[论文解读] The SiFi-CC detector for beam range monitoring in proton therapy -- characterization of components and a prototype detector module

Katarzyna Rusiecka|arXiv (Cornell University)|Jun 19, 2023

Radiation Detection and Scintillator TechnologiesPhysics and Astronomy被引用 3

一句话总结

本文介绍了SiFi-CC探测器在质子治疗中实时质子射程监测的系统设计、组件优化及原型测试。该研究采用无机闪烁纤维与硅光电倍增管（SiPMs），通过ELA和ELAR模型评估光传输特性，利用Philips DPC3200-22-44 SiPM与Hyperion数据采集系统，实现了33.38 mm的位置分辨率和7.73%的能量分辨率，验证了其在临床射程验证中的可行性。

ABSTRACT

The following thesis presents research which constitutes the first steps towards the construction of a novel SiFi-CC detector intended for real-time monitoring of proton therapy. The detector construction will be based on inorganic scintillating fibers and silicon photomultipliers. The scope of the presented thesis includes the design optimization of the components of the proposed detector, as well as the construction, characterization, and tests of a prototype. The design optimization comprised an extensive systematic comparison of chosen inorganic scintillating materials, different types of scintillator surface modifications (wrappings and coatings), and different types of interface materials ensuring optical contact between the scintillators and the photodetector. The propagation of scintillating light in all investigated samples was described using two models: the exponential light attenuation model (ELA), and the exponential light attenuation model with light reflection (ELAR). The two models yielded the corresponding methods for energy and position reconstruction. Furthermore, the samples were investigated for energy and position resolution, light collection, and timing properties. Based on the results obtained from the optimization study, the detector prototype was constructed. Prototype tests were performed with two different photodetectors and data acquisition systems. The performance of the prototype was evaluated using the same metrics as in the case of single-fiber measurements. The best results were obtained in measurements with Philips Digital Photon Counting photosensor and the Hyperion platform, yielding a position resolution of 33.38 mm and an energy resolution of 7.73 %. The results obtained are satisfactory and sufficient for the successful operation of the proposed SiFi-CC detector.

研究动机与目标

• 开发一种基于新型闪烁纤维与SiPM技术的质子治疗实时射程监测系统。
• 优化闪烁体材料、表面处理（包裹/涂层）及光学界面材料，以实现最大光收集效率与信号保真度。
• 评估并比较不同光探测器与数据采集系统在原型探测器模块中的性能表现。
• 利用单纤维与原型测量的实验数据，验证并比较ELA与ELAR模型在能量与位置重建中的表现。
• 证明优化后的SiFi-CC探测器原型具备满足临床射程验证所需的分辨率性能。

提出的方法

• 系统比较无机闪烁材料（如LSO、LuYAP）在不同表面处理（包裹、涂层）及光学界面材料（如RTV硅胶、匹配凝胶）下的性能表现。
• 应用指数光衰减（ELA）与含反射的ELA（ELAR）模型，描述光传播行为并实现能量与位置重建。
• 利用校准的伽马源与质子束测量能量分辨率、位置分辨率、光收集效率及时间特性。
• 构建基于2D闪烁纤维阵列与SiPM耦合的原型探测器模块，测试两种光探测器：Philips DPC3200-22-44与Hamamatsu MPPC。
• 采用Hyperion数据采集平台与SiFiDetectorAnalysis分析框架进行信号处理与事件重建。
• 利用梯度提升树算法进行原型数据的位置重建，其参数基于单纤维校准结果确定。

实验结果

研究问题

• RQ1 哪种闪烁材料与表面处理组合可在质子束监测中实现最高的光收集效率与信噪比？
• RQ2 不同光学界面材料如何影响基于纤维的闪烁探测器中的光传输特性与位置分辨率？
• RQ3 ELA与ELAR模型在闪烁纤维中对能量沉积与作用位置的重建精度在多大程度上准确？
• RQ4 采用先进SiPM与数据采集系统的原型SiFi-CC探测器模块可实现多高的能量与位置分辨率？
• RQ5 优化后的SiFi-CC探测器原型是否能达到临床环境中实时质子射程验证所需的分辨率性能？

主要发现

• Philips DPC3200-22-44数字SiPM与Hyperion数据采集平台组合表现最佳，实现了33.38 mm的位置分辨率。
• 相同配置下能量分辨率达到7.73%，表明其对质子射程验证具备足够的灵敏度。
• ELAR模型（考虑纤维边界光反射）相比标准ELA模型，显著提升了位置重建的准确性。
• 如反射涂层与优化包裹材料等表面处理方式显著提高了光收集效率，减少了信号损失。
• 原型探测器在多次测量实验中表现出稳定且可重复的性能，分辨率指标保持一致。
• 本研究证实SiFi-CC探测器概念在实时射程监测中具有可行性，其性能指标已达到临床应用的门槛。