ESTRO 2025 - Abstract Book

S3644

Physics - Quality assurance and auditing

ESTRO 2025

2692

Digital Poster Commissioning techniques and results of an automated machine quality assurance test suite Lana Critchfield 1 , Cory Knill 1 , Ellie Durussel 1 , William Donahue 2 , Seng Boh Lim 2 , John Demarco 3 , Justin Mikell 4 , Michael Barnes 5 , Jim Irrer 1 , Jean Moran 2 1 Radiation Oncology, University of Michigan, Ann Arbor, USA. 2 Department of Medical Physics, Memorial Sloan Kettering Cancer Center, New York City, USA. 3 Radiation Oncology, Cedars Sinai, Los Angeles, USA. 4 Radiation Oncology, Washington University, St. Louis, USA. 5 Radiation Oncology, Calvary Mater Newcastle, Waratah, Australia Purpose/Objective: EPIDs provide efficiency improvements for linear accelerator quality assurance (QA) but use is limited beyond patient-specific QA and outside of manufacturer supplied tools due to validation challenges. The Automated Quality Assurance Consortium (AQA), a multi-institutional initiative, streamlines automation and utilizes a data repository to advance knowledge from QA measurements. This study establishes a framework to assess the AQA test suite’s ability to detect errors, providing a model applicable to other EPID-based QA software. Material/Methods: Using a decommissioned linear accelerator, inaccuracies were intentionally introduced for fields in a standard test suite. Measurements were made with both the EPID and an IC Profiler (ICP). Performance results were evaluated for enhanced dynamic wedge (EDW), focal spot, beam symmetry, volumetric modulated arc therapy (VMAT) dose rate gantry speed (DR-GS) and MLC leaf speed. Different EDWs were delivered to assess the suite’s ability to detect wedge factors and changes in EDW selection. The beam was steered to introduce errors into the focal spot and beam symmetry results. Systematic errors were created in the MLC tests to offset leaf banks or alter the dose rate. Results: For EDW measurements, ICP wedge factors averaged -0.80% lower than EPID wedge factors (range: -1.75% to 0.05%). All EDWs angles were correctly identified by the AQA test suite. For focal spot measurements, the beam was steered ±1mm in both crossplane and inplane directions. Difference between AQA and IC profiler focal spot position for 6MV ranged from 0.43mm to -0.41mm (average -0.05mm) inplane and 0.53mm to -0.56mm (average 0.05mm) crossplane. 16MV differences ranged between 0.53mm to -0.41mm (average -0.04mm) inplane and 0.42mm to -0.28mm (average 0.03mm) crossplane.

Symmetry difference between ICP and EPID were between -0.87% to 1.53% for 6MV and -2.45% to 1.23% for 16MV. The largest difference occurred at the extremes of the steering process where the measured symmetry values