S2381
Physics - Quality assurance and auditing
ESTRO 2026
the importance of protocol clarity and staff trainingFMEA identified regular audits and operator training as essential for protocol qualitySee Figure 1 (bar chart) for visual summary.
Development and validation of dataset using commercial TPS and radiochromic films for transit dosimetry with EPIDs. Il Nuovo Cimento C 2025, 10.1393/ncc/i2025-25234-7 Keywords: EPID, AI-based, PSQA
Digital Poster Highlight 3489 ROC-Guided Portal Dosimetry and FMEA-Driven
Workflow for Rapid, Robust PSQA in Hypofractionated Breast Radiotherapy
Anna Trezza 1 , Aniello Crocano 1 , Paolo Bagalà 1 , Aurelia Caccavari 1 , Alessandra Petrocchi 1 , Antonella Stravato 1 , Daniela Musio 2 , Danilo Aragno 1 1 Medical Physics, San Giovanni Addolorata, Roma, Rome, Italy. 2 Radiotherapy Department, San Giovanni Addolorata, Roma, Rome, Italy
Workflow innovationThe protocol now provides immediate passage for any plan with PD (2%/2 mm) above 98.8%. Cases below this are routed to Octavius QA and, if needed, undergo review or replanning (see Figure 2, flowchart). Audits and checklists ensure traceability and allow continuous adaptation as clinical data grows, delivering measurable PSQA acceleration and resource optimization.
Purpose/Objective: With hypofractionated breast radiotherapy—including
FAST-Forward and Accelerated Partial Breast Irradiation (APBI)—now standard, clinics face
increasing demand for rapid, standardized patient- specific quality assurance (PSQA). This study presents a Receiver Operating Characteristic (ROC)-calibrated portal dosimetry (PD) threshold integrated with Failure Mode and Effects Analysis (FMEA)-based mitigations, establishing an efficient quality assurance (QA) workflow ready for clinical adoption. Material/Methods: Forty-three breast Volumetric Modulated Arc Therapy/Intensity Modulated Radiotherapy (VMAT/IMRT) plans (6X/6FFF) underwent quality assurance (QA) with both portal dosimetry (PD) and Octavius 4D. Gamma passing rate medians (first–third quartile) were evaluated for all clinical criteria (1%/1 mm to 4%/4 mm) using regions of interest (ROI); for 3%/3 mm and 2%/2 mm, Octavius was also analyzed without ROI for direct comparability with PD and receiver operating characteristic (ROC) analysis (threshold: Octavius ≥ 93%). FMEA was performed to identify process vulnerabilities and guide mitigation strategies, including scheduled audits and operator
Conclusion: Take-home message:Integrating ROC-calibrated PD triage and FMEA-guided process control accelerates PSQA and maximizes resource efficiency in modern hypofractionated breast radiotherapy.ConclusionsCombining a ROC-calibrated PD threshold with FMEA-driven process mitigations streamlines PSQA, optimizes resource allocation, and ensures robust control for critical or ambiguous cases—establishing an efficient, adaptable model for hypofractionated breast radiotherapy. References: McCurdy BM, Greer PB, et al. "AAPM Task Group 307 Report: Use of EPIDs for Patient-Specific IMRT and VMAT QA." Medical Physics. 2023. doi:10.1002/mp.16536.Klein EE, et al. "AAPM Task Group 218: Tolerance Limits and Methodologies for IMRT Measurement-Based Verification QA." Med Phys. 2018;45(12):e434-e459. doi:10.1002/mp.13034 Keywords: Portal Dosimetry,ROC analysis,Workflow optmization
training. Results:
Gamma passing rates are reported as median (first– third quartile):At 3%/3 mm, passing rates were:PD 99.9% (99.5%–100%)Octavius ROI 99% (97.8%– 99.4%)Octavius no ROI 97.8% (94.7%–99.3%)ROC analysis set PD > 98.8% (2%/2 mm) as the optimal triage threshold (specificity 100%, sensitivity 61.5%, AUC 0.686)Applying this cutoff, 25/43 plans were approved by PD alone; 18/43 required Octavius QA— higher-resource measurements reduced by ~60%, median QA time cut from 21 to 5 minutesPassing rates were strongly impacted by ROI inclusion, highlighting
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