A grating-based single-shot x-ray phase contrast and diffraction method for in vivo imaging
A grating-based single-shot x-ray phase contrast and diffraction method for in vivo imaging
复制标题
DOI：
10.1118/1.3501311
复制
发表时间：
2010-11-01
期刊：
影响因子：
3.8
通讯作者：
Wen, Han
中科院分区：
文献类型：
--
作者：
Bennett, Eric E.;Kopace, Rael;Wen, Han
目的：本研究的目的是开发一种基于光栅的相位衬度X射线成像方法的单次激发版本，并证明其在体内动物成像的能力。文中介绍了该方法的原理和实验结果。它们显示了相位对比信号中伪影的来源以及最小化伪影的最佳设计。他们还讨论了其目前的局限性和方法来克服themes.Methods：一个单一的铅网格之间插入一个X射线管和X射线相机在平面摄影设置的中途。该光栅作为透射光栅，在相机上投射周期性的暗条纹。相机具有足够的空间分辨率来分辨条纹。折射和衍射在成像物体中分别表现为条纹的位置偏移和幅度衰减。为了精确地量化这些变化，而不强加一个固定的几何关系之间的相机像素阵列和条纹，空间谐波方法在傅立叶域的开发。微分相位（折射）对比度的水平作为硬件规格和设备的几何形状的函数推导出来，并用于指导网格和对象的最佳位置。收集啮齿动物四肢的离体和体内图像以证明该方法的能力。使用50 W管的曝光时间为28 s。结果：微分相衬图像的玻璃珠收购在不同的网格和对象的位置证实了理论预测的相衬度和外来文物如何随设备的几何形状。在麻醉大鼠，一个单一的曝光产生的吸收，微分相差和衍射的伪像。微分相位差是最强的骨软组织接口，而衍射是最强的bone.Conclusions：空间谐波方法使我们能够获得吸收，微分相位差，衍射图像，所有从一个单一的原始图像，是可行的活动物。由于该方法的灵敏度与光栅的密度成正比，因此定制的微加工光栅应该上级现成的铅栅。[DOI 10.1118/1.3501311]
Purpose: The purpose of this study is to develop a single-shot version of the grating-based phase contrast x-ray imaging method and demonstrate its capability of in vivo animal imaging. Here, the authors describe the principle and experimental results. They show the source of artifacts in the phase contrast signal and optimal designs that minimize them. They also discuss its current limitations and ways to overcome them.Methods: A single lead grid was inserted midway between an x-ray tube and an x-ray camera in the planar radiography setting. The grid acted as a transmission grating and cast periodic dark fringes on the camera. The camera had sufficient spatial resolution to resolve the fringes. Refraction and diffraction in the imaged object manifested as position shifts and amplitude attenuation of the fringes, respectively. In order to quantify these changes precisely without imposing a fixed geometric relationship between the camera pixel array and the fringes, a spatial harmonic method in the Fourier domain was developed. The level of the differential phase (refraction) contrast as a function of hardware specifications and device geometry was derived and used to guide the optimal placement of the grid and object. Both ex vivo and in vivo images of rodent extremities were collected to demonstrate the capability of the method. The exposure time using a 50 W tube was 28 s.Results: Differential phase contrast images of glass beads acquired at various grid and object positions confirmed theoretical predictions of how phase contrast and extraneous artifacts vary with the device geometry. In anesthetized rats, a single exposure yielded artifact-free images of absorption, differential phase contrast, and diffraction. Differential phase contrast was strongest at bone-soft tissue interfaces, while diffraction was strongest in bone.Conclusions: The spatial harmonic method allowed us to obtain absorption, differential phase contrast, and diffraction images, all from a single raw image and is feasible in live animals. Because the sensitivity of the method scales with the density of the gratings, custom microfabricated gratings should be superior to off-the-shelf lead grids. [DOI: 10.1118/1.3501311]