ESTRO 2025 - Abstract Book

S3115

Physics - Inter-fraction motion management and offline adaptive radiotherapy

ESTRO 2025

1804

Poster Discussion Sanity checks for rapid plan approval in online-adaptive proton therapy: Acceptance thresholds for plan parameter changes Lukas C Wolter 1,2 , Kenneth Poels 3 , Kevin Souris 4 , Kristin Stützer 1,2 , Christian Richter 1,2,5 1 High-precision proton therapy research group, OncoRay – National Center for Radiation Research in Oncology, Faculty of Medicine and University Hospital Carl Gustav Carus, Technische Universität Dresden, Helmholtz-Zentrum Dresden - Rossendorf, Dresden, Germany. 2 Institute of Radiooncology - OncoRay, Helmholtz-Zentrum Dresden - Rossendorf, Dresden, Germany. 3 Department of Radiotherapy Oncology, University Hospitals Leuven, Leuven, Belgium. 4 IBA, Ion Beam Applications SA, Louvain-la-Neuve, Belgium. 5 Department of Radiotherapy and Radiation Oncology, Faculty of Medicine and University Hospital Carl Gustav Carus, Technische Universität Dresden, Dresden, Germany Purpose/Objective: Online-adaptive proton therapy (OAPT) requires automated, phantom-less patient-specific quality-assurance (PSQA), as the patient remains in treatment position. In addition to prospective secondary dose calculation and retrospective log-file-based QA, sanity checks ensure the plausibility of adapted plan changes and data integrity before treatment. Some parameters must either match the nominal plan (hard-checks), or vary within specified tolerances (soft-checks). As these variations are case-specific, we developed and tested a soft-check threshold definition method based on two target entities and adaptation techniques.

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