光学体表引导粒子放疗门控延迟的测量与分析

章希煜; 盛尹祥子; 沈庄明; 杨昱泽

doi:10.11884/HPLPB202537.250229

光学体表引导粒子放疗门控延迟的测量与分析

doi: 10.11884/HPLPB202537.250229

章希煜^{1, 3, 4,},
盛尹祥子^{2, 3, 4},
沈庄明^{1, 3, 4},
杨昱泽^{1, 3, 4, ,}

1.
上海市质子重离子医院放射物理科，上海 201315
2.
上海市质子重离子医院，复旦大学附属肿瘤医院放射物理科，上海 201315
3.
上海市放射肿瘤学重点实验室，上海 201315
4.
上海质子重离子放射治疗工程技术研究中心，上海 201315

基金项目: 上海市浦江人才计划（23PJ1411100）；上海市卫生健康委员会（2024ZZ2054）；国家科技重大专项课题（2024ZD0519901）；“SPHIC新锐”人才培养计划（SPHICXR202302）

详细信息

作者简介:
章希煜，xiyu.zhang@sphic.org.cn

通讯作者:
杨昱泽，yuze.yang@sphic.org.cn。

中图分类号: R815.6
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- 文章访问数: 92
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- 被引次数: 0
出版历程
- 收稿日期: 2025-07-20
- 修回日期: 2025-09-03
- 录用日期: 2025-09-05
- 网络出版日期: 2025-09-20
- 刊出日期: 2025-10-15

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

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

摘要

摘要: 粒子放疗对呼吸运动高度敏感，低延迟的呼吸门控是确保剂量准确的重要前提。光学体表引导（SGRT）因其具备连续监测与无电离辐射的特性，在粒子放疗中的应用日益增多，成为了呼吸门控的重要手段。然而，放疗领域对于SGRT-质子重离子门控系统时间延迟的验证仍然有限。采用两种不同方法测量SGRT-质子重离子放疗系统的开启与关闭延迟，对两种实验方法进行比较，评估SGRT-质子重离子门控系统的延迟性能，为该技术的应用提供依据。开展两种测量：其一为PPL胶片法，质子束穿越1.5 mm直径的开孔挡铅，在胶片上呈现包含延迟特性的条带状图案，使用扫描仪以0.10 mm分辨率分析胶片条带；其二为高速相机-探测器法，以240 帧/s的高速相机拍摄到达门控条件的时间与探测器接收辐射信号的时间差，计算开启与关闭延迟。本研究通过两种不同的实验方法对门控延迟进行端到端测量，并以合成不确定度进行交叉验证测量结果。采用胶片法与相机-探测器法测得的门控开启延迟分别为79 ms±10 ms和67 ms±10 ms；对应的门控关闭延迟分别为101 ms±9 ms和129 ms±5 ms。该SGRT-质子重离子呼吸门控系统满足我院临床需求。本研究论证了多方法交叉验证门控延迟的可行性和必要性，为SGRT在粒子放疗中的推广与验收提供了量化依据。
- 质子放疗 /
- 光学体表监测 /
- 呼吸门控 /
- 门控延迟 /
- 多方法验证
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

HTML全文

图 1 胶片法门控延迟测量装置

Figure 1. Measurement device of gating delay based on the film method

下载: 全尺寸图片幻灯片

图 2 高速相机-探测器法门控延迟测量装置现场图

Figure 2. Photograph of the setup for gating delay measurement using the camera-based method

下载: 全尺寸图片幻灯片

图 3 胶片法束流门控延迟测量示例

Figure 3. Example of measuring gating latency using the film method

下载: 全尺寸图片幻灯片

图 4 胶片法与相机–探测器法测量门控开启与关闭延迟，以散点与均值±合成不确定度表现

Figure 4. Gate-on and gate-off latencies measured by the film and camera–detector methods, presented as scatter with mean ± combined uncertainty

下载: 全尺寸图片幻灯片

表 1 胶片法与相机法的B类典型最大误差估算

Table 1. Typical maximum type B uncertainty estimation for the film method and the camera-detector method

method	uncertainty component	label	typical maximum error estimation
film method	OD 50% criterion	a₁	±0.2 mm
	scanning resolution error	a₂	±0.1 mm
	film development uncertainty	a₃	±0.5 mm
	motion platform repeatability	a₄	±0.2 mm
camera-detector method	nominal frame rate error	a₅	±0.1 ms
	frame interval jitter	a₆	±0.1 ms
	LED indicator delay	a₇	±4 ms
	discrepancy between resonance midpoint and LED-on criterion	a₈	±4.18 ms (1 frame)

下载: 导出CSV

表 2 胶片法与相机-探测器法测量门控延迟的均值和不确定度统计

Table 2. Statistics of the mean and uncertainty for gating latency measured by the film method and the camera–detector method

item	method	standard deviation/ms	type A uncertainty $ {u}_{\mathrm{A}} $/ms	type B uncertainty $ {u}_{\mathrm{B}} $/ms	mean ± combined uncertainty/ms
beam-on gating latency	camera–detector method	28	9	3	67±10
beam-on gating latency	film method	2	1	10	79±10
beam-off gating latency	camera–detector method	13	4	3	129±5
beam-off gating latency	film method	8	5	7	101±9

下载: 导出CSV

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