Penalized weighted least-squares approach to sinogram noise reduction and image reconstruction for low-dose X-ray computed tomography
Penalized weighted least-squares approach to sinogram noise reduction and image reconstruction for low-dose X-ray computed tomography
复制标题
DOI：
10.1109/tmi.2006.882141
复制
发表时间：
2006-10-01
影响因子：
10.6
通讯作者：
Liang, Zhengrong
中科院分区：
文献类型：
--
作者：
Wang, Jing;Li, Tianfang;Liang, Zhengrong
重建低剂量X射线计算机断层扫描（CT）图像是一个噪声问题。这项工作研究了惩罚加权最小二乘（PWLS）的方法来解决这个问题，在两个维度，其中WLS认为一阶和二阶噪声矩和惩罚模型信号的空间相关性。三种不同的实施方案进行了研究的PWLS最小化。一种是利用马尔可夫随机场（MRF）吉布斯函数来考虑附近探测器箱和正弦图空间中的投影视图之间的空间相关性，并通过迭代高斯-赛德尔算法来最小化PWLS成本函数。另一种方法采用Karhunen-Loeve（KL）变换对附近视图之间的数据信号进行去相关，并通过解析计算自适应地最小化每个KL分量的PWLS，其中附近箱之间的空间相关性由相同的吉布斯函数建模。第三种方法同样采用MRF Gibbs泛函对图像域像素间的空间相关性进行建模，并采用迭代逐次超松弛算法最小化PWLS。在这三种实现中，为MRF模型选择了二次函数正则化。幻影实验表明，这三个PWLS为基础的方法在抑制噪声引起的条纹文物和保留在重建图像的分辨率方面的性能相当。计算机模拟与体模实验一致的噪声分辨率的权衡和可检测性在低对比度环境。KL-PWLS实现在高分辨率动态低剂量CT成像的计算方面可能具有优势。
Reconstructing low-dose X-ray computed tomography (CT) images is a noise problem. This work investigated a penalized weighted least-squares (PWLS) approach to address this problem in two dimensions, where the WLS considers first- and second-order noise moments and the penalty models signal spatial correlations. Three different implementations were studied for the PWLS minimization. One utilizes a Markov random field (MRF) Gibbs functional to consider spatial correlations among nearby detector bins and projection views in sinogram space and minimizes the PWLS cost function by iterative Gauss-Seidel algorithm. Another employs Karhunen-Loeve (KL) transform to de-correlate data signals among nearby views and minimizes the PWLS adaptively to each KL component by analytical calculation, where the spatial correlation among nearby bins is modeled by the same Gibbs functional. The third one models the spatial correlations among image pixels in image domain also by a MRF Gibbs functional and minimizes the PWLS by iterative successive over-relaxation algorithm. In these three implementations, a quadratic functional regularization was chosen for the MRF model. Phantom experiments showed a comparable performance of these three PWLS-based methods in terms of suppressing noise-induced streak artifacts and preserving resolution in the reconstructed images. Computer simulations concurred with the phantom experiments in terms of noise-resolution tradeoff and detectability in low contrast environment. The KL-PWLS implementation may have the advantage in terms of computation for high-resolution dynamic low-dose CT imaging.