光栅相衬CT中吸收信号环形伪影的去除方法  

Method for removing ring artifacts of absorption signal in grating-based phase contrast CT

作　　者：杜天宇 高昆[1] 吴朝[1] DU Tianyu;GAO Kun;WU Zhao(National Synchrotron Radiation Laboratory,University of Science and Technology of China,Hefei 230029,China)

机构地区：[1]中国科学技术大学国家同步辐射实验室,安徽合肥230029

出　　处：《量子电子学报》2023年第1期40-47,共8页Chinese Journal of Quantum Electronics

基　　金：国家自然科学基金(11805205),国家重大科研装备研制项目(CZBZDYZ20140002)。

摘　　要：提出一种光栅X射线相衬断层扫描中吸收信号环形伪影的去除方法。该方法采用正弦图域和重建图域结合的处理算法。对于弱伪影,通过正弦图域的排序和滤波去除。而对于强伪影,首先根据环形伪影在极坐标系的表现,计算残差图像,转换到笛卡尔坐标系得到伪影像素和样品的边界;进而使用基于机器学习的图像分割方法获取每一类样品的分布,同时为了保护边界信息,通过形态学操作获得样本的内部区域;最后再利用残差图像的分布特征定位伪影像素,并使用临近非伪影像素均值替代。实验结果表明该方法可以在不破坏样品边界的前提下有效地去除图像中的环形伪影。A method for removing ring artifacts of absorption signals in grating-based X-ray phase contrast tomography is proposed.In the method,a processing algorithm combining sinogram-domain with reconstruction image-domain is adopted.For weak artifacts,sorting and filtering are performed in the sinogram-domain.While for strong artifacts,the residual image is calculated firstly according to the performance of ring artifacts in the polar coordinate system,which is converted to Cartesian coordinate system to obtain the artifacts and the sample boundaries.Then an image segmentation method based on machine learning is used to obtain the distribution of each type of samples,and in order to protect the boundary information,the internal region of the samples is obtained through morphology operation.Finally,the distribution features of the residual images are used to locate the artifact pixels,and the mean value of adjacent non-artifact pixels are used to replace them.The experimental results show that this method can effectively remove the ring artifacts in the image without destroying the sample boundaries.

关 键 词：层析图像处理 光栅X射线成像 相位衬度断层扫描 环形伪影 

分 类 号：O434.19[机械工程—光学工程]