Although the risk is relatively small, many parents and doctors are raising such concerns. About 7 million of the scans are performed annually on children in the United States, a figure that has been rising 10 percent a year, according to the Alliance for Radiation Safety in Pediatric Imaging.
According to the National Cancer Institute, about a third who have undergone CT scans have had at least three. But sometimes, doctors said, scans are overused as parents push for an extra measure of assurance that a child is all right and as physicians try to guard against getting sued.
Many medical providers have pledged to reduce unnecessary CTs, with 15,798 signing on to an alliance campaign developed five years ago called Image Gently. That campaign promotes performing scans only when the medical benefit is clear. The alliance for radiation safety says one CT scan of a child’s head is equivalent to as much as eight months of naturally occurring background radiation from sources such as air and water. And an abdominal CT is equivalent to 20 months’ exposure. (Experts point out that background radiation is not directly comparable because it affects the whole body while the scans target only one part.)
By contrast, a chest X-ray exposes a child to the equivalent of one day of background radiation.