高速中性子線を用いた高性能ＣＴ再構築アルゴリズムの開発

为了实现光学、x射线和中子等不同模态的超分辨率计算机断层扫描（CT），提出了一种线性+旋转扫描方法，在每个视角下收集更多的投影数据进行图像重建。我们首先以快中子CT为研究对象，利用2cm×2cm×5cm (T)像素级的像素型快中子成像探测器。我们编写了用面积模型实现系统矩阵计算的代码。投影数据和系统矩阵的重建结果初步表明，线性+旋转扫描比旋转扫描能提高CT图像的质量。为了进一步验证所提出的线性+旋转扫描方法在提高CT图像质量方面的有效性，在RIKEN加速器驱动的紧凑中子源（RANS）上进行了快中子CT实验。对1.5cm厚亚克力条的成功识别表明线性扫描方法在单幅投影图像中效果良好。由于目前像素型快中子成像探测器的CT图像质量较差，难以对其空间分辨率进行评价，因此采用热中子CT对CT图像的空间分辨率进行评价。利用全宽半最大值（FWHM）对目标锐利边缘进行空间分辨率评价，并与仿真结果相结合。我们在第三届国际能源与环境先进测量、分析与控制学术研讨会（AMACEE2020-WEB）上做了关于像素型快中子成像探测器性能评价的口头报告（特邀报告）。

To realize the super resolution computer tomography (CT) with different modalities, such as optics, X-rays and neutrons, a linear + rotation scan method is proposed to collect more projection data in each view angle for image reconstruction. We firstly set fast neutron CT as the research object, which utilizing a pixel-type fast neutron imaging detector with 2cm×2cm×5cm (T) pixel size. We have made the code to realize calculation of system matrix with area model. Reconstruction results with projection data and system matrix preliminary indicates linear + rotation scan method can improve the quality of CT image compared with rotation scan.To further validate the effectiveness of the proposed linear + rotation scan method in improving the quality of CT image, fast neutron CT experiment has been done at RIKEN Accelerator-driven compact Neutron Source (RANS). Successful identification of 1.5cm thick acrylic bar indicates linear scan method works well in one projection image.As the spatial resolution of CT image with current pixel-type fast neutron imaging detector is hard to be evaluated due to its weak image quality, thermal neutron CT is used to evaluate the spatial resolution of CT image. Evaluation of spatial resolution through Full Width Half Maximum (FWHM) for sharp edge of object with simulation results has been realized.We have made an oral presentation (invited talk) about evaluation of performance of pixel-type fast neutron imaging detector on 3rd International Symposium on Advanced Measurement, Analysis and Control for Energy and Environment (AMACEE2020-WEB).