The Grapevine

Are CT Scans Safe? Childhood Exposure To Radiation May Increase Cancer Risk

Medical imaging exams, such as computed tomography (CT) scans, provide an image of structures inside our body. The technology can help detect and monitor numerous medical conditions and is less expensive and less invasive compared to surgery.

But, many worry about the possibility of adverse effects, namely the possible cancer risk elevation. In a new study, researchers from the Netherlands evaluated the risks of leukemia and brain tumor following childhood exposure to radiation from CT scans.

The paper titled "Radiation Exposure From Pediatric CT Scans and Subsequent Cancer Risk in the Netherlands" was published in the Journal of the National Cancer Institute.

The study examined data from 168,394 Dutch children who received one or more CT scans between 1979 and 2012. While they found no associations for leukemia, the risk of brain tumor was linked to the quantity of radiation in a dose to the brain. The press release stated relative risks increased to between two and four for the highest radiation doses.

Drawing conclusions from such studies remain a challenge according to lead researcher Michael Hauptmann from the Netherlands Cancer Institute.

For one, CT scans may be used to identify conditions associated with an increased tumor risk. So the major limitation is how the cohort of patients receiving scans may already have a higher incidence of brain tumors compared to the rest of the population.

"Nevertheless, our careful evaluation of the data and evidence from other studies indicate that CT-related radiation exposure increases brain tumor risk," Hauptmann said. "Careful justification of pediatric CT scans and dose optimization, as done in many hospitals, are essential to minimize risks."

Children are more radiosensitive than adults, according to the Food and Drug Administration (FDA). As a result, professionals are advised to use medical imaging techniques adjusted to administer the lowest possible radiation dose.

But despite the possible increase in cancer risk, the actual number of additional cases caused by radiation exposure is very small. Researchers behind similar studies have assured that the benefits of a CT scan ultimately outweigh the mild risks.

But the technology should only be used when absolutely necessary and clinically justifiable — a recommendation which is not always followed.

"People aren't focusing as much on clinical skills like taking a patient's history and doing a physical examination," explained Dr. Thomas Pranikoff, a pediatric surgeon from Brenner Children's Hospital in North Carolina.

In many cases, young patients only need to be observed in a safe setting. But parents may push for an unnecessary CT scan to receive a faster diagnosis. "They want an answer right away and that puts a lot of pressure on the doctors taking care of them," he said.

If a CT scan is offered, patients and parents are advised to speak to the doctor and understand the reason why. If needed, they can inquire about alternative approaches.