摘要
康普顿成像技术是近年新兴的一种辐射热点定位技术,其无需准直,视野广,效率高,应用前景广阔。针对核设施热点定位需求,采用两块像素型碲锌镉(Cadmium Zinc Telluride,CZT)探测器,基于专用读出芯片(Application Specific Integrated Circuit,ASIC)的读出电子学系统,结合列表模式期望最大化极大似然(Listmode Maximum Likelihood Expectation Maximization,LM-MLEM)图像重建算法研制了一套双层分离式康普顿相机。采用^(137)Cs点源对该系统的成像性能开展了实验测试,并对探测器层间距、吸收层面积等成像性能影响参数展开了优化研究,最后通过移动探测器的测量位置实现了对放射源的远场三维成像功能测试。该系统优势在于其结构可调性,探测器成本低,读出电子学相对简单,成像视野范围宽于传统γ相机,测试结果表明:系统的能量分辨率约为3%(FWHM@662 keV),能确定5 m外的^(137)Cs点源三维位置信息,优化后的系统前锥角θ和侧向方位角φ的角分辨率约为10°。
[Background]Compton imaging technology is a new radiation hotspot location technology that does not require collimation and has a wide field of view,high efficiency,and broad application prospects.With the development of nuclear technology,Compton cameras with the above-mentioned advantages have a wide range of applications not only in the nuclear industry but also in the field of nuclear medicine,hence recently become a popular research field worldwide.[Purpose]This study aims to develop a double-layer separated Compton camera for far-field imaging of specific radiation scenes in nuclear facilities.[Methods]First of all,two pixel-type cadmium zinc telluride(CZT)detectors and an application-specific integrated circuit(ASIC)-based readout electronics system were adopted for the development of a double-layer separated Compton camera.A list-mode maximum likelihood expectation maximization(LM-MLEM)image reconstruction algorithm was implemented in the host computer software.Then,^(137)Cs point source was used for experimental test of imaging performance of the system,and the parameters affecting the imaging performance,such as the detector layer spacing and area of the absorption layer,were optimized.Finally,far-field three-dimensional imaging of the radiation source was performed by moving the measuring position of the detector.[Results]The test results show that the energy resolution of the CZT detectors is approximately 3%(FWHM@662 keV),which can determine the location of the point source at a distance of 5 m,and the angular resolution forθandφdirections of the optimized system is approximately 10°.[Conclusions]Doublelayer separated Compton camera of this study has advantages of adjustable structure,low detector cost,relatively simple readout electronics,and wide imaging field of view.The angular resolution of this double-layer separated Compton camera can be improved by proper adjustment of the imaging influence parameters(such as layer spacing and the area of the absorption layer).
作者
王薇
李兴隆
吴建华
庞洪超
骆志平
WANG Wei;LI Xinglong;WU Jianhua;PANG Hongchao;LUO Zhiping(China Institute of Atomic Energy,Department of Nuclear Security,Beijing 102413,China)
出处
《核技术》
CAS
CSCD
北大核心
2023年第3期42-51,共10页
Nuclear Techniques
