S2371
Physics - Quality assurance and auditing
ESTRO 2026
Calusi 1 , Marta Casati 1 , Ilaria Cupparo 1 , Cinzia Talamonti 1,4 , Francesca Romana Giglioli 5 , Pietro Mancosu 6 , Serenella Russo 7 , Stefania Pallotta 1,4 1 Medical Physic Unit, Azienda Ospedaliera Universitaria Careggi, Florence, Italy. 2 Medical Physic Unit, Azienda USL Bologna, Bologna, Italy. 3 Radiotherapy Department, Azienda Ospedaliera Universitaria Careggi, Florence, Italy. 4 Experimental and Clinical Biomedical Sciences “Mario Serio”, University of Florence, Florence, Italy. 5 Medical Physic Unit, A.O.U. Città della Salute e della Scienza, Turin, Italy. 6 Medical Physic Unit, IRCCS Humanitas Research Hospital, Milan, Italy. 7 Medical Physic Unit, Azienda USL Toscana Centro, Florence, Italy Purpose/Objective: Technological advances in radiotherapy have greatly increased treatment complexity and patient throughput, requiring robust and efficient Quality Assurance (QA) programs to ensure safety and accuracy. In accordance with European directives, dosimetric verification should be performed for all treatment plans. However, high workloads, variability in detection tools/modalities, as well as the participation of different professionals, make this challenging. To address this, the Lean methodology was applied to optimize and standardize the pre- treatment Patient-Specific Quality Assurance (PSQA) process in a high volume Radiotherapy Department. Material/Methods: The project was conducted from October 2023 to February 2024 by a multidisciplinary team of medical physicists and radiation therapy technologists (RTTs), coordinated by a Green Belt Six Sigma facilitator and supported by the Italian Association of Medical Physics SBRT working group.Lean tools including Value Stream Mapping, Affinity Diagram, Ishikawa Diagram, Root Cause Analysis, 5-Why method, and A3 reporting - a structured one-page problem-solving approach used to summarize issues, analyses, and countermeasures- were applied to analyze and optimize the PSQA workflow. Four Elekta VHD linacs were included in the analysis, with ArcCHECK®, IQM®, and EPID (EPIbeam®) systems used for dosimetric verification. Key Performance Indicators (KPIs) and the flow index (the ratio between effective working time and the total process time) were defined to evaluate improvements in process efficiency, PSQA coverage, and team performance before and after Lean implementation. Results: Initial mapping revealed a flow index close to unity (1.18–1.20), suggesting a well-structured but potentially improvable process. KPIs considered are reported in Table1. Five procedures were revised or newly created, and all RTTs (30 in total) received standardized training, enabling autonomous PSQA delivery. QA coverage increased substantially: while
Conclusion: Phantoms with realistic skull anatomy achieved the closest sCT–rCT agreement, while hollow shells underperformed. Centers should prioritize MR- compatible phantoms with bone HU and skull complexity, documenting metrics within trigger-based QA. References: 1. Masitho, S., et al., Accuracy of MRI-CT registration in brain stereotactic radiotherapy: Impact of MRI acquisition setup and registration method. Z. Med. Phys., 2022. 32(4): p. 477-487.2. Villegas, F., et al., Challenges and opportunities in the development and clinical implementation of artificial intelligence based synthetic computed tomography for magnetic resonance only radiotherapy. Radiother. Oncol., 2024. 198: p. 110387.3. Claessens, M., et al., Quality Assurance for AI-Based Applications in Radiation Therapy. Semin. Radiat. Oncol., 2022. 32(4): p. 421- 431.4. Schmitt, D., et al., Technological quality requirements for stereotactic radiotherapy. Strahlenther. Onkol., 2020. 196(5): p. 421-443. Keywords: synthetic CT, Quality Assurance, Head phantom
Mini-Oral 2874
Applying Lean Methodology for Pre-Treatment Verification Process Optimization and Automation Margherita Zani 1 , Grazia Mistretta 2 , Chiara Arilli 1 , Pina Nuzzo 3 , Monica Morroni 3 , Livia Marrazzo 1,4 , SIlvia
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