Comparative Analysis of Effective Doses of Medical Exposure in Children on PET/CT with Digital and Analog Detectors

Abstract

Purpose: To assess the effective dose (ED) associated with 18F-FDG PET/CT in pediatric patients undergoing examinations on PET/CT scanners equipped with digital detectors, to quantify the contributions of the PET and CT components to the total dose, and to compare the findings with data obtained from previous-generation PET/CT systems. Materials and Methods: This single-center retrospective study included 1,899 pediatric patients who underwent 2,793 PET/CT examinations in 2024–2025 on two Discovery MI scanners (General Electric Healthcare, USA) with a 20-cm axial field of view. Patients were stratified into four age groups: 0–2, 3–7, 8–12, and 13–17 years. The ED attributable to the PET component was estimated from the administered 18F-FDG activity using age-specific dose coefficients in accordance with MU 2.6.1.3700-21, while the ED from the CT component was calculated from the dose-length product (DLP) using the corresponding age-specific conversion coefficients specified in MU 2.6.1.3584-19. Results:The mean total ED was 21.7 mSv (range, 7.1–82.8 mSv). With increasing age, the relative contribution of the CT component increased from 49.2% to 76.9%, whereas the contribution of the PET component decreased from 50.7 % to 23.0%. The strongest effect on total ED was associated with additional contrast-enhanced CT acquisitions, which increased total ED by 34–65%. Neither patient arm position nor scan length showed a consistent association with ED. Compared with previous-generation PET/CT systems, total ED was reduced by 4.7–10.1% across the age groups, primarily due to a 17–21% reduction in the PET component. Conclusion: The use of PET/CT systems equipped with digital detectors is associated with a reduction in radiation exposure in pediatric patients. Further dose optimization should focus primarily on the CT component, particularly the use of additional contrast-enhanced CT acquisitions.