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Dual-energy CT imaging over non-overlapping, orthogonal arcs of limited-angular ranges
Journal of X-Ray Science and Technology ( IF 3 ) Pub Date : 2021-09-23 , DOI: 10.3233/xst-210974
Buxin Chen 1 , Zheng Zhang 1 , Dan Xia 1 , Emil Y Sidky 1 , Xiaochuan Pan 1, 2
Affiliation  

BACKGROUND: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 andthe imaged subject. OBJECTIVE: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. METHODS: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. RESULTS: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 form 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. CONCLUSIONS: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.

中文翻译:

双能量 CT 成像在非重叠、有限角度范围的正交弧上

背景:人们对具有有限角度范围 (LAR) 扫描弧的双能计算机断层扫描 (DECT) 成像感兴趣,以减少扫描时间和辐射剂量,并使 C 臂 CT 的扫描配置能够避免可能的碰撞旋转 X 射线管/探测器和成像对象。目标:在这项工作中,我们研究了一种具有实际 DECT 兴趣的配置类型的图像重建,称为双正交弧配置,其中低和高 kVp 数据是在两个相等的非重叠弧上收集的LAR α,范围从 30°到 90°,间隔 90°。该配置可以很容易地实现,例如,在具有 90° 分隔的双源或使用慢速 kVp 开关技术的 CT 上。方法:先前为传统单能量 CT 中的图像重建开发的方向全变差 (DTV) 算法经过定制,可在具有双正交弧配置的 DECT 中实现图像重建。结果: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 算法的单色图像显着减少了 LAR 伪影,这在现有算法中观察到了,因此就度量 PCC 和 nMI 而言,它们与从全角度范围数据获得的参考图像在视觉上相当好地相关。此外,根据具有双正交弧配置的 DECT LAR 数据估计的有效原子序数具有合理的一致性,相对误差高达 ∼ 10%,与从 DECT 中的全角度范围数据估计的那些。结论:工作中获得的结果可能对诊断 CT 或 C 臂 CT 成像中实际双能应用相关的 LAR 配置的设计产生见解。
更新日期:2021-09-24
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