Study of OSEM with different subsets in grating-based X-ray differential phase-contrast imaging
Study of OSEM with different subsets in grating-based X-ray differential phase-contrast imaging
复制标题
光栅X射线微分相衬成像中不同子集的OSEM研究
DOI：
10.1007/s00216-011-5080-6
复制
发表时间：
2011-08-01
影响因子：
4.3
通讯作者：
Wu, Ziyu
中科院分区：
文献类型：
--
作者：
Zhang, Kai;Hong, Youli;Wu, Ziyu
X射线成像令人印象深刻的发展与基于光栅干涉的X射线相衬计算机层析成像相关，与传统的基于吸收的成像相比，这项技术提供了更高的对比度。最近提出了一种新的“一步法”，能够将相位信息从其他贡献中分离出来。这种方法不仅简化了数据采集程序，而且与现有的分阶段方法相比，显著减少了提供给样品的剂量。然而，图像重建过程比传统方法要求更高，必须开发新的算法来利用“一步法”的优势。在本文所讨论的工作中，一种称为有序子集期望最大化的快速迭代图像重建方法被应用于实验数据以评估其性能和适用范围。比较了不同子集的OEM算法的重建图像质量和收敛速度。计算机模拟和实验结果证实了这种新算法在相衬CT应用中的可靠性。与传统的滤波反投影算法相比，特别是在存在噪声采集的情况下，它在更高的空间分辨率和更低的噪声下提供了更好的图像。我们强调，该方法与未来的X射线相衬成像临床应用高度兼容。
Impressive developments in X-ray imaging are associated with X-ray phase contrast computed tomography based on grating interferometry, a technique that provides increased contrast compared with conventional absorption-based imaging. A new "single-step" method capable of separating phase information from other contributions has been recently proposed. This approach not only simplifies data-acquisition procedures, but, compared with the existing phase step approach, significantly reduces the dose delivered to a sample. However, the image reconstruction procedure is more demanding than for traditional methods and new algorithms have to be developed to take advantage of the "single-step" method. In the work discussed in this paper, a fast iterative image reconstruction method named OSEM (ordered subsets expectation maximization) was applied to experimental data to evaluate its performance and range of applicability. The OSEM algorithm with different subsets was also characterized by comparison of reconstruction image quality and convergence speed. Computer simulations and experimental results confirm the reliability of this new algorithm for phase-contrast computed tomography applications. Compared with the traditional filtered back projection algorithm, in particular in the presence of a noisy acquisition, it furnishes better images at a higher spatial resolution and with lower noise. We emphasize that the method is highly compatible with future X-ray phase contrast imaging clinical applications.