Cone Beam Computed Tomography and Computed Tomography Doses Assessment in Pediatric Phantoms

Bruno Gonçalo Jesus Marques de Oliveira

Key information

Authors:

Bruno Gonçalo Jesus Marques de Oliveira (Bruno Gonçalo Jesus Marques de Oliveira)

Supervisors:

Ana Maria Morais Cravo de Sá; Salvatore di Maria (Salvatore di Maria)

Published in

December 22, 2025

Abstract

Introduction: Cone Beam Computed Tomography (CBCT) doses are typically two to three orders of magnitude lower than those delivered during conventional radiotherapy. Computed Tomography (CT) doses are higher per fraction, however, when performed daily, the cumulative CBCT dose can exceed that of a single CT. Assessing imaging doses is crucial in pediatric radiotherapy, as children are more radiosensitive due to their smaller size, developing tissues, and longer life expectancy. Methodology: CBCT and CT dose values were compared in this study to estimate total imaging doses in pediatric radiotherapy. A Metal–Oxide–Semiconductor Field-Effect Transistor (MOSFET) and a RaysafeXi ionization chamber were used to measure the absorbed organs doses under pediatric imaging procedures. Results: In general, doses measured with MOSFET were higher in CT compared to CBCT, with the differences reaching 2,65 mGy in the brain. CBCT doses ranged from approximately 0,09 mGy (lung) to 0,46 mGy (Cranium) while CT doses ranged from about 0,09 mGy (lung) and 3,10 mGy (brain). Conclusions: Cumulative doses, such as those in the brain (12,6–14,85 mGy), underscore the importance of evaluating the biological implications of repeated low-dose imaging in pediatric patients. Although these doses are low compared to therapeutic levels, they contribute to lifetime exposure and may increase the risk of stochastic effects. Continuous assessment and optimization of CBCT and CT protocols are therefore essential to ensure diagnostic quality while minimizing unnecessary radiation. Future work should include image quality analysis to determine the optimal balance between dose and performance for each technique.