ESTRO 2025 - Abstract Book

S3665

Physics - Quality assurance and auditing

ESTRO 2025

All plans were measured using the MatriXX Resolution (IBA Dosimetry GmbH). Dose measurements and calculations were compared using a 2D γ-evaluation in myQA Patients (v. 2023-001, IBA Dosimetry GmbH) using criteria of 3% global dose and 2mm. Results: The measurements of all 13 reference plans passed the γ-evaluation with a pass rate >99%. The additional 6 adaptive plans also passed the γ-evaluation with a pass rate >99%. The four box plots in figure 1 show the complexity metric values of the reference plans and in addition, as red points, the values of the 6 measured adapted plans that fell outside the initial range of commissioned space.

Conclusion: For oART in breast cancer patients, a commissioned space was defined based on measurements of reference plans and subsequently expanded by additional plan measurements of adaptive plans. This strategy resulted in a reduction of required plan specific QA measurements. This strategy has been implemented for online-adaptive breast cancer plans and could be extended to any tumor site or even be generic for a whole machine type such as the Ethos system.

Keywords: Deliverability, Breast

References: 1 Kairn, T. et al., Predicting the likelihood of QA failure using treatment plan accuracy metrics. J. Phys.: Conf. Ser 2014 . 489 012051 2 Crowe S.B. et al., Treatment plan complexity metrics for predicting IMRT pre-treatment quality assurance results. Australas Phys Eng Sci Med 2014. 37, 475–482 3 Younge, K. C. et al., Penalization of aperture complexity in inversely planned volumetric modulated arc therapy. Medical Physics, 2012. 39 (11), 7160–7170