Dynamic Colour X-ray Computed Tomography Imaging

x射线计算机断层成像是一种广泛使用的技术，已应用于许多不同的应用；从大型设施的基础材料科学到医院的医学诊断。CT成像是通过测量样品在不同角度的透射x射线，然后通过计算重建单个2D切片，以在特定时间点产生完整的3D密度对比图像来进行的。这种传统的CT成像只是测量在给定时间通过样品中某一点的透射x射线的强度，而不测量x射线颜色（能量）中包含的潜在重要化学信息。在时间分辨彩色计算机断层扫描（5D-CT）中，除了标准的时间和空间信息外，还记录了每个x射线相互作用的能量。这种颜色信息的测量通过提供样品化学性质的同步成像以及其结构的时间分辨3D成像来增强现有技术。实现这种成像能力的最大挑战是高帧率、能量分辨率和x射线成像技术的可用性。作为英国国家实验室x射线计算机断层扫描（NXCT）研究机构的一部分，曼彻斯特大学是问题持有人。NXCT的主要目标之一是为英国的研究人员提供最先进的x射线仪器和研究专业知识，使设计和实施复杂的实验成为可能。曼彻斯特大学已经确定彩色x射线CT是一项具有重要战略意义的技术，并获得了EPSRC的资助，以开拓其发展。动态彩色x射线计算机断层成像技术的交付将提供一种变革性的能力，这将有利于广泛的学科。最初的目标应用领域包括：研究纳米材料在催化[1]中的作用，观察共晶合金[2]中的枝晶生长，表征新型电池[3]的充放电特性以及重元素污渍在生物组织中的扩散[4]。STFC是解决方案提供商，十多年来一直致力于开发彩色x射线成像相机。他们现有系统的帧率目前限制了彩色x射线成像的时间分辨率和光子通量。STFC最近开发了一种新的HEXITEC-MHz专用集成电路，它以1 MHz的连续帧速率工作，使彩色成像能够在ct相关通量为bb10 ^6光子s-1 mm-2的情况下进行。在这个项目中，STFC将向曼彻斯特大学提供世界上第一个可部署的这种类型的探测器，曼彻斯特大学将对系统的成像性能进行表征，并为这些新颖的5D数据集开发重建算法，推动这项技术迅速发展到可以使许多研究人员受益的状态，解决许多通过NXCT访问路由启用的重要应用比尔等人，菲尔。反式。r . Soc。A.3762017005720170057 http://doi.org/10.1098/rsta.2017.0057[2]冯等，材料学报，221,2021,117389,https://doi.org/10.1016/j.actamat.2021.117389[3]结晶的。(2020)。33,1434 -1443, https://doi.org/10.1107/S1600576720012078[4] Jayarantha等人，IEEE Access, vol. 9, pp. 49912- 49919,2021, https://doi.org/10.1109/ACCESS.2021.3069368 [5] M. Veale等人，同步辐射新闻，31:6,28-32,https://doi.org/10.1080/08940886.2018.1528431

X-ray Computed Tomography imaging is a widely used technique that has been applied across many different applications; from fundamental materials science at large facilities to medical diagnosis in hospitals. CT imaging is carried out by measuring transmitted X-rays at a variety of angles through a sample and then computationally reconstructing individual 2D slices to produce a full 3D density contrast image at a particular point in time. This traditional CT imaging simply measures the intensity of transmitted X-rays through a point in a sample at a given time, potentially-significant chemical information contained within the colour (energy) of the X-rays isn't measured. In time-resolved colour Computed Tomography, 5D-CT, the energy of each X-ray interaction is recorded in addition to the standard temporal and spatial information. The measurement of this colour information enhances existing techniques by providing simultaneous imaging of the chemical nature of a sample in addition to the time-resolved 3D imaging of its structure. The biggest challenge to realising this imaging capability has been the availability of high frame rate, energy resolving, X-ray imaging technologies.Working as part of the UK's National Research Facility for lab-based X-ray Computed Tomography (NXCT), the University of Manchester are the problem holder. One of the key aims of the NXCT is to provide access for researchers in the UK to state-of-the-art X-ray instruments and the research expertise that enables the design and implementation of complex experiments. The University of Manchester have already identified colour X-ray CT as a strategically important technique and have received funding from EPSRC to pioneer its development. The delivery of a Dynamic Colour X-ray Computed Tomography imaging technology would provide a transformative capability which would benefit a broad range of disciplines. Initial target application areas include, the study of the role of nanomaterials in catalysis [1], observing the dendritic growth in eutectic alloys [2], characterising the charging-discharging of novel battery types [3] and the diffusion of heavy element stains through biological tissue [4]. STFC, the solution provider, have been developing colour X-ray imaging cameras for over a decade [5]. The frame rate of their existing systems currently limit both the temporal resolution and photon fluxes at which colour X-ray imaging can be applied. STFC have recently developed a new HEXITEC-MHz ASIC which operates at a continuous frame rate of 1 MHz enabling colour imaging to be carried out at CT-relevant fluxes of >10^6 photons s-1 mm-2. In this project STFC will deliver the world's first deployable detector of this type to the University of Manchester who will characterise the imaging performance of the system and develop the reconstruction algorithms for these novel 5D data sets pushing this technology quickly to a state where it can benefit many researchers addressing many important applications enabled through the NXCT access routes.[1] Beale et al, Phil. Trans. R. Soc. A.3762017005720170057 http://doi.org/10.1098/rsta.2017.0057[2] Feng et al, Acta Materialia, 221, 2021, 117389, https://doi.org/10.1016/j.actamat.2021.117389[3] Connolley et al, J. Appl. Cryst. (2020). 53, 1434-1443, https://doi.org/10.1107/S1600576720012078[4] Jayarantha et al, IEEE Access, vol. 9, pp. 49912-49919, 2021, https://doi.org/10.1109/ACCESS.2021.3069368 [5] M. Veale et al, Synchrotron Radiation News, 31:6, 28-32, https://doi.org/10.1080/08940886.2018.1528431