S1878
Physics - Dose prediction/calculation, optimisation and applications for photon and electron planning
ESTRO 2026
Conclusion: This study assesses an alternative approach to sCT EDM generation, supporting a simplified, accessible direct to unit MRIgRT workflow for CF prostate treatments. sCT tended to outperform bCT for SBRT, while bCT remained competitive for CF leading to treatment plans that have no clinically relevant differences with respect to the actual clinical workflow. Further investigations are ongoing to provide a direct to unit MRIgRT workflow for SBRT prostate treatments. The research leading to these results has received funding from AIRC under MFAG 2024 - ID.31024 project References: 1 Cusumano, Davide, et al. "A deep learning approach to generate synthetic CT in low field MR-guided adaptive radiotherapy for abdominal and pelvic cases." Radiotherapy and Oncology 153 (2020): 205- 212. https://doi.org/10.1016/j.radonc.2020.10.018 Keywords: Direct to unit, deformable registration, MRIgRT From online adaptive radiotherapy workflow for prostate cancer patients towards a robust plan approach Francesca Dusi, Fabio Busato, Alessandro Testolin, Davide Fiorentin, Francesca Tessari, Mattia Nicoletto, Isabella Alessi, Claudio Antonelli, Erick Maffi, Martina Ometto, Marco Ciro Schifano, Marco Fusella Radiation Oncology Dept, Abano Terme Hospital, Abano Terme, Italy Purpose/Objective: Interfraction anatomical variations represent a major challenge in prostate radiotherapy, mainly due to bladder and rectum filling differences. Online adaptive radiotherapy (oART) improves daily dose distribution but requires dedicated systems and substantial resources. This study investigated whether a robust plan could achieve comparable clinical target volume (CTV) coverage and organs-at-risk (OARs) sparing to a Proffered Paper 2158 daily oART approach, and whether the standard clinical plan provides adequate performance across fractions. Material/Methods: Ten prostate cancer patients treated with Halcyon HyperSight (60 Gy in 20 fractions) were analyzed. Daily Acuros-reconstructed CBCTs were rigidly co-registered to the planning CT and auto-contoured in LimbusAI with manual review. The planning target volume (PTV) was obtained from the CTV with 5 mm isotropic (3 mm posterior) margins.Three different approaches were evaluated for each patient:Clinical plan recalculated on all 20 CBCTs (P0);Adaptive reoptimized plans
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