无需引入空间变化权重因子的反向投影-滤波重建。

Backprojection-filtration reconstruction without invoking a spatially varying weighting factor.

机构信息

Department of Radiology, The University of Chicago, 5841 South Maryland Avenue, Chicago, Illinois 60637, USA.

出版信息

Med Phys. 2010 Mar;37(3):1201-9. doi: 10.1118/1.3285041.

DOI:10.1118/1.3285041

PMID:20384257

原文链接:https://pmc.ncbi.nlm.nih.gov/articles/PMC2837731/

Abstract

PURPOSE

To develop a backprojection-filtration (BPF) algorithm with improved noise properties over the existing BPF algorithm through utilizing (approximate) redundant information in circular cone-beam or fan-beam scans.

METHODS

The backprojection steps in the existing filtered-backprojection (FBP) and BPF algorithms for fan-beam and cone-beam projections invoke spatially varying weighting factors, which may not only increase the computational load in image reconstruction but also, more importantly, result in reconstruction artifacts. Redundant information in fan-beam projections has been exploited for eliminating the weighting factor in the existing FBP algorithm. However, the new FBP algorithm cannot be applied to image reconstruction in a region of interest from transversely truncated data. In this work, the authors identify approximate data redundancy in circular cone-beam projections and propose a new BPF algorithm in which the approximate data redundancy is exploited for eliminating the spatially varying weighting factor in the existing BPF algorithm.

RESULTS

The authors have implemented and evaluated the proposed BPF algorithm in numerical studies of reconstructing 3D images from both the nontruncated and truncated projection data in a circular cone-beam scan. The results of numerical studies demonstrate that the proposed BPF algorithm retains the resolution property of the existing BPF algorithm, and that it can also reconstruct accurately ROI images from truncated data. More importantly, the results also indicate that the proposed BPF algorithm not only is computationally more efficient but also yields generally lower image variances than the existing BPF algorithm.

CONCLUSIONS

A BPF algorithm was proposed that not only retains the desirable properties of the existing BPF algorithm but also possesses improved computational and noise properties over the latter.

摘要

目的

通过利用圆锥形束或扇形束扫描中的（近似）冗余信息，开发一种在噪声特性上优于现有反向投影滤波（BPF）算法的反向投影滤波算法。

方法

扇形束和锥形束投影中现有滤波反向投影（FBP）和 BPF 算法的反向投影步骤调用空间变化的加权因子，这不仅会增加图像重建的计算负担，而且更重要的是会导致重建伪影。扇形束投影中的冗余信息已被用于消除现有 FBP 算法中的加权因子。然而，新的 FBP 算法不能应用于从横向截断数据中感兴趣区域的图像重建。在这项工作中，作者确定了圆形锥形束投影中的近似数据冗余，并提出了一种新的 BPF 算法，其中利用近似数据冗余来消除现有 BPF 算法中的空间变化加权因子。

结果

作者已经在数值研究中实现并评估了从非截断和截断的圆形锥形束扫描的投影数据中重建 3D 图像的建议 BPF 算法。数值研究的结果表明，建议的 BPF 算法保留了现有 BPF 算法的分辨率特性，并且还可以从截断数据准确重建 ROI 图像。更重要的是，结果还表明，建议的 BPF 算法不仅在计算上更有效，而且通常比现有 BPF 算法产生更低的图像方差。