Stayman J Webster, Tivnan Matthew, Gang Grace J, Wang Wenying, Shapira Nadav, Noël Peter B
Johns Hopkins University, Department of Biomedical Engineering, Baltimore, MD.
University of Pennsylvania, Department of Radiology, Philadelphia, PA.
Conf Proc Int Conf Image Form Xray Comput Tomogr. 2020 Aug;2020:630-633.
Interest in spectral CT for diagnostics and therapy evaluation has been growing. Acquisitions of data from distinct energy spectra provide, among other advantages, quantitative density estimations for multiple materials. We introduce a novel spectral CT concept that includes a fine-pitch grating for prefiltration of the x-ray beam. The attenuation behavior of this grating changes significantly if x-rays are slightly angled in relation to the grating structures. To apply such an angle (i.e. switch between the different filtrations) we propose a fast, controllable, and precise solution by moving the focal spot of the x-ray tube. In this work, we performed preliminary evaluations with a grating prototype on a CT test bench. Our results include x-ray spectrometer measurements that reveal diverse and controllable spectral shaping between 4° and 6° for a specific grating design. Additional experiments with a contrast agent phantom illustrated the capability to decompose clinically relevant iodine concentrations (5, 10, 20, and 50mg/mL) - demonstrating the feasibility of the grating-based approach. Ongoing and future studies will investigate the potential of this novel concept as a relatively simple upgrade to standard energy-integrating CT.
对光谱CT用于诊断和治疗评估的兴趣一直在增长。从不同能谱采集数据具有诸多优势，其中包括对多种物质进行定量密度估计。我们引入了一种新颖的光谱CT概念，该概念包括一个用于对X射线束进行预滤波的细间距光栅。如果X射线相对于光栅结构稍有角度，该光栅的衰减行为会发生显著变化。为了应用这样的角度（即在不同滤波之间切换），我们提出了一种通过移动X射线管焦点来实现快速、可控且精确的解决方案。在这项工作中，我们在CT试验台上使用光栅原型进行了初步评估。我们的结果包括X射线光谱仪测量，其显示了对于特定光栅设计在4°至6°之间多样且可控的光谱整形。使用造影剂模型的额外实验说明了分解临床相关碘浓度（5、10、20和50mg/mL）的能力——证明了基于光栅方法的可行性。正在进行的和未来的研究将探究这一新颖概念作为对标准能量积分CT相对简单升级的潜力。
