Study reveals frequent pediatric rad exposure

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The average child will be exposed to seven procedures using ionizing radiation before the age of 18, while nearly half of children receive a procedure with radiation in any given year, according to a study of more than 350,000 children published Jan. 3 in the Archives of Pediatrics and Adolescent Medicine.

"To our knowledge, we report the first large, population-based study examining the use of diagnostic imaging procedures with low-dose ionizing radiation specifically in a pediatric population," wrote Adam L. Dorfman, MD, of the department of pediatrics at the University of Michigan Medical School in Ann Arbor, and co-authors.

Dorfman and colleagues investigated the occurrence of procedures using radiation in 355,088 children enrolled in UnitedHealthcare from 2005 through 2007. The sample included all such enrollees residing in Arizona; Dallas, Texas; Orlando, Florida; south Florida; and Wisconsin, and included plain radiography procedures, CT, fluoroscopy and/or angiography and nuclear medicine scans.

"Among 355,088 children across five large health care markets in the U.S., we found that use of these procedures during a three-year study period was frequent, with at least one of these procedures being performed in 42.5 percent of children. Importantly, many children underwent more than one procedure," the researchers reported.

A total of 436,711 procedures using ionizing radiation were reported over the three-year study. Plain x-rays comprised the most common procedures, with 40 percent of children receiving at least one procedure during the study. Twenty-two percent of children received two or more radiography procedures and 14 percent received three or more.

CT was the second most common procedure, with 8 percent of children receiving at least one over the study period. Two percent of children received one or more fluoroscopy and/or angiography procedures and 1 percent received a nuclear medicine scan. Radiography accounted for a total of 85 percent of all procedures.

"Based on these data, the average child in this study population will have received more than seven procedures by the time he or she reaches age 18 years," Dorfman and colleagues wrote. Overall, male enrollees had higher rates of imaging than females, with 44 percent of boys and 41 percent of girls receiving at least one procedure using radiation. Children over ten years of age also had significantly higher imaging rates.

The authors expressed concern given the National Research Council's findings that any exposure to radiation poses at least some risk, while also citing studies indicating that risk increases linearly with greater exposure to radiation. "Developing tissues in children are more sensitive to radiation and their longer expected life spans also allow additional time for the emergence of detrimental effects," said co-author, Reza Fazel, MD, of the department of cardiology at Emory University School of Medicine in Atlanta.

The authors made no attempts to judge the appropriateness of the procedures, however, while also abstaining from estimating radiation doses due to "a paucity of available data on radiation dosimetry in the pediatric population." They also cautioned that conducting the study in five states and considering only insured children might limit the generalizability of their findings.

"Of course, there is immense life-saving value in medical imaging, so our study doesn't suggest at all that these tests shouldn't be used in children," said co-author Kimberly E. Applegate, MD, vice chair for quality and safety in the department of radiology at Emory.

"It should encourage discussions about the value of each imaging test that is ordered, recognizing that radiation exposure, even in small amounts, may not be risk free," stated study co-author Andrew J. Einstein, MD, PhD, a cardiologist at Columbia University in New York City.