Just under half of parents in a recent survey understood that radiation from a computed tomography (CT) scan is tied to an increased risk of cancer for their child.
There has been a growing understanding among the medical community in the past decade that children who have had a CT scan are slightly more likely to develop cancer later in life, researchers said.
One recent study found that for every 10,000 children under age 10 that have a scan, one additional child will develop cancer in the next decade.
Parents seem to be becoming more informed about that risk as well, according to Dr. Kathy Boutis, the lead author of the study.
"This number we found is actually much higher than previously reported," said Boutis, a pediatric emergency medicine physician and a senior associate scientist at the Hospital for Sick Children in Toronto.
Physician groups have responded to the potential hazard of CT scans - along with concern about their overuse - with efforts such as Image Gently, a campaign that aims to reduce the radiation dose for children and educate parents and doctors about the risks and benefits of imaging tests.
And some change seems to have resulted: after years of increases in CT scans for children, recently there has been a scaling back.
To see how well parents understand the risks of CT, Boutis and her colleagues surveyed 742 parents of children who came to the emergency room with a head injury.
CT scans are performed on some children with head trauma to make sure they don't have a significant brain injury.
About 47 percent of parents correctly believed that undergoing a CT scan is tied to a greater cancer risk over a child's lifetime, according to findings published in Pediatrics.
"We're finding that parents are aware of the risks more and more, both from what they're hearing in the media and what their clinicians are telling them," Dr. David Larson, an associate professor of pediatric radiology at Stanford University who wasn't involved in the study, said.
KNOWLEDGE AFFECTS DECISION-MAKING
At the start of the survey, 90 percent of parents said they would be "very willing" or "willing" to go ahead with a CT test if the doctor thought it was necessary.
But by the end of the questionnaire - after parents were informed about cancer risks - that number dropped to 70 percent. About six percent of the parents said they would outright refuse the test.
Dr. Marilyn Goske, chair for the Alliance for Radiation Safety in Pediatric Imaging, which runs Image Gently, said informing parents about the risks of CT scans is important, even if it makes them less eager to agree to the test.
Boutis's study found that 90 percent of parents wanted to be made aware of the risks.
Goske, who is also a radiologist at Cincinnati Children's Hospital Medical Center and wasn't involved in the new research, added that it's important to note that the survey was given to parents before they were faced with a decision about having their child imaged.
Of the 42 parents who said they would refuse a test, eight had children for whom a CT scan was later recommended - and all of those kids went ahead with the scan.
Boutis said doctors should inform parents about the risks of CT.
Dr. Benjamin Taragin, director of pediatric radiology at The Children's Hospital at Montefiore in Bronx, New York, who also wasn't part of the study team, said involving parents in the discussion can perhaps steer the conversation to alternative options, such as ultrasound or even watchful waiting, if possible.
However, there are times when the information gathered from a CT scan is necessary to treat the child, and the benefits far outweigh the small risk of cancer, he said.