再次探讨组合平行束/锥束或扇束/锥束成像。

Revisit of combined parallel-beam/cone-beam or fan-beam/cone-beam imaging.

机构信息

Department of Engineering, Weber State University, Ogden, Utah 84408 and Utah Center for Advanced Imaging Research (UCAIR), Department of Radiology, University of Utah, Salt Lake City, Utah 84108.

出版信息

Med Phys. 2013 Oct;40(10):100701. doi: 10.1118/1.4820373.

DOI:10.1118/1.4820373

PMID:24089888

原文链接:https://pmc.ncbi.nlm.nih.gov/articles/PMC3785539/

Abstract

PURPOSE

This aim of this paper is to revisit the parallel-beam/cone-beam or fan-beam/cone-beam imaging configuration, and to investigate whether this configuration has any advantages.

METHODS

Twenty years ago, it was suggested to simultaneously use a parallel-beam (or a fan-beam) collimator and a cone-beam collimator to acquire single photon emission computed tomography data. The motivation was that the parallel-beam (or the fan-beam) collimator can provide sufficient sampling, while the cone-beam collimator is able to provide higher photon counts. Even with higher total counts, this hybrid system does not give significant improvement (if any) in terms of image noise and artifacts reduction. If a conventional iterative maximum-likelihood expectation-maximization algorithm is used to reconstruct the image, the resultant reconstruction may be worse than the parallel-beam-only (or fan-beam-only) system. This paper uses the singular value decomposition (SVD) analysis to explain this phenomenon.

RESULTS

The SVD results indicate that the parallel-beam-only and the fan-beam-only system outperform the combined systems.

CONCLUSIONS

The optimal imaging system does not necessary to be the one that generates the projections with highest signal-to-noise ratio and best resolution.

摘要

目的

本文旨在重新审视平行束/锥束或扇形束/锥束成像配置，并研究这种配置是否具有优势。

方法

二十年前，有人建议同时使用平行束（或扇形束）准直器和锥束准直器来获取单光子发射计算机断层扫描数据。这样做的动机是平行束（或扇形束）准直器可以提供足够的采样，而锥束准直器能够提供更高的光子计数。即使总计数增加，这种混合系统在图像噪声和伪影减少方面也没有显著改善（如果有的话）。如果使用传统的迭代最大似然期望最大化算法来重建图像，那么重建结果可能比仅使用平行束（或仅使用扇形束）系统差。本文使用奇异值分解（SVD）分析来解释这种现象。