北京航空航天大学学报 ›› 2021, Vol. 47 ›› Issue (6): 1199-1209.doi: 10.13700/j.bh.1001-5965.2020.0126

• 论文 • 上一篇    下一篇

基于加权全变差最小化的中子外部CT重建算法

林强1, 杨民1, 张晓敏1, 唐彬2, 刘斌2   

  1. 1. 北京航空航天大学 机械工程及自动化学院, 北京 100083;
    2. 中国工程物理研究院 核物理与化学研究所, 绵阳 621900
  • 收稿日期:2020-04-07 发布日期:2021-07-06
  • 通讯作者: 杨民 E-mail:minyang.ndt@buaa.edu.cn
  • 基金资助:
    国家自然科学基金(11675012,U1730116);核安全项目(41426020401)

Neutron exterior CT reconstruction algorithm based on weighted total variation minimization

LIN Qiang1, YANG Min1, ZHANG Xiaomin1, TANG Bin2, LIU Bin2   

  1. 1. School of Mechanical Engineering and Automation, Beihang University, Beijing 100083, China;
    2. Institute of Nuclear Physics and Chemistry, China Academy of Engineering Physics, Mianyang 621900, China
  • Received:2020-04-07 Published:2021-07-06
  • Supported by:
    National Natural Science Foundation of China (11675012, U1730116); Nuclear Safety Project (41426020401)

摘要: 针对中子外部CT检测需求,提出了基于加权方向全变差(WDTV)最小化的中子外部CT重建算法。首先,利用平行束数据对称性原理将正弦图中旋转中心另一侧缺失的投影数据进行补充;其次,采用传统FBP算法进行了外部CT扫描模式下的CT重建。为了抑制传统FBP、SART算法重建图像中径向边缘伪影,采用WDTV算法计算沿径向和周向方向的局部方向差分并作加权和。另外,在重建模型的WDTV项中引入2个权重参数以控制径向边缘和切向边缘的不同响应强度。最后,采用所提算法研究了重建图像质量与投影数据量的关系。计算机仿真和真实冷中子实验表明:基于WDTV最小化的中子外部CT重建算法能够有效抑制径向边缘伪影,获得高质量重建图像。

关键词: 成像系统, 中子断层成像, 外部CT扫描, 加权方向全变差(WDTV), 迭代重建

Abstract: Aimed at the requirements of the exterior CT inspection using neutron beam, an exterior CT reconstruction algorithm based on Weighted Directional Total Variation (WDTV) minimization is proposed. We first use the symmetry principle of parallel beam data to supplement the missing projection data that are on the other side of the rotation center in the sinogram. Then the FBP algorithm is used for the reconstruction under the exterior CT scanning. In order to reduce artifacts along the radial direction in the images reconstructed by the conventional FBP and SART algorithms, we choose radial direction and angular direction to calculate the local directional difference in the WDTV algorithm and then calculate the weighted sum of these two directional differences. In addition, we introduce two weight parameters into the WDTV reconstruction model to control the different edge responses' strength along radial edges and tangential edges. The relationship between the quality of reconstructed images and the amount of projection data is studied by using the proposed reconstruction algorithm. Computer simulation and real cold neutron experiments indicate that the proposed reconstruction algorithm can effectively suppress the image artifacts along the radial direction and thus high-quality reconstruction images can be obtained.

Key words: imaging systems, neutron computed tomography, exterior CT scanning, Weighted Directional Total Variation (WDTV), iterative reconstruction

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