Although most will have x-rays, some will also be exposed to CT scans, which emit much higher levels of radiation, and which could lead to health problems such as cancer, say researchers from the University of Michigan.
They made the discovery when they analysed the health records of 355,088 children under the age of 18 from five areas of the US. Overall, 42 per cent of the children had undergone at least one medical screening over the previous three years, and 400,000 procedures had been performed.
Around 8 per cent of the children had received a CT scan, and nearly half of these had been given more than one.
(Source: Archives of Pediatrics and Adolescent Medicine, 2011; doi: 10.1001/archpediatrics.2010.270).