Determination of Radiographic Exposure Parameters Based on Chest Thickness for Mobile Chest Radiography in Pediatric Patients at Phetchabun Hospital

Abstract

This prospective analytical study aimed to determine the Exposure Index (EI), Deviation Index (DI), and Entrance Surface Air Kerma (ESAK), evaluate the appropriateness of EI, DI, and ESAK, investigate the relationships between chest thickness and radiographic exposure parameters, and develop predictive equations for kilovoltage peak (kVp) and milliampere-second (mAs) based on chest thickness in pediatric mobile chest radiography. A total of 106 pediatric inpatients aged 1–14 years who underwent mobile chest radiography at Phetchabun Hospital between June and September 2025 were enrolled. Chest thickness, kVp, mAs, EI, DI, and ESAK were collected and analyzed using descriptive statistics, Chi-square test, and simple linear regression. The mean EI, DI, and ESAK were 377.9 ± 249.0, −0.05 ± 3.2, and 0.08 ± 0.07 mGy, respectively. EI and DI were outside the recommended ranges in 56.6% and 60.4% of patients, respectively, whereas 62.3% of patients had ESAK values within the Thai National Diagnostic Reference
Levels. Chest thickness was significantly and positively associated with kVp, mAs, and ESAK (p < 0.001). The predictive equations were kVp = 54.378 + 1.016 × chest thickness (cm) and mAs = 0.455 + 0.117 × chest thickness (cm). These findings indicate that chest thickness is a useful predictor of radiographic exposure parameters and may be applied to develop an exposure chart for pediatric mobile chest radiography, thereby reducing variation in exposure parameter selection and promoting radiation dose optimization according to the ALARA principle.