ESTRO 2025 - Abstract Book

S3686

Physics - Quality assurance and auditing

ESTRO 2025

Results: The median end-to-end beam-on latency was 901 (IQR 868-934) ms (day 1) and 1652 (IQR 1576-1727) ms (day 2). The LED delay was 115 (IQR 83-157) ms and 135 (IQR 105-179) ms. Variations in beam ramp-up were attributed to the exchange of technical components, such as magnetron and gun. The end-to-end beam-off latency was 142 (IQR 121-159) ms (day1) and 134 (IQR 109-150) ms (day 2) while the LED delay was 141 (IQR 114-160) ms and 134 (IQR 106-175) ms.

Conclusion: This study quantifies ETD’s latencies for the first time. Due to signal transduction, the LED signal also reflects linac feedback, providing only an upper limit for ETD’s latencies. Future work will refine this method. The approach can be adapted for other SGRT systems installed with the Elekta “Response control module”.

Keywords: surface-guided radiation therapy, gating latencies

References: [1] Worm, E. S. et al. (2023). Medical Physics , 50 (6), 3289–3298.