CT scans in childhood have been shown to triple the risk of developing brain cancer or leukaemia, a new study suggests.
The work from scientists at Newcastle University analysed the medical records of patients aged under the age of 21 who had CT scans at a range of British hospitals during 1985 and 2002.
Dr Mark Pearce, an epidemiologist who led the study, said that despite the increased risks, the use of CT scans outweighed the risks in many scenarios.
"Doses have come down dramatically over time - but we need to do more to reduce them. This should be a priority for the clinical community and manufacturers," he added.
UK regulations state that CT scans should only be done when there is clinical justification - and the researchers believe their report supports this.
The technology works by rotating an X-ray tube around person's body to produce detailed images of internal organs and other parts of the body.