高压电缆源平移扫描CT高效重建算法  

High-efficiency Reconstruction Algorithm of Source Translation ScanComputed Tomography for High-voltage Cable

作　　者：倪松 陈杰 余海军 段晓礁 陈大兵 刘建军 NI Song;CHEN Jie;YU Haijun;DUAN Xiaojiao;CHEN Dabing;LIU Jianjun(Chongqing Zhence Science and Technology Co.,Ltd.,Chongqing 401332,China;Research Institute,State Grid Jiangsu Electric Power Co.,Ltd.,Nanjing 211103,China)

机构地区：[1]重庆真测科技股份有限公司,重庆401332 [2]国网江苏省电力有限公司电力科学研究院,南京211103

出　　处：《光子学报》2023年第7期131-141,共11页Acta Photonica Sinica

基　　金：国家电网有限公司科技项目(No.5500-202118134A)。

摘　　要：为提高在役高压电缆X射线扫描图像重建速度,结合传统的滤波反投影算法,提出基于数据平滑的局部扫描重建算法。分析了源直线扫描局部计算机断层成像方法存在的有限角和数据截断问题,提出数据平滑方式解决方法。主要途径是利用余弦函数沿探测器方向和射线源方向分别进行数据平滑插值,避免投影数据值在这两个方向上突然降为零,起到抑制截断伪影和有限角伪影的作用。实验证明,所提方法能有效抑制图像伪影,有利于电缆阻水缓冲层缺陷识别。相较于原有的联合迭代重建算法,该方法缩短了重建时间且图像重建质量相当;相较于传统滤波反投影算法,重建图像质量提高但重建耗时基本一致。Cross-linked Polyethylene(XLPE)cable is widely used in urban power supply systems because of its excellent performance.Its inner structure-the water-blocking buffer layer-is prone to suffer from ablation defects after a long time of working,which will threaten the safety of the city′s power supply.Therefore,the accurate detection of such cable defects is an urgent problem to be solved.In our previous work,we proposed a Local Source-translation Computed Tomography(L-STCT)method for cable detection.This method focuses on scanning part of the cable around the water-blocking buffer layer,and can intuitively observe the internal structure and identify defects with the reconstructed image.However,the used reconstruction method-Simultaneous Iterative Reconstruction Technique(SIRT)-requires massive iterations for final images,lowering reconstruction efficiency.To meet the high-efficiency reconstruction in engineering applications,we propose a Local-detecting Filtered Backprojection(LFBP)method in this paper,as the analytical method is much fast for image reconstruction.The typical analytic algorithm-Filtered Backprojection(FBP)-requires complete and detruncated projection for artifacts-free reconstruction.As L-STCT scans only part of the cable,the X-ray beam cannot cover the entire object,resulting in projection truncation.At the same time,limited source trajectory and detector width cannot achieve at least 180°angular coverage,resulting in projection missing.The L-STCT scan suffers from the problems of projection truncation and limited-angle computed tomography.Performing analytic reconstruction with raw incomplete and truncated projection will produce severe artifacts,affecting defect identification.To suppress the potential artifacts,the projection smoothing method is introduced according to projection characteristics.Projection smoothing mainly uses the cosine function to interpolate data along the detector direction and source sampling direction respectively.At both ends of the detector,the new part of virtual da

关 键 词：计算机断层扫描 源直线扫描局部计算机断层成像 滤波反投影算法 数据平滑 有限角成像 数据截断 伪影抑制 

分 类 号：O434.19[机械工程—光学工程]