ESTRO 2025 - Abstract Book

S4095

RTT - Patient care, preparation, immobilisation and IGRT verification protocols

ESTRO 2025

2712

Digital Poster Assessing setup errors and treatment duration in pediatric brain tumor patients: an analysis of age-related variability Andrea Lastrucci 1,2 , Neda Haghighatjou 1,2 , Alessia Pesci 3 , Daniela Greto 2 , Isacco Desideri 4,2 , Nicola Iosca 1,2 , Yannick Wandael 1 , Renzo Ricci 1 , Lorenzo Livi 4 1 Department of Allied Health Professions, Azienda Ospedaliero-Universitaria Careggi, Florence, Italy. 2 Radiation Oncology Unit, Azienda Ospedaliero-Universitaria Careggi, Florence, Italy. 3 University of Florence, University of Florence, Florence, Italy. 4 Department of Experimental and Clinical Biomedical Sciences "M. Serio", University of Florence, Florence, Italy Purpose/Objective: The treatment of pediatric patients introduces additional complexity to positioning, requiring the use of anesthesia in younger children to ensure immobility, along with the daily acquisition of Cone Beam Computed Tomography (CBCT) scans, performed to verify accuracy prior to treatment. This single-center retrospective study analyzed setup errors and treatment durations in pediatric brain tumor patients, focusing on age-related variability. Material/Methods: Setup errors were calculated by evaluating daily shifts, comparing CBCT images with CT simulation scans for all pediatric patients (aged ≤ 21 years) treated between 2021 and 2024. Participants were stratified into three distinct age groups: children under 5 years requiring anesthesia, children aged 6 to 12 years, and adolescents aged 13 to 21 years. Errors were assessed using 3D vector displacement to quantify isocenter shifts. Additionally, treatment durations and CBCT matching times were recorded and analyzed for each age group. Results: A total of 27 patients were included in this study, with adolescents comprising the largest cohort (n = 13, 48.1%). A comprehensive analysis of 688 CBCT scans was conducted to assess 3D vector displacements. Results showed that nearly half of the cases among adolescents (n = 168, 49.7%) exhibited a 3D vector displacement of less than 3 mm. In the youngest category (0–5 years, treated under anesthesia), the highest frequency of 3D vector displacement (n = 137, 72%) was below 5 mm. In contrast, the group aged 6–12 years displayed greater variability, with 40% of cases (n = 64) exceeding 5 mm, suggesting a higher incidence of significant setup errors within this age range. Treatment and matching CBCT time were comparable across age groups, averaging 8 ± 4 minutes and 4 ± 2 minutes, respectively.

Fugure 1. Histogram of the magnitude of the required 3D vector displacement based on the matching CBCT after patient positioning