CT滤波反投影算法重建精度研究

发布时间：2018-03-06 22:06

本文选题：短扫描　切入点：滤波反投影　出处：《中北大学》2017年硕士论文　论文类型：学位论文

【摘要】：锥形束CT具有射线利用率高、扫描时间短、纵向分辨率高等优点,因此被广泛应用于实际。锥形束CT重建算法中滤波反投影算法由于数学形式简单,易实现,得到了广泛应用。但是受实际应用条件的限制,随着扫描半径的减小,锥角增大,重建质量会下降。基于这个问题,本文主要研究内容如下:(1)首先研究了扫描半径对扇形束FBP算法重建精度的影响,实验结果表明,扫描半径越大,重建图像质量越好;接着研究了加权函数对重建精度的影响,实验结果表明常数0.5加权比一般加权误差更大。同时将以上结论推广到锥束FDK算法。(2)平行重排(PFDK)算法是FDK算法的一种推广,针对FDK算法随着锥角增大重建精度下降的问题,给出了一种三维加权PFDK图像重建算法,并研究了重排过程中径向插值间隔对重建图像质量的影响,分别采用三种不同插值总数(插值间隔分别是1单位,0.5单位,0.25单位)重排数据。实验结果表明给出的三维加权PFDK算法可有效减少锥角对重建结果的影响,且当采用2倍插值总数时重建结果较好。
[Abstract]:Conical beam CT has the advantages of high ray utilization, short scanning time and high longitudinal resolution, so it is widely used in practice. Because of its simple mathematical form, filtering backprojection algorithm is easy to realize in conical beam CT reconstruction. It has been widely used, but limited by the practical application conditions, with the decrease of scanning radius, the conical angle increases and the reconstruction quality decreases. The main contents of this paper are as follows: firstly, the influence of scanning radius on the reconstruction accuracy of sector beam FBP algorithm is studied. The experimental results show that the larger the scanning radius is, the better the reconstructed image quality is, and then the influence of weighting function on the reconstruction accuracy is studied. The experimental results show that the constant 0.5 weighted error is greater than the general weighting error. At the same time, the above conclusion is extended to the cone-beam FDK algorithm. The parallel rearrangement PFDK) algorithm is a generalization of the FDK algorithm. In view of the problem that the accuracy of the FDK algorithm decreases with the increase of the cone angle, In this paper, a 3D weighted PFDK image reconstruction algorithm is presented, and the effect of radial interpolation interval on image quality during rearrangement is studied. The data are rearranged by three different interpolation totals (interpolation interval is 1 unit / 0. 5 unit / 0. 25 unit). Experimental results show that the proposed 3D weighted PFDK algorithm can effectively reduce the effect of cone angle on the reconstruction results. And the reconstruction result is better when the total number of interpolation is 2 times.
【学位授予单位】：中北大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TP391.41

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