Near Field ptychography with a laboratory x-ray source: a new tool for brain tissue studies and beyond

使用实验室 X 射线源的近场叠层成像：脑组织研究及其他研究的新工具

• 批准号: EP/X020657/1
• 负责人: Silvia Cipiccia
• 金额: $ 34.24万
• 依托单位: University College London
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2023
• 资助国家: 英国
• 起止时间: 2023 至 无数据
• 项目状态: 未结题
• 来源: https://gtr.ukri.org/projects?ref=EP%2FX020657%2F1
• 关键词: Near; Field; ptychography; laboratory; ray

This project aims to develop a new, laboratory-based, x-ray quantitative phase contrast imaging (QPI) technique, namely near-field ptychography (NFPty), ideal for multi-scale imaging of weakly absorbing hierarchical samples, such as biological tissues. NFPty offers resolution bridging that available through other lab-based QPI techniques, and the high resolution of coherent diffraction imaging methods.X-ray imaging (XI) is a powerful tool for investigating matter non-destructively, with applications encompassing the life and physical sciences. Synchrotrons are the best instruments for performing XI; however, their small number makes access competitive, it enables fundamental science studies but not everyday applications. To serve a larger community, from academia to industry, it is essential to translate the x-ray imaging techniques born at synchrotrons to laboratory sources, by developing ways to work around the degraded quality of the x-ray beam. X-ray phase contrast imaging (XPCI) is a subset of x-ray imaging that allows imaging weakly absorbing specimens and differentiating materials with similar absorption properties. Different implementations exist: from the simplest in-line holography to edge illumination, grating interferometry, near and far-field ptychography. These imaging tools are available at synchrotron facilities and some of them, e.g. edge illumination, grating interferometry, have been successfully adapted to laboratory sources. NFPty has not yet been exported to laboratory but it is a promising candidate: NFPty requires a simple setup, has relaxed x-ray beam quality requirements, and benefits from robust reconstruction algorithms.This project will translate NFPty into the lab-environment to make it available to a large user community. The project uses simulations and experiments to adapt the method to the lower flux and x-ray quality of the laboratory sources and develop a dedicated instrument. The project will be based at UCL, within the Advanced X-ray Imaging Group whose activity is focused on developing new x-ray imaging techniques for laboratory sources. At UCL different x-ray sources (from standard rotating anode to the novel Liquid Metal Jet) will be available for the experiments.To maximise the impact of the project, the research will be driven by a case study in brain imaging, with the ultimate aim of demonstrating the technique's potential in that important area. By working closely with experts in the field (Dr Palombo from Cardiff University, Prof Parker from UCL and, Dr Fratini from CNR-Nanotec Rome), the lab-based NFPty will be applied to image brain tissue and brain phantoms and use the acquired data to validate diffusion Magnetic Resonance Imaging (dMRI). dMRI is a key tool for brain study and diagnosis. However, the interpretation of dMRI signal and the validation of the analysis are challenging because of the multiscale nature of the task. The validation relies on data from ex-vivo samples, software phantoms or physical phantom. Physical phantoms have the advantage of being realistic and controllable while preventing animal sacrifice. Nevertheless, the creation of useful brain biomimetic phantoms requires accurate characterization of the phantom structure at micrometric resolution and specific contrast for cellular structures. This information can be directly obtained by using multiscale high-resolution XPCI at synchrotrons, but the limited access to these facilities limits the available statistics. This project will make it possible to acquire these data in a standard laboratory by using NFPty. The programme will produce a new instrument with adjustable field of view from 100s of microns to millimetres (scale of the neuron's arrangements and typical MRI voxel), with sub-micron resolution (scale of the cellular/sub-cellular structures). The acquired data will be instrumental in understanding brain structure, guiding the development of better phantoms, and driving the validation of dMRI.

该项目旨在开发一种基于实验室的新型 X 射线定量相衬成像 (QPI) 技术，即近场叠层成像 (NFPty)，非常适合生物组织等弱吸收分层样品的多尺度成像。 NFPty 提供可通过其他基于实验室的 QPI 技术实现的分辨率桥接，以及相干衍射成像方法的高分辨率。X 射线成像 (XI) 是非破坏性研究物质的强大工具，其应用涵盖生命和物理科学。同步加速器是执行 XI 的最佳仪器；然而，它们的数量较少使得访问具有竞争力，它可以进行基础科学研究，但不能进行日常应用。为了服务于从学术界到工业界的更大社区，必须通过开发解决 X 射线束质量下降问题的方法，将同步加速器产生的 X 射线成像技术转化为实验室来源。 X 射线相衬成像 (XPCI) 是 X 射线成像的一个子集，可对弱吸收样本进行成像并区分具有相似吸收特性的材料。存在不同的实现方式：从最简单的在线全息术到边缘照明、光栅干涉测量法、近场和远场叠层照相术。这些成像工具可在同步加速器设施中使用，其中一些，例如边缘照明、光栅干涉测量法已成功应用于实验室光源。 NFPty 尚未导出到实验室，但它是一个有前途的候选者：NFPty 需要简单的设置，具有宽松的 X 射线束质量要求，并受益于强大的重建算法。该项目将把 NFPty 转化为实验室环境，使其成为现实可供大型用户社区使用。该项目通过模拟和实验使该方法适应实验室源的较低通量和 X 射线质量，并开发专用仪器。该项目将设在伦敦大学学院的高级 X 射线成像小组内，该小组的活动重点是为实验室源开发新的 X 射线成像技术。在伦敦大学学院，不同的 X 射线源（从标准旋转阳极到新颖的液态金属射流）将可用于实验。为了最大限度地发挥该项目的影响，该研究将通过脑成像案例研究来推动，最终目的是展示该技术在该重要领域的潜力。通过与该领域的专家（卡迪夫大学的 Palombo 博士、伦敦大学学院的 Parker 教授和罗马 CNR-Nanotec 的 Fratini 博士）密切合作，基于实验室的 NFPty 将应用于对脑组织和脑模型进行成像，并使用获取的数据验证扩散磁共振成像 (dMRI)。 dMRI 是大脑研究和诊断的关键工具。然而，由于任务的多尺度性质，dMRI 信号的解释和分析的验证具有挑战性。验证依赖于来自离体样本、软件模型或物理模型的数据。物理幻影的优点是真实、可控，同时可以防止动物牺牲。然而，创建有用的大脑仿生模型需要以微米分辨率和细胞结构的特定对比度准确表征模型结构。该信息可以通过在同步加速器上使用多尺度高分辨率 XPCI 直接获得，但对这些设施的访问有限限制了可用的统计数据。该项目将使得使用 NFPty 在标准实验室获取这些数据成为可能。该计划将生产一种新型仪器，其视野范围可从数百微米到毫米（神经元排列和典型 MRI 体素的尺度），具有亚微米分辨率（细胞/亚细胞结构的尺度）。获得的数据将有助于了解大脑结构、指导更好的模型的开发以及推动 dMRI 的验证。