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新的基于实验室的X射线定量相衬成像(QPI)技术，即近场相衬成像(NFPty)，非常适合于对生物组织等吸收较弱的分层样品进行多尺度成像。NFPty提供了通过其他实验室QPI技术获得的分辨率桥梁，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，其应用涵盖生命科学和物理科学。同步加速器是执行XI的最好工具；然而，它们的数量很少，使得访问具有竞争力，它可以进行基础科学研究，但不能用于日常应用。为了服务于更大的群体，从学术界到工业界，至关重要的是将同步加速器诞生的X射线成像技术转化为实验室来源，方法是开发出解决X射线束质量下降的方法。X射线相衬成像(XPCI)是X射线成像的一个子集，它允许对吸收性能相似的弱吸收样品和区分材料进行成像。有不同的实现方式：从最简单的同轴全息术到边缘照明、光栅干涉法、近场和远场光刻。这些成像工具在同步加速器设施中可用，其中一些工具，如边缘照明、光栅干涉测量，已成功地适用于实验室信号源。NFP TY尚未输出到实验室，但它是一个很有前途的候选产品：NFP TY需要简单的设置，放宽了x射线束质量要求，并受益于稳健的重建算法。该项目将NFP TY转换到实验室环境中，使其可供大型用户社区使用。该项目使用模拟和实验来使该方法适应较低的通量和实验室源的X射线质量，并开发了一种专用仪器。该项目将设在伦敦大学学院高级X射线成像小组内，该小组的活动重点是为实验室来源开发新的X射线成像技术。在伦敦大学学院，实验将使用不同的X射线源(从标准旋转阳极到新型液体金属喷射器)。为了最大限度地发挥项目的影响，这项研究将由脑成像案例研究驱动，最终目的是展示这项技术在这一重要领域的潜力。通过与该领域的专家(加的夫大学的Palombo博士、伦敦大学的Parker教授和罗马CNR-Nanotec的Fratini博士)密切合作，基于实验室的NFP将被应用于脑组织和脑模型的成像，并使用获得的数据来验证扩散磁共振成像(DMRI)。数字磁共振成像是脑研究和诊断的重要工具。然而，由于任务的多尺度性质，dMRI信号的解释和分析的有效性是具有挑战性的。验证依赖于来自体外样本、软件模体或物理模体的数据。身体幻影的优势是逼真和可控的，同时防止动物祭祀。然而，创建有用的大脑仿生模体需要在微米分辨率下准确地表征模体结构，并对细胞结构进行特定的对比。这些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，但对这些设施的有限访问限制了可用的统计数据。该项目将使使用NFP TY在标准实验室中获取这些数据成为可能。该方案将生产一种视野可调的新仪器，视野从100微米到毫米(神经元排列的尺度和典型的磁共振体素)，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理解大脑结构，指导更好的幻影的开发，并推动dMRI的验证。