摘要
康普顿成像是直观感知核辐射的探测技术之一,但因受限于探测器体积和成像事例的类型,能量范围通常为0.3~3 MeV,难以在对天然核素γ成像的基础上同时兼顾能量分布在3~7 MeV的瞬发γ成像应用.覆盖0.3~7 MeV范围的宽能域γ成像是扩展核辐射探测与成像应用领域的重要发展方向之一,基于两次散射的三层探测器结构是一种极具潜力的实现方案,其中探测器的设计与构建是该方案的基础与关键核心.考虑系统成本和扩展灵活性等因素,本文选用硅光电倍增管(SiPM)阵列和钆镓铝石榴石(GAGG:Ce)阵列作为探测器材料.根据三层探测器的成像事例要求,分析每层探测器内的作用事例类型特征;并基于Geant4蒙特卡罗模拟平台构建包含材料光学参数的仿真模型,通过设置物理过程与两种信息提取方式,对比研究了不同几何参数情形下的探测器位置散点图和探测器内作用事例类型统计结果.根据仿真设计,制备了由像素数为15×15,像素大小为3.2 mm×3.2 mm,厚度分别为3和10 mm的GAGG阵列和1.25 mm厚度光导组成的两种规格SiPM探测器模块,并基于电子学读出系统评估了探测器模块的性能.结果表明, 3 mm厚度的散射探测器与10 mm厚度的吸收探测器均可清晰分辨15×15像素上的作用位置,平均峰谷比分别为9.77和11.85;全部像素的662 keV平均能量分辨率分别可达7.21%和8.35%,具有较好的位置与能量分辨能力.本文所建立的仿真模型,分析结果以及所研制的探测器模块,为三层探测器系统构建提供了重要依据,并为实现宽能域γ成像奠定了科学技术基础.
Compton imaging is a technology to detect nuclear radiation intuitively. Due to the limitations of detector volume and types of imaging events, the energy range of traditional Compton imaging is usually 0.3–3 Me V. It is difficult to consider the application of prompt γ imaging with an energy distribution of 3–7 Me Von the basis of natural nuclide imaging. One of the important development directions to expand the application fields of nuclear radiation detection and imaging is gamma imaging with a wide-energy range covering 0.3–7 Me V. A three-layer detector structure based on double scattering is a potential implementation scheme in which the design and construction of the detector are the foundation and core. Considering the system cost and expansion flexibility, a silicon photomultiplier(Si PM) array and a gadolinium gallium aluminum garnet(GAGG:Ce) array are selected as detector materials in this paper. According to the requirements of imaging events for three-layer detectors, the characteristics of interaction events in each layer of the detector are analyzed. A simulation model including optical parameters of materials is established on the Geant4 Monte-Carlo simulation platform. The position maps of detectors and statistical results of interaction events in detectors with different geometric parameters are compared by setting up the physical process and two information extraction methods. According to the simulation design, two kinds of Si PM detector modules are composed of a GAGG array with a pixel number of 15×15, pixel size of 3.2 mm×3.2 mm, and thickness of 3 and 10 mm, respectively. The thickness of the light guide between the GAGG and Si PM arrays is1.25 mm. The performance of two detector modules is evaluated based on the electronic readout system. The results show that the scatterer detector with a thickness of 3 mm and the absorber detector with a thickness of 10 mm can clearly distinguish the interaction position on 15×15 pixels. The average peak-to-valley ratio is 9.77 and 11.85, resp
作者
张济鹏
马新华
张斌
肖雄
李京伦
雷文明
赵玮
艾宪芸
ZHANG JiPeng;MA XinHua;ZHANGG Bin;XIAO Xiong;LI JingLun;LEIWenMing;ZHAO Wei;AI XianYun(State Key Laboratory of NBC Projection for Civilian,Beijing 102205,China)
出处
《中国科学：技术科学》
EI
CSCD
北大核心
2024年第1期31-42,共12页
Scientia Sinica(Technologica)
基金
国家自然科学基金(批准号:12205372)
国家重点实验室科研基金(编号:SKLNBC2021-05)资助项目。
关键词
宽能域
康普顿成像
蒙特卡罗仿真
SiPM探测器
闪烁体阵列
wide-energy range
Compton imaging
Monte Carlo simulation
silicon photomultiplier detector
scintillator array
