The radiation from CT scans is so great that children who have them run a far higher risk of developing cancer for the remainder of their life.
Researchers reckon the risk remains high for 58 years after having the scan, but they admit it could be for longer.
Around 1 million CT scans are performed on children aged five years or younger every year in the US, often for diagnosing cancer.
But the scans emit ionizing radiation, a known carcinogen. To see if the scans did cause cancer, researchers from the University of Rochester Medical Centre tracked 1,303 people who, as small children, had CT scans between 1953 and 1987. None of the children had cancer, but had the scan to check for an enlarged thymus that, at the time, was believed to be a health problem.
Over the years, and up to 2008, 50 of the group developed thyroid cancer compared with just 13 of their siblings who had not been scanned.
(Source: Radiation Research, 2010; 174: 753-62).
