ESTRO 2025 - Abstract Book

S3705

Physics - Quality assurance and auditing

ESTRO 2025

Results: As shown in the time series plot in Fig. 1 the EMQA output, QA3 and Farmer chamber measurements qualitatively agree with each other. All disagreements between EMQA and Farmer chamber output drift were <1%.

Fig. 1: Time series plot of EMQA, QA3 and Farmer output drift from the start of the trial period for one linac.

In Fig. 2 we show a Bland-Altman plot comparing the output drift of EMQA and the QA3. No scale difference in the two measures is seen and nor is any evidence for outliers.

Fig. 2: A Bland-Altman plot comparing the EMQA and QA3 output drifts for one linac shown alongside 1.96σ confidence intervals (orange) and the average (green) differences.

Conclusion: MIQC tools such as EMQA provide new tools for performing linac QA. This study has shown the performance of the EMQA output test meets the need for daily output consistency QA.