Reirradiation For Pediatric Central Nervous System Tumors: Lq Model Vs Real Clinical Practice: Comparison Of Dose To Critical Structures And Clinical Outcome

Introduction:The management of recurrent brain tumors in children poses significant challenges due to the balance between achieving therapeutic efficacy and minimizing treatment-related toxicities.This abstract aims to inform about the management of CNS reirradiation in a single institution through a comparison of LQ-based model approach and real clinical practice.Methodology: Forty patients received reirradiation for recurrent brain tumors from 2018 to 2023.Both treatments were carried out in a single institution.The median time between the two treatment courses was 21.9 months.Based on LQ-model and literature data about time-related nervous tissue recovery we developed a model for calculating possible constraints.We collected clinical outcomes and treatment plans data from 29 patients who received reirradiation and compared prescribed doses to critical structures with calculated doses for those patients.Results: Median follow-up was 13.7 months.Twenty-six patients had doses exceeding one or more critical structures compared to LQ-model calculations.Along with this, 15 patients had doses to the brainstem and spinal cord lower by more than 15% accompanying target under coverage in 6 patients.Eight patients had local recurrence, and 5 of them had target under coverage.Nine patients (31%) developed radiation necrosis in reirradiated areas.