Proton Radiography for a Small-Animal Irradiation Platform Based on a Miniaturized Timepix Detector
Proton Radiography for a Small-Animal Irradiation Platform Based on a Miniaturized Timepix Detector
复制标题
基于小型 Timepix 探测器的小动物辐照平台质子射线照相
DOI：
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发表时间：
2020
期刊：
影响因子：
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通讯作者：
K. Parodi
中科院分区：
文献类型：
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作者：
M. Würl;Katrin Schnürle;J. Bortfeldt;C. Oancea;C. Granja;E. Verroi;F. Tommasino;K. Parodi
治疗前的质子摄影和计算机断层扫描可以提高质子治疗的精度。介绍了一种用于小动物质子照相的紧凑型成像装置，该装置基于小型化的Timepix探测器，以及概念验证实验的结果。MiniPIX探测器被放置在带有10个不同组织等效插入物的µ-CT校准体模的后面。调整了70 MeV质子束的强度，以便能够分辨探测器上单个质子的像素信号簇。使用对各种集群属性的分析和事件过滤来抑制不需要的事件。使用基于蒙特卡罗模拟和测量的质子团簇的转换曲线，将所选团簇的能量沉积转换为被穿越材料的水当量厚度(湿)，然后穿过已知厚度的PMMA板。尽管系统低估了高达3%，但恢复的湿值与文献中的地面真实值很好地吻合。在体模-探测器距离为1-5厘米时，所获得的空间分辨率为0.3-0.7 mm。目前，对活体动物的适用性受到相对较长的采集时间的限制，每次X光成像最多20分钟。然而，这一障碍可以通过最新一代的探测器Timepx3来克服，允许处理更高的粒子率，因此需要更短的照射时间。
Pre-treatment proton radiography and computed tomography can improve precision of proton therapy. A compact imaging setup for small-animal proton radiography, based on a miniaturized Timepix detector is presented along with results from proof-of-concept experiments. The MiniPIX detector was placed behind a µ-CT calibration phantom with 10 different tissue-equivalent inserts. The intensity of the 70MeV proton beam was adjusted such that pixel signal clusters from individual protons on the detector could be resolved. Analysis and event filtering on various cluster properties were used to suppress unwanted events. The energy deposition of the selected clusters was converted to water-equivalent thickness (WET) of the traversed material using a conversion curve based on Monte Carlo simulations and measured clusters of protons after traversing PMMA slabs of known thickness. Despite a systematic underestimation of up to 3%, retrieved WET values are in good agreement with ground truth values from literature. The achieved spatial resolution ranges from 0.3 to 0.7 mm for phantom-detector-distances of 1 to 5 cm. Applicability to living animals is currently limited by the relatively long acquisition time of up to 20 minutes per radiography. This obstacle can however be overcome with the latest detector generation Timepix3, allowing to handle higher particle rates and thus requiring shorter irradiation times.