JACR: Mounting evidenceradiation dose to kids varies

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The vast majority of trauma centers utilize pediatric-specific CT radiation dose protocols, and yet, the effective doses administered for head CTs in Washington state varied by a factor of as much as ten within and between different trauma center levels, according to a study published in the April issue of the Journal of the American College of Radiology.

Trauma is the leading cause of morbidity and mortality among children over the age of one. Despite the existence of pediatric-specific radiation dose protocols among the more radiosensitive age group, little is known about the actual implementation of these standards.

“The purpose of this study was to examine variation in head CT protocols for injured children in Washington state to justify the need for protocol standardization to reduce radiation exposure in children,” stated Kalpana M. Kanal, PhD, and co-authors from the University of Washington in Seattle.

Seventy-six percent of Washington’s 77 trauma hospitals responded to the nine-question survey. All 10 of Washington’s levels 1 and 2 trauma centers returned the survey.

Higher-level trauma centers performed significantly more head CTs than lower-level hospitals. In 2007, level 1 centers performed an average of 696 pediatric head CTs, level 2 centers an average of 67, level 3 facilities an average of 27 and level 4 and 5 trauma centers performed 35 and 2, respectively.

All level 1 and 2 trauma centers reported having pediatric-specific dose protocols, while the proportions dropped to 88 percent for level 3 centers, 91 percent for level 4 and 71 percent for level 5.

Among level 4 trauma centers, effective dose varied tenfold, with a median dose of 3.5 mSv and a range of 0.60 to 9.60 mSv. Level 2 centers had the lowest doses (1.2 and 1.6 mSv). The average effective dose for an adult head CT is 2 mSv.

Tube voltage varied by only 20 kV, between 100 and 120 kV, with no significant differences observed between trauma center levels. Kanal and colleagues found a moderate correlation between higher amplitude (mAs) and lower trauma center level.

Among level 4 trauma centers, median dose to the brain was 37 mGy, ranging between 7.0 and 123.8 mGy, while the estimated dose to the eye lens was 42.4 mGy. Although this median lens dose fell shy of the 50- to 200-mGy dose that is known to cause visual opacities, some trauma centers did fall into this range. Median dose to the thyroid was 6.6 mGy.

The authors did not acquire sufficient data to compare radiation doses between adult- and pediatric-designated trauma centers. Kanal and colleagues did estimate the potential for significant dose savings—65 percent—at level 4 trauma centers if they were to adopt the protocols used at level 2 centers, which had the lowest effective doses.

“The main finding of this study is that there is variation both within and between TC [trauma center] levels in pediatric head CT imaging protocols and radiation dose in Washington state,” Kanal and co-authors noted.

“In this study, most responding TCs across Washington state used pediatric-specific protocols, suggesting a high level of awareness of the necessity of tailoring CT protocols for pediatric head imaging. We also observed that pediatric-designated centers were more dose conscious and used statistically significant lower mAs compared with adult-designated centers.”

Kanal and colleagues pointed out that Washington state has not legislated any CT quality or dose regulations; moreover, only 13 percent of the state’s trauma centers have achieved American College of Radiology (ACR) accreditation for pediatric CT. “Awareness of variation and associated risks is needed to reduce radiation exposure,” the authors concluded.

To learn more about the pediatric dose reduction, visit Image Gently.