Report from NCRP: Pediatric CT must balance quality, safety

April 19, 2007

Adherence to simple, systematic clinical guidelines is key to protecting children adequately against excessive or inappropriate exposure to ionizing radiation when they undergo diagnostic CT, according to a leading critic of CT practices in pediatric radiology.

Adherence to simple, systematic clinical guidelines is key to protecting children adequately against excessive or inappropriate exposure to ionizing radiation when they undergo diagnostic CT, according to a leading critic of CT practices in pediatric radiology.

Speaking at the 2007 National Council on Radiation Protection and Measurements meeting Monday, Dr. Donald P. Frush urged radiologists to use modalities that do not involve ionizing radiation, when possible, for imaging children and infants. Frush, director of pediatric radiology at Duke University Medical Center, has been a leader in efforts to better understand and manage CT imaging practices in pediatric radiology for nearly a decade.

"I consider the radiologists' responsibility with radiation the same as that physicians have with medications," he said.

Frush expressed concern about recent increases in the use of CT and the implications of the trend for infants, children, and adolescents. Of the more than 60 million CT exams performed in 2006, about seven million were performed on children, he said.

The growth rate is faster than can be justified by the known rates of disease and injury among infants and children, Frush said. Multislice CT is quickly replacing ultrasound, for instance, for some pediatric conditions. This practice may be driven by marketing, economics, or public opinion, but it flies in the face of known hazards, including long-term cancer risks associated with ionizing radiation exposure.

Dose and quality guidelines must be in place, taking into consideration individual parameters, Frush said.

The problem may be most severe in routine community-based clinical practices where most pediatric imaging is performed. Radiologists who work outside an academic environment may have difficulty determining the dose from MSCT. Frush and colleagues ran a pediatric phantom study with a 64-slice CT scanner just to find out what type of effective dose they could apply using different protocols. They found they could give an effective dose of up to 120 mSv.

"Our current ways of measuring CT dose are limited," Frush said. "This balance between safety and image quality comes through an understanding of MSCT dose, why we do CT, and how we do it."

Frush learned from the January 2006 Sago Mine disaster that killed 14 miners in West Virginia. Problems can be solved by improving communications, developing better response strategies, and avoiding the denial of responsibility and fingerpointing that punctuated that disaster.

He also discussed safety lessons that radiologists can learn from the U.S. military. He summed up the conclusions of a study outlining the steps taken by Naval Aviation to reduce fatal air mishaps in the Navy from 776 in 1954 to fewer than 40 by 1997. Strategies responsible for this improvement included reducing the reliance on human memory, using checklists, simplifying and standardizing procedures, promoting effective team functioning and communication, and monitoring safety progress.

A streamlined, standardized process has to define with certainty the imaging question that needs to be answered in pediatric cases, he said. It should take into account the technical limitations posed by a pediatric patient, such as body habitus. And it should help competent radiologists to follow these criteria.

The result is an exam that is both safe and of diagnostic quality, Frush said. A low-dose CT exam to obtain the volume of a child's liver, for example, may produce an image of poor quality from the point of view of noise, but one that can still answer the specific clinical question.

New CT scanning techniques are relatively unfamiliar for many radiologists, who need to take into account different radiation dose variables for children compared with those applied in adults. U.S. radiation law does not specifically regulate pediatric CT practices, but discussions are under way concerning the need for standardized pediatric doses and imaging quality guidelines, Frush said.

Special section: Exclusive coverage of the 2007 National Council on Radiation Protection and Measurements meeting

This year's historic NCRP meeting reveals the disturbing growth of patient exposure to ionizing radiation from medical imaging and proposes practical solutions to regulate its growth. Extended coverage from Diagnostic Imaging lays out the facts and recommendations to better protect patients, physicians, and medical staff.

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