1 简介
与传统计算机层析(CT)成像技术相比,能谱CT可在一次扫描中得到物体在不同能谱通道下的投影图像,这有利于区分物体的材质,提高信号噪声比.基于光子计数探测器的能谱CT是近年来成像领域研究的热点.由于能谱通道变窄,每个能谱通道内的噪声增加.为了有效降低通道内的噪声,采用基于全变分最小化的SplitBregman算法进行图像重建.根据重建模体的先验信息,进行能谱通道的划分;采用Split-Bregman算法对含噪声和稀疏角的能谱投影数据进行重建.仿真结果表明,基于Split-Bregman算法的能谱CT图像重建方法能够有效减少能谱通道内噪声的影响,满足物体材质区分的需求.
2 部分代码
% test_mrics.m by Tom Goldstein (tagoldst@math.ucla.edu)% This file is meant to demonstrate how to properly use mrics.m% When this script is run, it will first build a simple test image. The% method then builds a sampling matrix, R, with entries randomly chosen % to be 1 or 0. The compressed sensing data is then computed using the% folrmula F = R.*fft2(image). Gaussian noisy is added to the CS data.% Finally, the mrics method is used to reconstruct the image form the% sub-sampled K-Space data. N = 128; % The image will be NxNsparsity = .25; % use only 30% on the K-Space data for CS % build an image of a squareimage = zeros(N,N);image(N/4:3*N/4,N/4:3*N/4)=255; % build the sampling matrix, RR = rand(N,N);R = R<sparsity; % Form the CS dataF = R.*fft2(image);% Recover the imagerecovered = mrics(R,F, 1, 1, 1e-5,10, 4);% build a figure to display resultsfigure;subplot(2,2,1);imagesc(abs(image)); colormap('gray');title('Original');subplot(2,2,2);imagesc(abs(R)); colormap('gray');title('R');subplot(2,2,3);imagesc(abs(ifft2(F))); colormap('gray');title('Set unknown to 0');subplot(2,2,4);imagesc(abs(recovered)); colormap('gray');title('Split Bregman Recovery');
3 仿真结果
4 参考文献
[1]苟军年, 董海鹰. 基于Split Bregman算法的有限角度CT图像重建[J]. 兰州交通大学学报, 2018, 37(3):6.
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