ESTRO 2025 - Abstract Book

S3624

Physics - Quality assurance and auditing

ESTRO 2025

Figure 2-FourL analysis with two MLC models

Conclusion: This enhanced gamma index algorithm overcomes key limitations of the traditional metric by integrating signed data analysis and advanced visualization. These innovations enable more detailed and clinically relevant assessments of dose discrepancies, improving radiotherapy QA and machine modeling accuracy.

Keywords: Gamma index, Dose analysis, Quality Assurance

1785

Mini-Oral Phantom-based vs. phantom-less patient-specific QA in proton therapy: A comprehensive error detection sensitivity analysis Lukas C Wolter 1,2 , Yazeed Ghannam 1 , Stefan Menkel 3 , Kristin Stützer 1,2 , Christian Richter 1,2,3 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 and Radiation Oncology, Faculty of Medicine and University Hospital Carl Gustav Carus, Technische Universität Dresden, Dresden, Germany Purpose/Objective: Phantom-based patient-specific quality assurance (PB-PSQA) in proton therapy (PT) is resource-intensive, requiring additional beam time and personnel. We compared the error detection sensitivity of this standard PSQA workflow with a prototype phantom-less alternative (PL-PSQA) based on the increasingly recognized log-file-based approach. Both methods were applied to manipulated treatment plans and evaluated with clinical PSQA criteria to determine whether PL-PSQA could reliably replace the standard approach.