脉冲射线源三维中子成像重建算法研究  

Three-dimensional Neutron Imaging Reconstruction Algorithms Research of Pulsed Radiation Sources

作　　者：盛亮[1] 张艳红[1] 高建鹏 李阳[1] 段宝军[1] 黑东炜[1] SHENG Liang;ZHANG Yanhong;GAO Jianpeng;LI Yang;DUAN Baojun;HEI Dongwei(State Key Laboratory of Intense Pulsed Radiation Simulation and Effect,Northwest Institute of Nuclear Technology,Xi'an 710024,China;Department of Engineering Physics,Tsinghua University,Beijing 100084,China)

机构地区：[1]西北核技术研究所强脉冲辐射环境模拟与效应国家重点实验室,西安710024 [2]清华大学工程物理系,北京100084

出　　处：《光子学报》2022年第3期76-87,共12页Acta Photonica Sinica

基　　金：国家自然科学基金(No.11575147);卓越青年基金(No.JQZQ021901)。

摘　　要：借鉴计算机层析成像方法,通过多角度成像的方式得到氘氚燃烧区三维分布信息。介绍了球谐函数分解、最大期望代数迭代两种具有代表性的极少角度三维图像重建算法,并提出将球谐函数分解重建结果作为最大期望代数迭代初始值的重建约束方法。该方法利用了激光、Z箍缩聚变靶具有一定球对称性的物理先验,既改善了球谐函数在极少角度投影重建表示能力不足、残影较大的缺点,又利用了最大期望算法局部最优的特点,可以将重建结果限制在物理似然域中,从而在一定程度上克服了极少角度投影三维重建解空间过大的问题。利用峰值信噪比、均方根误差、KL偏差等三种指标对重建结果进行了量化评价,结果表明球谐函数初值约束的最大期望代数迭代算法效果最好。Three-dimensional(3D)neutron imaging is the cutting-edge diagnostic method for pulsed radiation sources driven by laser or Z-pinch.Neutron images with different energies can accurately diagnose the spatial structure of the burning Deuterium-Tritium(DT)plasma and surrounding materials under high compression ratio,which is of great significance for improving the technical measures of compression symmetry,verifying the physical model and evaluating the ignition performance.Utilized the computed tomography method,3D information of the target internal structure can be acquired by multi-view neutron imaging method.Along with the limitations of current technology,there are great difficulties in pixel level accurate matching,high-precision time correlation and camera sensitivity difference correction between different imaging axes due to the high radiation intensities,short durations,and wide energy ranges of the pulsed radiation sources.Thus,only a limited number of axis can be implemented.Reconstructing 3D images from severely incomplete two-dimensional data is an ill-posed problem,which suffers from large solution space,artifacts and inability to maintain edge features.JIANG Shaoen et al developed a 3D reconstruction algorithm based on algebraic reconstruction techniques.VOLEGOV P L et al used an iterative Expectation-Maximization(EM)algorithm to reconstruct 3D neutron or X-ray sources.The algorithm reconstructed the main geometrical features of the source,but introduced artifacts affected by the angular distribution of projection directions.VOLEGOV P L et al later adopted Spherical Harmonic Decomposition(SHD)and Cylindrical Harmonic Decomposition(CHD)methods to the reconstruction of 3D radiation sources.While these analytical methods based on basis functions expansion were fast and could acquire the unique solution under certain conditions,their representation abilities were limited by the number of imaging axes and would produce artifacts related to the truncation of expansion order.In this paper,we introduce and re

关 键 词：三维图像重建 球谐函数分解 最大期望迭代算法 快中子成像 惯性约束聚变 

分 类 号：O536[理学—等离子体物理] TL81[理学—物理]