ESTRO 2025 - Abstract Book

S4356

RTT - Treatment planning, OAR and target definitions

ESTRO 2025

French multi-center dataset (DSC)

BraTS (DSC)

French multi-center dataset HD95 (mm)

BraTS HD95 (mm)

Zone

Necrosis

0.75

0.79

5.4

5.4

Edema

0.74

0.84

8.8

5.7

Enhancing Tumor 3.9 Table 1: DSC and HD95 results for the autosegmentation algorithm ran on French multi-center dataset and BRATS test datasets across different tumor zones. Conclusion: The results demonstrate that the automatic contouring approach has a robust performance, especially in enhancing tumor regions, and supports potential integration into clinical workflows, facilitating consistent practices at the target volume delineation stage. These findings open new possibilities for disease follow-up and should offer insights into tumor progression. Further studies will focus on five-zone segmentation and post-operative cases, targeting surgical cavity and post-operative modifications to enhance precision in disease monitoring and treatment adaptation. Keywords: glioblastoma, auto-segmentation, tumor subregions References: 1. Ronneberger, O., Fischer, P., & Brox, T. (2015). U-Net: Convolutional Networks for Biomedical Image Segmentation. Medical Image Computing and Computer-Assisted Intervention (MICCAI), 234–241. 2. Baid, U., Ghodasara, S., Mohan, S., Bilello, M., Calabrese, E., Colak, E., ... Bakas, S. (2021). The RSNA-ASNR-MICCAI BraTS 2021 benchmark on brain tumor segmentation and radiogenomic classification. arXiv preprint arXiv:2107.02314. 0.83 0.88 3.4

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Digital Poster Hypofractionated whole pelvic VMAT for high risk prostate cancer: Are OAR dose constraints easily achievable? Zeineb Naimi, Amal Riahi, Meriem Skouri, Raouia Ben Amor, Awatef Hamdoun, Rihab Haddad, Ghada Bouguerra, Lotfi Kochbati Radiation Oncology Department, Abderrahmen Mami Hospital, Ariana, Tunisia

Purpose/Objective: This study aimed to evaluate the feasibility of achieving OAR dose constraints from the POP-RT trial in hypofractionated whole pelvic VMAT for high-risk prostate cancer.

Material/Methods: Forty-five high risk prostate cancer patients planned for whole pelvic hypofractionated radiotherapy were included in this study. Treatment plans were generated using simultaneous integrated boost-VMAT technique. The prescription dose of 68Gy/25fractions to the prostate+seminal vesicles and 50Gy/25fractions to pelvic lymph nodes. The POP-RT trial dose constraints were used for treatment plan optimization. Dose volume histograms were generated for OAR including bladder, rectum, femoral heads and bowel bag. A dosimetric review was performed to assess conformity to POP-RT Trial dose constraints and identify OARs at highest risk of constraint breach. Results: All treatment plans achieved optimal target volume coverage. Femoral heads dose constraint (V50Gy<5%) was respected for all plans. The V40Gy, V50Gy and V60Gy to the rectum were met in more than 95% of plans. The V65Gy and V70Gy to the rectum exceeded dose constraints for 5 out of 45 plans (11% of cases), at < 5%. Bladder dose