Measurement and analysis of gating latency in surface-guided particle therapy

Zhang Xiyu; Sheng-Yin Xiangzi; Shen Zhuangming; Yang Yuze

doi:10.11884/HPLPB202537.250229

Volume 37 Issue 10

Sep. 2025

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Zhang Xiyu, Sheng-Yin Xiangzi, Shen Zhuangming, et al. Measurement and analysis of gating latency in surface-guided particle therapy[J]. High Power Laser and Particle Beams, 2025, 37: 106024. doi: 10.11884/HPLPB202537.250229

Citation:

Zhang Xiyu, Sheng-Yin Xiangzi, Shen Zhuangming, et al. Measurement and analysis of gating latency in surface-guided particle therapy[J]. High Power Laser and Particle Beams, 2025, 37: 106024. doi: 10.11884/HPLPB202537.250229

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Measurement and analysis of gating latency in surface-guided particle therapy

doi: 10.11884/HPLPB202537.250229

Zhang Xiyu^{1, 3, 4
,},
Sheng-Yin Xiangzi^{2, 3, 4},
Shen Zhuangming^{1, 3, 4},
Yang Yuze^{1, 3, 4
,
,}

1.
Department of Medical Physics, Shanghai Proton and Heavy Ion Center, Shanghai 201315, China
2.
Department of Medical Physics, Shanghai Proton and Heavy Ion Center, Fudan University Cancer Hospital, Shanghai 201315, China
3.
Shanghai Key Laboratory of Radiation Oncology, Shanghai 201315, China
4.
Shanghai Engineering Research Center of Proton and Heavy Ion Radiation Therapy, Shanghai 201315, China

Received Date: 2025-07-20
Accepted Date: 2025-09-05
Rev Recd Date: 2025-09-03

Available Online: 2025-09-20

Publish Date: 2025-10-15

Abstract

Abstract

Background
Particle therapy is highly sensitive to respiratory motion, and low-latency respiratory gating is essential to ensure dose accuracy. Surface-guided radiation therapy (SGRT), featuring continuous monitoring and a non-ionizing workflow, is increasingly adopted in particle therapy and has become an important approach to respiratory gating. However, validation of gating latency for SGRT-guided proton and heavy ion systems remains limited in this area.
Purpose
To measure the gate-on and gate-off latencies of an SGRT-proton and heavy ion radiotherapy system using two different methods, compare the two experimental approaches, and evaluate the latency performance of the SGRT-guided system to inform its clinical application.
Methods
Two measurements were conducted using a PPL film method and a high-speed camera-detector method. In the film method, a proton beam traversed a 1.5-mm-diameter aperture in a lead collimator, producing on the film a striped pattern that encodes latency; the films were digitized at 0.10 mm resolution for analysis. In the camera-detector method, a 240 frames/s high-speed camera recorded the instant the gating condition was met, and gate-on and gate-off delays were computed from the time difference to the detector-registered radiation signal. End-to-end latency was measured with both methods, and results were cross-validated using combined uncertainty.
Results
The gate-on latency measured by the film method and the camera–detector method was 79 ms±10 ms and 67 ms±10 ms, respectively; the corresponding gate-off latency was 101 ms±9 ms and 129 ms±5 ms. Across two measurement methods, gate-on latencies were concordant within the combined standard uncertainty, whereas gate-off latency showed a significant method-dependent discrepancy, indicating systematic bias.
Conclusions
The SGRT-proton and heavy ion gating system meets our clinical requirements. This study demonstrates the feasibility and necessity of multi-method cross-validation of gating latency and provides quantitative evidence for the commissioning and acceptance test of SGRT in particle therapy.
- proton therapy,
- optical surface monitoring,
- respiratory gating,
- gating latency,
- multi-method validation

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References(16)

References

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