Pediatric chest radiography in Fukushima prefecture: a multicentre organ dose assessment and optimization analysis.

Abstract

Pediatric patients are highly radiosensitive, and technical variation in chest radiography can substantially affect dose. Fukushima prefecture also faces persistent post-disaster radiation concerns and declining pediatric imaging experience due to demographic change. A 5 year-old anthropomorphic phantom with 50 radiophotoluminescent dosimeters was examined at 22 facilities. Organ absorbed doses and entrance surface air kerma (ESAK) were directly measured, and effective dose was calculated using International Commission on Radiological Protection Publication 103 tissue weighting factors. One statistical outlier identified by Tukey's extreme outlier criterion was excluded from outlier-excluded analyses. Across 22 facilities, ESAK ranged from 0.03 to 1.25 mGy (median 0.12 mGy) and effective dose from 3.4 to 180.1μSv (median 27.3μSv). After exclusion of one outlier, ESAK ranged from 0.03 to 0.26 mGy (median 0.12 mGy; 9-fold variation) and effective dose from 3.4 to 94.2μSv (median 27.2μSv; 28-fold variation). The 75th-percentile ESAK was 0.137 mGy, 2.5% below Japan diagnostic reference levels 2025 (0.14 mGy), although 5 of 21 facilities (23.8%) exceeded this level. Median effective dose was 1.4-fold higher than the international reference value (20μSv). Compared with posterior-anterior (PA) projection, anterior-posterior projection showed higher breast dose (151.8 ± 74.3 vs 18.6 ± 10.7μGy;p= 0.0011) and higher effective dose (55.9 ± 29.6 vs 21.7 ± 11.5μSv;p= 0.0059); the stomach dose difference was exploratory (p= 0.025), whereas the thyroid dose difference was not statistically significant (p= 0.050). Tube current-time product correlated positively with effective dose (r= 0.67,p< 0.001). Marked inter-facility variation indicates substantial opportunities for optimization through greater use of PA projection, appropriate source-to-image receptor distance extension, and careful mAs adjustment. In post-disaster regions with declining pediatric imaging experience, radiation protection may require integrated technical, educational, and societal support.