ESTRO 2025 - Abstract Book

S2768

Physics - Dose prediction, optimisation and applications of photon and electron planning

ESTRO 2025

Figure1 Box-and-Whisker plots showing differences in plan complexity between manual and automatic plans.

Conclusion: Automatic plans matched clinically accepted manual plans, with improved OAR sparing and comparable target coverage. Reduced plan complexity, and shorter planning times demonstrate the effectiveness of mCycle auto planning system, presenting it as a valid option in daily clinical practice for VMAT-TBI.

Keywords: Auto-planning, VMAT-TBI, MCO

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Digital Poster Prediction of primary ovarian insufficiency risk of pediatric whole-craniospinal irradiation in VMAT and IMPT Keisuke Usui 1,2 , Eiichi Maehara 1 , Hajime Sakamoto 1 , Shinsuke Kyogoku 1 1 Radiological Technology, Juntendo University, Tokyo, Japan. 2 Radiation Oncology, Juntendo University, Tokyo, Japan Purpose/Objective: Childhood cancer survival rates are ≤80%, but secondary cancers, growth disorders, and fertility preservation are greater concerns in children than in adults. Whole-craniospinal irradiation (CSI) is crucial for preventing leptomeningeal dissemination in pediatric medulloblastoma. However, to prevent ovarian insufficiency, ovarian doses must be ≤1.5 Gy, but they still pose infertility risks. Volumetric modulated arc therapy (VMAT) is widely used in CSI treatment planning and has good target-dose conformity. Intensity-modulated proton therapy (IMPT) with a single-field uniform dose is used in pediatric CSI to prevent lower dose spread due to the Bragg peak and low scattering. Predicting the risk of primary ovarian insufficiency before CSI irradiation would allow treatment plan optimization to protect the ovaries and help preserve fertility after treatment. This study aimed to develop a predictive model of the ovarian insufficiency risk from each irradiation technique at different ovarian doses for pediatric patients with CSI.