School of Integrated Technology, 205 Science Engineering and Pharmacy Hall, Yonsei University, 406-840 Incheon, Korea.
Phys Med Biol. 2014 Mar 7;59(5):1189-202. doi: 10.1088/0031-9155/59/5/1189. Epub 2014 Feb 20.
We present initial experimental results of a rotating-gantry multi-source inverse-geometry CT (MS-IGCT) system. The MS-IGCT system was built with a single module of 2 × 4 x-ray sources and a 2D detector array. It produced a 75 mm in-plane field-of-view (FOV) with 160 mm axial coverage in a single gantry rotation. To evaluate system performance, a 2.5 inch diameter uniform PMMA cylinder phantom, a 200 µm diameter tungsten wire, and a euthanized rat were scanned. Each scan acquired 125 views per source and the gantry rotation time was 1 s per revolution. Geometric calibration was performed using a bead phantom. The scanning parameters were 80 kVp, 125 mA, and 5.4 µs pulse per source location per view. A data normalization technique was applied to the acquired projection data, and beam hardening and spectral nonlinearities of each detector channel were corrected. For image reconstruction, the projection data of each source row were rebinned into a full cone beam data set, and the FDK algorithm was used. The reconstructed volumes from upper and lower source rows shared an overlap volume which was combined in image space. The images of the uniform PMMA cylinder phantom showed good uniformity and no apparent artifacts. The measured in-plane MTF showed 13 lp cm(-1) at 10% cutoff, in good agreement with expectations. The rat data were also reconstructed reliably. The initial experimental results from this rotating-gantry MS-IGCT system demonstrated its ability to image a complex anatomical object without any significant image artifacts and to achieve high image resolution and large axial coverage in a single gantry rotation.
我们展示了一种旋转机架多源逆几何 CT（MS-IGCT）系统的初步实验结果。MS-IGCT 系统由一个 2×4 个 X 射线源和一个 2D 探测器阵列的单个模块构建而成。它在单个机架旋转中产生了 75mm 的面内视场（FOV）和 160mm 的轴向覆盖范围。为了评估系统性能，我们扫描了一个 2.5 英寸直径的均匀 PMMA 圆柱体、一个 200µm 直径的钨丝和一只安乐死的大鼠。每个扫描从每个源获取 125 个视图，机架旋转时间为每转 1 秒。使用珠状模体进行几何校准。扫描参数为 80kVp、125mA 和每个源位置每视图 5.4µs 脉冲。对采集的投影数据应用了数据归一化技术，并校正了每个探测器通道的束硬化和谱非线性。对于图像重建，将每个源行的投影数据重新组合成一个全锥束数据集，并使用 FDK 算法。来自上源行和下源行的重建体积共享一个重叠体积，该重叠体积在图像空间中组合。均匀 PMMA 圆柱体的图像显示出良好的均匀性，没有明显的伪影。测量的面内调制传递函数（MTF）在 10%截止时显示出 13lp cm(-1)，与预期值非常吻合。大鼠数据也可靠地重建。该旋转机架 MS-IGCT 系统的初步实验结果表明，它能够在没有任何明显图像伪影的情况下对复杂解剖物体进行成像，并在单个机架旋转中实现高图像分辨率和大轴向覆盖范围。
