Wang Ge, Cong Wenxiang, Shen Haiou, Zou Yu
SBES Division/ICTAS Center for Biomedical Imaging, VT-WFU School of Biomedical Engineering, Virginia Tech, Blacksburg, VA 24061, USA.
Int J Biomed Imaging. 2009;2009:847537. doi: 10.1155/2009/847537. Epub 2010 Feb 16.
Although x-ray imaging is widely used in biomedical applications, biological soft tissues have small density changes, leading to low contrast resolution for attenuation-based x-ray imaging. Over the past years, x-ray small-angle scattering was studied as a new contrast mechanism to enhance subtle structural variation within the soft tissue. In this paper, we present a detection method to extract this type of x-ray scattering data, which are also referred to as dark-field signals. The key idea is to acquire an x-ray projection multiple times with varying collimation before an x-ray detector array. The projection data acquired with a collimator of a sufficiently high collimation aspect ratio contain mainly the primary beam with little scattering, while the data acquired with an appropriately reduced collimation aspect ratio include both the primary beam and small-angle scattering signals. Then, analysis of these corresponding datasets will produce desirable dark-field signals; for example, via digitally subtraction. In the numerical experiments, the feasibility of our dark-field detection technology is demonstrated in Monte Carlo simulation. The results show that the acquired dark field signals can clearly reveal the structural information of tissues in terms of Rayleigh scattering characteristics.
尽管X射线成像在生物医学应用中被广泛使用，但生物软组织的密度变化很小，导致基于衰减的X射线成像的对比度分辨率较低。在过去的几年里，X射线小角散射作为一种新的对比度机制被研究，以增强软组织内的细微结构变化。在本文中，我们提出了一种检测方法来提取这类X射线散射数据，这些数据也被称为暗场信号。关键思想是在X射线探测器阵列之前，通过改变准直度多次获取X射线投影。用具有足够高准直纵横比的准直器获取的投影数据主要包含散射很少的主光束，而用适当降低的准直纵横比获取的数据则包括主光束和小角散射信号。然后，对这些相应的数据集进行分析将产生理想的暗场信号；例如，通过数字减法。在数值实验中，我们的暗场检测技术的可行性在蒙特卡罗模拟中得到了证明。结果表明，所获取的暗场信号能够根据瑞利散射特性清晰地揭示组织的结构信息。
