Test of Compton camera components for prompt gamma imaging at the ELBE bremsstrahlung beam
Test of Compton camera components for prompt gamma imaging at the ELBE bremsstrahlung beam
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DOI：
10.1088/1748-0221/9/05/p05002
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发表时间：
2014-05-01
影响因子：
1.3
通讯作者：
Pausch, G.
中科院分区：
文献类型：
--
作者：
Hueso-Gonzalez, F.;Golnik, C.;Pausch, G.
在离子束治疗的背景下，粒子范围验证是治疗质量保证的主要挑战。一种方法是测量组织照射产生的瞬发伽马射线。基于多个位置敏感伽马射线探测器的康普顿相机与成像算法一起有望重建与剂量分布相关的即时伽马射线发射密度图。 OncoRay 和 Helmholtz-Zentrum Dresden-Rossendorf (HZDR) 正在开发一种康普顿相机装置，该装置由两个散射平面组成：两个 CdZnTe (CZT) 十字条探测器和一个由一个 Lu2SiO5 (LSO) 块探测器组成的吸收体。数据采集基于 VME 电子设备，并由在 ROOT 框架上开发的软件处理。该装置已在 HZDR 的线性电子加速器 ELBE 上进行了测试，该加速器在本实验中用于产生能量高达 12.5 MeV 且重复频率为 13 MHz 的束状轫致辐射光子。它们的光谱与临床环境中瞬发伽马射线预期的形状相似，并且通量也随着加速器频率聚集。对不同能量范围内的 CZT 探测器的电荷共享效应进行了定性研究。对 LSO 探测器像素辨别分辨率进行了分析，结果表明高能沉积有改善的趋势。用于背景抑制的脉冲瞬发光子和测量的探测器信号之间的时间相关性显示，CZT 探测器的 FWHM 为 3 ns，LSO 探测器的时间分辨率为 2 ns。 LSO 探测器采用时间游走校正和逐像素校准，其分辨率提高至 630 ps。总之，探测器设置适用于脉冲临床粒子加速器中的时间分辨背景抑制。正在进行的任务是与模拟的定量比较和成像算法的测试。质子加速器的实验也已经进行，目前正在分析中。
In the context of ion beam therapy, particle range verification is a major challenge for the quality assurance of the treatment. One approach is the measurement of the prompt gamma rays resulting from the tissue irradiation. A Compton camera based on several position sensitive gamma ray detectors, together with an imaging algorithm, is expected to reconstruct the prompt gamma ray emission density map, which is correlated with the dose distribution. At OncoRay and Helmholtz-Zentrum Dresden-Rossendorf (HZDR), a Compton camera setup is being developed consisting of two scatter planes: two CdZnTe (CZT) cross strip detectors, and an absorber consisting of one Lu2SiO5 (LSO) block detector. The data acquisition is based on VME electronics and handled by software developed on the ROOT framework. The setup has been tested at the linear electron accelerator ELBE at HZDR, which is used in this experiment to produce bunched bremsstrahlung photons with up to 12.5 MeV energy and a repetition rate of 13 MHz. Their spectrum has similarities with the shape expected from prompt gamma rays in the clinical environment, and the flux is also bunched with the accelerator frequency. The charge sharing effect of the CZT detector is studied qualitatively for different energy ranges. The LSO detector pixel discrimination resolution is analyzed and it shows a trend to improve for high energy depositions. The time correlation between the pulsed prompt photons and the measured detector signals, to be used for background suppression, exhibits a time resolution of 3 ns FWHM for the CZT detector and of 2 ns for the LSO detector. A time walk correction and pixel-wise calibration is applied for the LSO detector, whose resolution improves up to 630 ps. In conclusion, the detector setup is suitable for time-resolved background suppression in pulsed clinical particle accelerators. Ongoing tasks are the quantitative comparison with simulations and the test of imaging algorithms. Experiments at proton accelerators have also been performed and are currently under analysis.