基于加权总差分最小化的中子稀疏投影计算机断层重建方法

Neutron Computed Tomography Reconstruction Method Using Sparse Projections Based on Weighted Total Difference Minimization

为提升高噪声稀疏角度投影条件下中子计算机断层扫描(CT)质量,提出同时迭代重建方法(SIRT)与加权总差分最小化(WTDM)相结合的迭代重建方法(SIRT-WTDM)。在有无噪声情况下比较代数重建算法、联合代数重建算法及同时迭代重建算法的重建图像,证明了SIRT迭代重建具有较高的图像重建精度与较强的抗噪声性能,因此将SIRT作为高噪声中子投影图像CT迭代重建算法的保真项。考虑到对图像梯度稀疏性与连续性的约束,中子CT迭代重建方法的正则化约束项采用WTDM方法。由Shepp-Logan模体与真实冷中子层析扫描数据验证可知,在极端稀疏角度投影条件下,SIRT-WTDM可获得较好的重建效果。

Aiming at improving the quality of the neutron computed tomography(CT) reconstructed from high noise and sparse angle projection data, an iterative reconstruction method(SIRT-WTDM) combined the simultaneous iterative reconstruction technique(SIRT) and weighted total difference minimization(WTDM) is successfully proposed. The reconstructed images obtained by algebraic reconstruction technique, simultaneous algebraic reconstruction technique, and SIRT are compared with or without the random noise in the projections, from which the SIRT method is proved to have higher reconstruction accuracy and stronger anti-noise ability. Therefore, the SIRT method is adopted as the fidelity term of the neutron CT iterative reconstruction method with high-noise projections. Considering the constraint to the sparsity and the continuity of the image gradient, the WTDM method is adopted as the regularization term of the neutron CT iterative reconstruction method. Under the condition of extreme sparse angle projections, the SIRT-WTDM can obtain the better reconstruction images, which has been proved by the Shepp-Logan simulated data and cold neutron CT scanning data.