Shimao Daisuke, Kunisada Toshiyuki, Sugiyama Hiroshi, Ando Masami
Department of Radiological Sciences, Ibaraki Prefectural University of Health Sciences, Ami 4669-2, Ami-machi, Inashiki-gun, Ibaraki 300-0394, Japan.
Eur J Radiol. 2008 Dec;68(3 Suppl):S27-31. doi: 10.1016/j.ejrad.2008.04.037. Epub 2008 Jul 2.
A tomogram of a finger joint showing articular cartilage was generated based on X-ray dark-field imaging (XDFI) using the shift-and-add tomosynthesis algorithm. The experiment was performed at beamline 14B of the Photon Factory in Tsukuba, Japan, using synchrotron X-rays from a vertical wiggler. The incident X-ray energy was 36.0 keV. The X-ray optics for XDFI comprised two Si crystals: an asymmetric cut Si (220) monochromator-collimator and a 1.1-mm thick Si (220) Laue-case analyzer. The object was an intact cadaveric proximal interphalangeal joint fixed in formalin. Raw projection data were acquired by XDFI in a total of 41 views through an angle of 20 degrees in 0.5 degrees increments. The object and detector were synchronously rotated such that the fulcrum plane in the object and detector plane remained parallel. The X-ray dose for one piece of raw projection data was set to one-eleventh of that for one standard projection image by XDFI. Eleven views through an angle of 10 degrees in increments of 1 degrees of all 41 appropriately shifted raw projection data were added to produce arbitrary tomograms parallel to the fulcrum plane. We obtained a clear tomogram of the finger joint including the articular cartilage with the moderate artifact peculiar to tomosynthesis. Consequently, arbitrary tomograms can be obtained for the same X-ray dose as that received for one standard projection image by XDFI. The fact that an inner structure such as articular cartilage, which is invisible to conventional X-ray imaging methods, has been visualized on a tomogram with preserved refraction-enhanced contrast, is of considerable significance to clinical medicine.
基于移位相加断层合成算法，利用X射线暗场成像（XDFI）生成了一张显示关节软骨的手指关节断层图像。该实验在日本筑波光子工厂的14B光束线进行，使用来自垂直摆动器的同步加速器X射线。入射X射线能量为36.0 keV。用于XDFI的X射线光学器件包括两块硅晶体：一块非对称切割的硅（220）单色仪 - 准直仪和一块1.1毫米厚的硅（220）劳厄盒分析仪。样本为固定在福尔马林中的完整尸体近端指间关节。原始投影数据通过XDFI在总共41个视图中采集，角度范围为20度，以0.5度为增量。样本和探测器同步旋转，使得样本平面和探测器平面中的支点平面保持平行。通过XDFI，将一条原始投影数据的X射线剂量设置为一张标准投影图像剂量的十一分之一。将41条适当移位的原始投影数据中以1度为增量、角度范围为10度的11个视图相加，以生成与支点平面平行的任意断层图像。我们获得了一张清晰的手指关节断层图像，包括关节软骨，同时带有断层合成特有的适度伪影。因此，对于相同的X射线剂量，通过XDFI可以获得与一张标准投影图像相同剂量下的任意断层图像。关节软骨等传统X射线成像方法无法看到的内部结构，在保留折射增强对比度的断层图像上得以可视化，这一事实对临床医学具有相当重要的意义。
