结合改进扩散和双边滤波的低剂量CT重建  

Combination of improved diffusion and bilateral filtering for low-dose CT reconstruction

作　　者：张鹏程[1] 张权[1] 张芳[1] 陈燕[1] 韩建宁[1] 郝慧艳[1] 桂志国[1,2] 

机构地区：[1]电子测试技术国家重点实验室(中北大学),太原030051 [2]仪器科学与动态测试教育部重点实验室(中北大学),太原030051

出　　处：《计算机应用》2016年第4期1100-1105,共6页journal of Computer Applications

基　　金：国家自然科学基金资助项目(61271357);山西省自然科学基金资助项目(2015011046);中北大学2013年校科学基金资助项目~~

摘　　要：针对低剂量计算机断层扫描(CT)重建图像时出现明显条形伪影的现象,提出一种结合非局部均值模糊扩散和扩展邻域双边滤波的中值先验(MP)重建算法。首先,使用基于非局部均值模糊扩散方法对中值先验分布的最大后验(MAP)重建算法进行改进,以减少重建图像中的噪声;然后,采用基于扩展邻域的双边滤波方法对重建图像进行处理,以保持图像的边缘和细节信息,进一步提高重建图像的信噪比。采用Shepp-Logan模型和胸腔模型来验证算法的有效性,实验结果表明,与滤波反投影(FBP)、中值根先验(MRP)、非局部均值模糊扩散的MP重建(NLMMP)算法和非局部均值双边滤波的MP重建(NLMBFMP)算法相比,所提新算法的归一化均方距离和均方绝对误差最小,且信噪比最高,分别为10.20 d B和15.51 d B。该重建算法可以在对重建图像进行降噪的同时保持了图像的边缘和细节信息,改善了低剂量CT图像质量退化的问题,获得高信噪比和高质量的重建图像。Median Prior（ MP） reconstruction algorithm combined with nonlocal means fuzzy diffusion and extended neighborhood bilateral filter was proposed to reduce the streak artifacts in low-dose Computed Tomography（ CT） reconstruction.In the new algorithm,the nonlocal means fuzzy diffusion method was used to improve the median of the prior distribution Maximum A Posterior（ MAP） reconstruction algorithm at first,which reduced the noise in the reconstruction image; then,the bilateral filtering method based on the expended neighborhood was applied to preserve the edges and details of the reconstruction image and improve the Signal-to-Noise Ratio（ SNR）. The Shepp-Logan model and the thorax phantom were used to test the effectiveness of the proposed algorithm. The experimental results show that the proposed method has the smaller values of the Normalized Mean Square Distance（ NMSD） and Mean Absolute Error（ MAE） and the highest SNR（ 10. 20 d B and 15. 51 d B,respectively） in the two experiment images,compared with Filtered Back Projection（ FBP）,Median Root Prior（ MRP）,Non Local Mean MP（ NLMMP） and Non Local Mean Bilateral Filter MP（ NLMBFMP） algorithms. The experimental results show that the proposed reconstruction algorithm can reduce noise while keeping the edges and details of the image,which improves the deterioration problem of the low-dose CT image and obtains the image with higher SNR and quality.

关 键 词：低剂量计算机断层扫描 非局部均值 模糊扩散 扩展邻域 双边滤波 

分 类 号：TP391.7[自动化与计算机技术—计算机应用技术]