Dual-energy CT imaging over non-overlapping, orthogonal arcs of limited-angular ranges.
Dual-energy CT imaging over non-overlapping, orthogonal arcs of limited-angular ranges.
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DOI：
10.3233/xst-210974
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发表时间：
2021
影响因子：
3
通讯作者：
Pan X
中科院分区：
文献类型：
--
作者：
Chen B;Zhang Z;Xia D;Sidky EY;Pan X
感兴趣的是具有有限角度范围（LAR）的扫描弧的双能量计算机断层摄影（DECT）成像，用于减少扫描时间和辐射剂量，并且用于实现可以避免旋转X射线管/探测器与成像对象之间的可能碰撞的C形臂CT的扫描配置。在这项工作中，我们研究了一种实际DECT感兴趣的配置类型的图像重建，称为两个正交弧配置，其中低和高kVp数据收集在两个不重叠的弧相等LAR α，范围从30°到90°，分开90°。可以容易地实现该配置，例如，在CT上使用90°分开的双源或使用慢kVp开关技术。先前开发的用于常规单能量CT中的图像重建的方向全变分（DTV）算法被定制为使得能够在具有两个正交弧配置的DECT中进行图像重建。对获得的单色图像和估计的有效原子序数进行目视检查和定量分析，我们观察到，来自LAR数据的DTV算法的单色图像具有大幅减少的LAR伪影，这在现有算法的那些中以其他方式观察到，并且因此在度量PCC和nMI方面与从全角度范围数据获得的其参考图像在视觉上相当好地相关。此外，用双正交弧位形的DECT的LAR数据估算的有效原子序数与用DECT的全角度范围数据估算的有效原子序数吻合较好，相对误差可达~10%.在工作中获得的结果可能会产生洞察到实际的双能量应用相关的诊断CT或C形臂CT成像的LAR配置的设计。
Interest exists in dual-energy computed tomography (DECT) imaging with scanning arcs of limited-angular ranges (LARs) for reducing scan time and radiation dose, and for enabling scan configurations of C-arm CT that can avoid possible collision between the rotating X-ray tube/detector and the imaged subject. In this work, we investigate image reconstruction for a type of configurations of practical DECT interest, referred to as the two-orthogonal-arc configuration, in which low- and high-kVp data are collected over two non-overlapping arcs of equal LAR α, ranging from 30° to 90°, separated by 90°. The configuration can readily be implemented, e.g., on CT with dual sources separated by 90° or with the slow-kVp-switching technique. The directional-total-variation (DTV) algorithm developed previously for image reconstruction in conventional, single-energy CT is tailored to enable image reconstruction in DECT with two-orthogonal-arc configurations. Performing visual inspection and quantitative analysis of monochromatic images obtained and effective atomic numbers estimated, we observe that the monochromatic images of the DTV algorithm from LAR data are with substantially reduced LAR artifacts, which are observed otherwise in those of existing algorithms, and thus visually correlate reasonably well, in terms of metrics PCC and nMI, with their reference images obtained from full-angular-range data. In addition, effective atomic numbers estimated from LAR data of DECT with two-orthogonal-arc configurations are in reasonable agreement, with relative errors up to ~10% , with those estimated from full-angular-range data in DECT. The results acquired in the work may yield insights into the design of LAR configurations of practical dual-energy application relevance in diagnostic CT or C-arm CT imaging.