ESTRO 2025 - Abstract Book

S3603

Physics - Quality assurance and auditing

ESTRO 2025

Conclusion: A simple procedure was established with the same phantom used for CT calibration. The large number of different inserts represents a wide variety of possible patient anatomies. The E2E test covers all important parts of the complete delivery chain and is performed periodically once every year in each room of WPE and as part of commissioning procedures. The agreement between the measured and calculated values from the TPS are well within defined tolerances.

Keywords: End-to-End-Test, Proton Therapy

References: [1] B. Arjomandy et al. , “AAPM task group 224: Comprehensive proton therapy machine quality assurance,” Med. Phys. , vol. 46, no. 8, Aug. 2019, doi: 10.1002/mp.13622. [2] DIN 6864-1:2020-10, Konstanzprüfung der strahlentherapeutischen Kette_- Teil_1: Teletherapie . doi: 10.31030/3185058. [3] Gammex Inc., User’s guide Advanced Electron Density Phantom Model 1467 . SunNuclear corporation, 2020. [4] International Atomic Energy Agency, Specification and Acceptance Testing of Radiotherapy Treatment Planning Systems . Vienna, Austria, 2007.

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Digital Poster Dose planning pre-trial quality assurance in the NIELS trial for patients with limited disease small cell lung cancer Sara Linde 1,2 , Ditte S Møller 1,2 , Mai-Britt Linaa 1 , Erik Almhagen 3,4 , Christina Larsen 5 , Nina Levin 6,7 , Mikkel D Lund 8 , Lars Merring-Mikkelsen 9 , Fernanda Villegas 3,4 , Tine B Nielsen 10 , Wiviann Ottosson 5 , Hella MB Sand 9 , Hjørdis H Schmidt 1 , Weronika M Szejniuk 11,12 , Lone Hoffmann 1,2 1 Department of Oncology, Aarhus University Hospital, Aarhus, Denmark. 2 Department of Clinical Medicine, Aarhus University, Aarhus, Denmark. 3 Department of Oncology-Pathology, Karolinska Institute, Stockholm, Sweden. 4 Medical Radiation Physics and Nuclear Medicine, Karolinska University Hospital, Stockholm, Sweden. 5 Department of Oncology & Radiotherapy Research Unit, Copenhagen University Hospital – Herlev and Gentofte, Herlev, Denmark. 6 Department of Clinical and Molecular Medicine, Norwegian University of Science and Technology, Trondheim, Norway. 7 Department of Oncology, St. Olavs Hospital, Trondheim, Norway. 8 Department of Oncology, Vejle Hospital, Vejle, Denmark. 9 Department of Oncology, Aalborg University Hospital, Aalborg, Denmark. 10 Department of Oncology, Odense University Hospital, Odense, Denmark. 11 Department of Oncology & Clinical Cancer Research Center, Aalborg University Hospital, Aalborg, Denmark. 12 Department of Clinical Medicine, Aalborg University, Aalborg, Denmark Purpose/Objective: Quality assurance (QA) in multicenter radiotherapy trials is highly important, but often neglected. It is crucial to secure viable outcome data, and to catch pitfalls before the trial onset. The NIELS trial, a Nordic phase III trial of inhomogeneous dose-escalated radiotherapy in small cell lung cancer (SCLC), with a primary aim to improve overall survival in patients with limited disease SCLC (LD-SCLC) is planned. Before the initiation of the protocol, pre-trial QA was performed. Here, we report the results. Material/Methods: In the trial, eligible patients with LD-SCLC will be randomized to either 60Gy in 40 fractions (fx) 10 fx per week, established by the THORA trial [1] or inhomogeneous dose-escalated radiotherapy aiming for mean doses to tumor (GTVt) and lymph nodes (GTVn) as high as possible up to 80Gy/40fx/10week without exceeding dose constraints to organs at risk (OAR). The trial design and an example of inhomogeneous dose-escalation are presented in Figure 1. Seven Nordic centers participated in the pre-trial QA study, consisting of a dose-planning dummy-run. All centers