ESTRO 2025 - Abstract Book

S3111

Physics - Inter-fraction motion management and offline adaptive radiotherapy

ESTRO 2025

Conclusion: The feasibility of the designed offline ART workflow was confirmed, with an overall treatment time comparable to those achieved with online ART-dedicated LINACs for LARC patients. Further investigation could explore the possibility offered by Polyquant of directly reconstructing in RED, overcoming the pop-CC calibration. Also, it may be possible to evaluate the benefits of offline ART for LARC patients and investigate its application for other prescription and districts. Moreover, dose accumulation should be validated to offer an additional evaluation tool during treatment delivery.

Keywords: CBCT, auto contouring, scripting

1742

Digital Poster Clinical Potential of Offline Adaptive Radiotherapy Using Halcyon-HyperSight CBCT for Breast Cancer Patients: Image quality and dosimetric evaluation Hae-Jin Park 1 , Jina Kim 2 , Mi-Hwa Kim 2 , O Kyu Noh 2 , Young-Taek Oh 2 1 Department of Radiation Oncology, Ajou University School of Medicine, Suwon, Korea, Republic of. 2 Radiation Oncology, Ajou University School of Medicine, Suwon, Korea, Republic of Purpose/Objective: To evaluate the significance of adaptive radiotherapy using HyperSight Cone Beam Computed Tomography (CBCT) imaging for breast cancer patients experiencing tumor volume and position changes during treatment, compared to conventional planning CT and Halcyon CBCT. Material/Methods: Ten breast cancer patients undergoing cross-treatment with Halcyon v3.1 and Halcyon-HyperSight v4.0 systems due to anatomical changes were selected. Images were acquired at 125kV with 2mm slice thickness. HyperSight used iCBCT_Acuros algorithm, while Halcyon CBCT used Feldkamp–Davis–Kress (FDK) algorithm. Image quality was