Multiple exposure to radiation from computed tomography scans in children may raise the risk of leukemia and brain tumors a decade later, according to government-funded research published in The Lancet journal.
The additional risk of leukemia or a brain cancer 10 years after a 10-milligray dose of radiation from a CT scan is less than 1 in 10,000, according to an analysis of more than 175,000 patients in Great Britain who received a CT scan between 1985 and 2002 when they were younger than 22. That risk may triple in children after multiple scans accumulate to 60 milligrays, researchers at Newcastle University and the U.S. National Cancer Institute wrote in the journal today.
The use of advanced radiology techniques, which provide more detail than traditional x-rays, is increasing as doctors seek to detect the onset of diseases at an early stage. CT or magnetic resonance imaging scans to observe patients with injuries increased about threefold over the last decade in emergency rooms in the U.S., according to a 2010 Johns Hopkins University study.
“CT scans undoubtedly can be life-saving,” Alan Craft, one of the authors of the study at Newcastle University in northern England, told reporters in London yesterday. “There’s a much greater risk of not doing a CT scan where it’s indicated. Parents should be reassured that this study will push us to be even more circumspect about using it.”
While radiation doses, once limited to a single setting, can now be adjusted according to body weight, the average radiation dose of one CT scan roughly equals the amount needed for 500 chest x-rays, according to the International Atomic Energy Agency.
“Use of CT scans continues to rise, generally with good clinical reasons, so we must redouble our efforts to justify and optimize every CT scan,” Andrew Einstein, assistant professor of medicine in radiology at Columbia University in New York, wrote in a commentary accompanying the Lancet publication.
The research was funded by the U.S. National Cancer Institute and the U.K. Department of Health.
The Image Gently Campaign and the Alliance for Radiation Safety in Pediatric Imaging, based in Cincinnati and funded by the Society for Pediatric Radiology and other founding organizations, is pushing for lower radiation doses in children.
In developing countries, guidelines are also needed to reduce the number of unnecessary CT tests in children, the IAEA said in a statement yesterday. Frequency of CT scans is twice as high in Africa and Asia compared with eastern and central Europe, according to a two-year IAEA study in 40 developing countries. Exposure levels appropriate for adults are being used for children in some facilities, the study found.
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