 Children getting computed tomography (CT) scans may be exposed to excess radiation that can increase their cancer risk later in life, according to a study published in the February issue of the American Journal of Roentgenology (AJR). But experts agree that the benefits of CT scans outweigh any risk from using them.
Lead researcher David J. Brenner, PhD, a Professor of Radiation Oncology at Columbia University in New York, says about 1.6 million children under the age of 15 are given CT scans to the head and abdomen every year in the United States, and an estimated 1,500 of them may eventually die from cancer caused by excess radiation.
"Children are more sensitive to radiation than adults because their cells are dividing more rapidly, and radiation has the potential to damage the DNA that controls that division," Brenner says, noting that cancer is a disease of uncontrolled cell growth.
CT Scans Save More Lives
However, Brenner emphasizes that CT scans save many times more lives every year. The scans are used to help diagnose cancer, appendicitis, pneumonia, kidney disease, and other potentially life-threatening diseases.
"We?re not talking about a situation where one?s child should not have a CT scan. We?re talking about trying to estimate what the long-term risks are, and the answer is they?re pretty small, but potentially they might be reduced even more by lowering the radiation exposure in childhood CT scans," Brenner says.
Other researchers publishing in the same issue of AJR say too many institutions do not adjust radiation dosage when scanning children, and that should change.
A team led by Lane F. Donnelly, MD, a Staff Radiologist at Children?s Hospital in Cincinnati, reviewed CT scans performed on all the pediatric patients referred in a recent eight-month period. The scans were done at the referring institutions.
"Our survey asked whether there were any adjustments being made when children were scanned, and the conclusion was there really weren?t ? that most kids at the typical places were being scanned with parameters suitable for adults," Donnelly says.
Adjust Radiation Levels for Kids
His team notes that radiologists can reduce CT radiation to an appropriate level for kids by adjusting the current and exposure time. This still gives them a clear picture for diagnosis. "In many instances, we are able to use five or six times less radiation compared to the adult dosage, and we got just as good a picture," Donnelly says.
Like Brenner, Donnelly emphasizes that CT scans provide far more value than harm from excess radiation. "Let?s say a child is unconscious after a car accident, and there are questionable findings on the physical exam of the abdomen and they?re trying to decide whether to go to surgery or not," he says. "A CT scan in that case can help the child avoid surgery, or help him be rushed to life-saving surgery instead of bleeding to death with an undiagnosed ruptured spleen."
He adds that CT is equally valuable in many other situations, such as diagnosing cancers and other serious diseases when other tools simply are not as accurate or able to provide as much information.
Minimize the Risk
"Our take is that the potential radiation risk from getting a CT scan is probably very minimal, but it?s not zero," Donnelly says. "We?re trying to minimize it even more, making it closer to zero. But if a parent were to refuse to let their child get an indicated CT because of the potential radiation dose, I think they would really be doing their child a disservice."
A radiation expert with the National Cancer Institute (NCI) says Brenner?s report is probably substantially correct and supports the idea of making adjustments so that children are exposed to less radiation. "I would agree with Brenner that the procedures are beneficial and the benefits outweigh the risks, but if you can have the same benefit for less risk, then by all means, do it," says Charles Land, PhD, a Senior Investigator at NCI?s radiation epidemiology branch. Brenner estimates childhood radiation exposure adds about one-third of 1% to risk of dying of cancer.
An American Cancer Society (ACS) expert says the AJR reports provide useful information that can be of benefit to patients and radiologists alike. "The relative risk of cancer from childhood CT scans really is fairly small, but these studies provide important information that radiologists and parents can use to make sure that children continue to receive the considerable benefits of CT scans while minimizing any potential risks," says Ralph Vogler, MD, Scientific Program Director of Extramural Grants for the ACS.
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