Design of iterative ROI transmission tomography reconstruction procedures and image quality analysis.
Design of iterative ROI transmission tomography reconstruction procedures and image quality analysis.
复制标题
迭代 ROI 透射断层扫描重建程序和图像质量分析的设计。
DOI：
--
复制
发表时间：
2010
期刊：
影响因子：
--
通讯作者：
G. Soulez
中科院分区：
文献类型：
--
作者：
B. Hamelin;Y. Goussard;J. Dussault;G. Cloutier;G. Beaudoin;G. Soulez
目的
研究了一种用于小视场区域高分辨率成像的边缘保持迭代CT重建算法。它属于感兴趣区域重建技术家族，其中首先执行整个视场的低成本导频重建，然后用于推导感兴趣区域对投影数据的贡献。这些投影用于使用正则化迭代算法的感兴趣区域（ROI）的高分辨率重建，从而显著节省计算。本文探讨了如何获得飞行员重建的全视场的技术影响总的运行时间和图像质量的兴趣区域。
方法
以前的文献贡献都集中在一个单一的方法进行试点重建。在本文中，两个这样的方法进行了比较：滤波反投影和低分辨率正则化迭代重建方法。ROI重建在图像质量和计算成本方面与模拟和物理体模（Catphan 600）研究进行了比较，以评估对ROI重建质量影响最大的折衷方案。
结果
对于模拟体模，ROI图像中出现的新伪影是由导频重建中的显著误差引起的。这些误差包括试验图像网格的过度粗糙和射束硬化伪影。使用Catphan 600体模时，扫描仪成像模型和迭代重建算法成像模型的差异会导致ROI图像中出现暗边界伪影。
结论
廉价的导频重建技术（分析算法，非常粗糙的网格惩罚似然）是在许多常见情况下的实际选择。然而，它们可能产生由边缘退化或射束硬化改变的背景图像，从而在用于ROI重建的数据中引起投影不一致。因此，ROI图像具有显著的条纹和斑点伪影，这不利地影响分辨率与噪声的折衷。在这些情况下，边缘保持惩罚似然方法不太粗糙的图像网格证明是更强大的，并提供最佳的ROI图像质量。
PURPOSE
An iterative edge-preserving CT reconstruction algorithm for high-resolution imaging of small regions of the field of view is investigated. It belongs to a family of region-of-interest reconstruction techniques in which a low-cost pilot reconstruction of the whole field of view is first performed and then used to deduce the contribution of the region of interest to the projection data. These projections are used for a high-resolution reconstruction of the region of interest (ROI) using a regularized iterative algorithm, resulting in significant computational savings. This paper examines how the technique by which the pilot reconstruction of the full field of view is obtained affects the total runtime and the image quality in the region of interest.
METHODS
Previous contributions to the literature have each focused on a single approach for the pilot reconstruction. In this paper, two such approaches are compared: the filtered backprojection and a low-resolution regularized iterative reconstruction method. ROI reconstructions are compared in terms of image quality and computational cost over simulated and physical phantom (Catphan600) studies, in order to assess the compromises that most impact the quality of the ROI reconstruction.
RESULTS
With the simulated phantom, new artifacts that appear in the ROI images are caused by significant errors in the pilot reconstruction. These errors include excessive coarseness of the pilot image grid and beam-hardening artifacts. With the Catphan600 phantom, differences in the imaging model of the scanner and that of the iterative reconstruction algorithm cause dark border artifacts in the ROI images.
CONCLUSIONS
Inexpensive pilot reconstruction techniques (analytical algorithms, very-coarse-grid penalized likelihood) are practical choices in many common cases. However, they may yield background images altered by edge degradation or beam hardening, inducing projection inconsistency in the data used for ROI reconstruction. The ROI images thus have significant streak and speckle artifacts, which adversely affect the resolution-to-noise compromise. In these cases, edge-preserving penalized-likelihood methods on not-too-coarse image grids prove to be more robust and provide the best ROI image quality.