As CT scans become more common for children, concerns about radiation grow

Isabel Doran is only 4 years old, but she's already had about 15 CT scans — and every one comes with a dose of radiation.

“I think there’s always that part of you that thinks it’s too much,” said her mother, Veronica Doran of Burke.

Doran is glad the scans have allowed doctors at Children’s National Medical Center to monitor Isabel’s progress while they treat her for a kidney cancer called Wilms’ tumor. But she’s worried about the long-term effects of the scans, which could put Isabel at risk for another cancer down the road.

Although the risk is relatively small, many parents and doctors are raising such concerns as the use of CT scanning has surged among the young. About 7 million of the scans are performed annually in 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, a consortium of medical organizations.

A study published online in April in the journal Radiology found that in almost 17 million emergency room visits by children from 1999 to 2007, the odds of a child's receiving a CT scan rose every year. Those findings bolster research published in the same journal last year, which found that the number of ER visits nationally in which children were given CT scans rose fivefold between 1995 and 2008 — from 330,000 annually to 1.65 million.

Many children get more than one scan. According to the National Cancer Institute, about a third who have undergone CT scans have had at least three.

“There have been significant increases. What we’ve seen in adults has been mirrored in kids,” said Donald Frush, chairman of the American College of Radiology’s pediatric radiology commission. “We do much more by CT.”

Frush and other doctors said there’s a good reason for that: The scans produce detailed images that can help them diagnose and monitor problems.

“CT is a very, very helpful tool,” Frush said. “It is lifesaving.”

But sometimes, doctors said, it is 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. “Defensive medicine is very prevalent and does drive what people do,” Frush said.

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. A recent study suggests the number of CTs performed in children may be starting to drop in some places.

“It is helping,” Frush said. “We honestly are doing things better. We’re questioning things more.”

‘You sort of go on faith’

CT, short for computed tomography, uses X-rays generated from a machine rotated around the body to create three-dimensional pictures. It’s used to investigate such problems as lymphoma, neuroblastoma, kidney tumors, congential heart malformations, head injuries and abdominal pain.

Images produced by the scans are more detailed than regular X-rays, and they’re better at revealing bone fractures than magnetic resonance imaging scans, which don’t use radiation and show more detail when looking at soft tissue. CTs are also relatively quick, typically requiring around 15 minutes, and patients don’t have to hold still for long periods, as they do with MRIs.

The big drawback of CT is the radiation. 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, and four bitewing dental X-rays expose a child to the equivalent of 0.6 of a day’s background radiation.

A study published this month in the Lancet, done by researchers at the National Cancer Institute and others, found that children and young adults scanned multiple times by CT have a small increased risk of leukemia and brain tumors in the 10 years after their first scan.

Doctors say radiation has a cumulative effect, meaning the more X-rays, the greater the risk. They also say it takes at least a decade for a cancer to develop from radiation exposure, although they don’t know what level of radiation could initiate a chain reaction leading to cancer.

Raymond Sze, chief of diagnostic imaging and radiology at Children's Hospital, said it's difficult to quantify the risk of getting cancer from a CT scan. The numbers vary widely and are controversial. The Image Gently campaign says for every 1,000 children undergoing a single abdominal CT scan, one cancer will develop because of the CT. But the campaign points out that one in five people will develop cancer sometime in their lives regardless of exposure to medical radiation.

Meanwhile, research on populations exposed to radiation have shown slight increases in cancer risk even at low levels of radiation, especially in children.

Sze said there are reasons children are at higher risk than adults. They have rapidly growing tissues that are more sensitive to radiation, he said, and they have longer to live than adults, giving them more time for cancer to develop. Some experts say the youngest children are the most sensitive to radiation, partly because their cells are dividing at such a high rate.

Still, Sze said, CT is often the best tool when diagnosing or monitoring a serious illness.

“If the benefit to the child is greater than the theoretical risk,” he said, “it is appropriate.”

Doran, a child psychiatry nurse at Children’s, said she is very familiar with the complexity of balancing risk and benefit. She said she trusts her doctors and has been happy with her daughter’s treatment. And she said she has always been comforted when the scans showed progress against her daughter’s cancer, which is now in remission.

“I don’t feel it’s been an overuse of CTs,” she said. “I guess you sort of go on faith that it’s the best course of action.”

But she said radiation remains a concern, and “there’s always that thought in the back of your mind.”

Joining the campaign

The Image Gently campaign is designed to alleviate those concerns and reduce radiation exposure. In addition to recommending that scans be performed only when the medical benefit is clear, it advocates scanning only the indicated part of the body, avoiding multiple scans, using alternatives such as MRIs when possible, and lowering the dose of radiation to the minimum required to get a good image.

“People need to ask: Is it necessary? Can you do another test, such as an MRI? Can you wait a couple of days?” Frush said.

Doctors said not every hospital or imaging center has the same level of expertise in performing CTs on children, who sometimes can get a higher level of radiation than needed.

While only individual medical providers make the Image Gently pledge, hospitals and other facilities accredited for pediatric CT by the American College of Radiology must show they follow the protocols backed by the campaign. Such facilities commit to imaging children with appropriate, child-size doses of radiation. According to the alliance, such hospitals in the Washington area include, among others, Children’s, MedStar Georgetown University, some Inova facilities in Virginia, Shady Grove Adventist Hospital, Sibley Memorial and Suburban (through a joint venture with a doctor group).

In early May, the Food and Drug Administration introduced a proposal aimed at reducing unnecessary radiation exposure for children. It recommends that manufacturers design new X-ray imaging devices, including CT scans, with instructions and protocols concerning use in children. Companies that can’t demonstrate that their devices are safe and effective for children would be asked to include a label cautioning against use in children.

The agency is seeking public comment on the proposal, and plans a workshop in July that will include manufacturers, device users and patient advocates.

The FDA is also collaborating with the radiation safety alliance and device manufacturers to come up with safety training materials for scanning children with existing equipment. And the agency has launched a Web site with information on the risks and benefits of imaging.

Doctors suggest that parents help keep their children safe by talking to their children’s doctors about CTs, being advocates for their children and asking if an imaging facility takes steps to reduce radiation in children. Doctors said parents also should be careful not to push for CT scans when another test, such as an MRI, regular X-ray or in some cases ultrasound might be just as good.

Frush reiterated that CTs are sometimes the best course of action, especially when a child’s condition is serious or difficult to diagnose. Sze agreed, and said that a growing number of doctors are becoming more skilled in knowing when and how to use CT on children.

A study published online in February in the journal Pediatrics looked at two pediatric emergency departments and found no overall increase in CT use between 2003 and 2010, and a decrease in certain areas of the body where non-radiation-based tests were available. This "may correlate with increased awareness of radiation risk in children," concluded the researchers.

As for Doran, she brought Isabel in for another CT scan in mid-May — the last one she’ll need for a while.

“I’m pretty happy about that,” she said. “I’m glad that we’re getting to the end of it.”

Ungar is a medical writer at the Courier-Journal in Louisville.

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