatal cancers.
The Food and Drug Administration has estimated that a standard 10-mSv scan will cause one fatal cancer in every 2000 scans. This suggests that up to 30,000 people every year develop cancer following a scan.
Now researchers from Columbia University in New York have put more shape to these general estimates, and have found that the most 'at risk' groups are women, the young, and those who have multiple scans.
At its worst, the risk is around 1 per cent in young people who are scanned, they discovered.
Doctors, and health watchdogs, have recognised the risk for years - and yet the patient is rarely informed. Around 150,000 CT scans are given every day in the USA alone, and yet patients are giving their consent without being told of the cancer risks.
It's an ethical issue that doesn't seem to trouble doctors overmuch. Their view is that the general 'background' risk of getting cancer is one in five, so what harm is there in a little 'top-up' of a scan?
(Source: Journal of the American Medical Association, 2007; 298: 317-23).