Study Estimates Children’s Potential Cancer Risk from CT Scans

Medical experts are once again advising that children undergo CT scans only when medically necessary and using the smallest radiation dose possible, following a new study. The study calculated how much use of computed tomography (CT) scans in children has increased over the past 2 decades.

During CT scans, patients are exposed to radiation, which previous research has linked to an increased risk of cancer. Even with the increase, the risk of developing cancer from a CT scan remains small. However, children are more susceptible than adults to the risks of cancer from the radiation in CT scans and have more years of life ahead of them for cancer to develop.

CT scans are performed on children for a number of reasons, such as to evaluate them after an injury, look for the cause of neurological disorders or pain, or look for infection. They deliver a dose of ionizing radiation that is larger than a plain X-ray, but that varies depending on the scan.

Calculating radiation exposure

The study was published early online June 10, 2013 in JAMA Pediatrics. Researchers looked at CT scans of the head, abdomen/pelvis, chest, and spine in children younger than age 15 from 1996 to 2010. They found the use of CT between 1996 and 2005 doubled for children younger than age 5 and tripled for children between ages 5 and 14. CT use remained stable between 2006 and 2007, then began to decline.

The researchers estimate that 4,870 future cancers could be caused by the approximately 4 million CT scans performed on children each year. The amount of radiation delivered through the scans varies considerably. The study’s authors calculate that reducing the amount of radiation in the highest 25% of children’s CT scans to the average dose may prevent hundreds of future cancers.

It’s important to note that the study did not look at how many cancers actually developed in children who had CT scans. The figures are just estimates of the number that could develop.

Response from radiologists

Concern about children’s radiation exposure from CT scans isn’t new. The US Food and Drug Administration (FDA) and the National Cancer Institute (NCI) have issued notifications over the past several years about the use of CT scans in children. The FDA stresses the importance of adjusting CT settings for the weight and size of the patient, especially for children and small adults, in order to use the lowest amount of radiation possible. The NCI also stresses the importance of using the lowest possible dose, and notes that improvements in CT equipment in the last decade have allowed for better images at lower doses.

In addition, several radiologists’ organizations have formed the Alliance for Radiation Safety in Pediatric Imaging. The group has launched an initiative to raise awareness of ways to lower radiation doses in scans of children. In a letter to parents on its website, the group advises parents to understand how any CT scan will potentially benefit their child and ask the doctor the following questions:

  • Are there other tests (such as MRI or ultrasound) or actions (such as watching the child for several hours) that could be safely substituted for the CT scan?
  • Will my child receive a “kid-sized” radiation dose?
  • Have the facility and radiology professionals done all they can to lower the radiation dose as much as possible while finding out what’s wrong with my child?

The American Cancer Society medical and editorial content team
Our team is made up of doctors and master's-prepared nurses with deep knowledge of cancer care as well as journalists, editors, and translators with extensive experience in medical writing.

The Use of Computed Tomography in Pediatrics and the Associated Radiation Exposure and Estimated Cancer Risk. Published early online June 10, 2013 in JAMA Pediatrics. First author: Diama L. Miglioretti, PhD, University of Washington, Seattle.

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