X-ray Phase-Contrast Imaging Using Near-Field Speckles - read free eBook in online reader or directly download on the web page. Select files or add your book in reader. Download and read online ebook X-ray Phase-Contrast Imaging Using Near-Field Speckles write by Marie-Christine Zdora. This book was released on 2021-02-16. X-ray Phase-Contrast Imaging Using Near-Field Speckles available in PDF, EPUB and Kindle. This thesis presents research on novel X-ray imaging methods that improve the study of specimens with small density differences, revealing their inner structure and density distribution. Exploiting the phase shift of X-rays in a material can significantly increase the image contrast compared to conventional absorption imaging. This thesis provides a practical guide to X-ray phase-contrast imaging with a strong focus on X-ray speckle-based imaging, the most recently developed phase-sensitive method. X-ray speckle-based imaging only requires a piece of abrasive paper in addition to the standard X-ray imaging setup. Its simplicity and robustness combined with the compatibility with laboratory X-ray sources, make it an ideal candidate for wide user uptake in a range of fields. An in-depth overview of the state of the art of X-ray speckle-based imaging and its latest developments is given in this thesis. It, furthermore, explores a broad range of applications, from X-ray optics characterisation, to biomedical imaging for 3D virtual histology and geological studies of volcanic rocks, demonstrating is promising potential. Moreover, the speckle-based technique is placed in the context of other phase-sensitive X-ray imaging methods to assist in the choice of a suitable method, hence serving as a guide and reference work for future users.
Phase-Contrast and Dark-Field Imaging
Phase-Contrast and Dark-Field Imaging - read free eBook in online reader or directly download on the web page. Select files or add your book in reader. Download and read online ebook Phase-Contrast and Dark-Field Imaging write by Simon Zabler. This book was released on 2019-01-08. Phase-Contrast and Dark-Field Imaging available in PDF, EPUB and Kindle. This book is a printed edition of the Special Issue "Phase-Contrast and Dark-Field Imaging" that was published in J. Imaging
Studies in X-ray Dynamic Speckle Imaging
Studies in X-ray Dynamic Speckle Imaging - read free eBook in online reader or directly download on the web page. Select files or add your book in reader. Download and read online ebook Studies in X-ray Dynamic Speckle Imaging write by Sarah Catherine Irvine. This book was released on 2010. Studies in X-ray Dynamic Speckle Imaging available in PDF, EPUB and Kindle. This thesis describes the study of two dynamic speckle systems present in the context of X-ray propagation-based phase contrast imaging. The first application to be examined is that of the rotating random phase screen diffuser, used in phase contrast imaging in order to improve the homogeneity of the sample-incident beam and thus ideally the image quality. The second pertains to the technique of flow measurement from analysis of blood speckle patterns. Whilst speckle is central to both of these, it is in quite different ways: a moving diffuser introduces a temporallyuncorrelated dynamic speckle pattern, the observed effect of which is an incoherently averaged smooth background intensity. Conversely, the time-dependent correlation of dynamic blood speckle patterns is deliberately exploited as a useful tool for the quantitative determination of flow. In the first instance we present the spatial coherence measurements of the biomedical imaging beamline BL20XU at SPring8, Japan, using a simple, low-cost prism based interferometry method developed by Suzuki (2004). We then study the effect of the addition of a rotating diffuser to the setup. Besides the observed increase in beam-homogeneity due to the diffuser, we show that the diffuser acts to decrease the observed degree of coherence as a fixed percentage of that measured in its absence. We are able to reproduce this effect in simulation via the model of the diffuser as the time-averaged incoherent sum of speckled intensities caused by random phaseperturbations to the X-ray wavefield. Following this key result, we extend our investigationof diffusers to study their effect on the quality of typical propagation-based phase contrast images, which depend on the high contrast and visibility of Fresnel diffraction fringe features. The deleterious effect of the diffuser on these fringes is demonstrated to be minimisable through the simple expedient of placing the diffuser as close as possible to the effective source of the beamline. This is explained through a discussion of local transverse phase gradients. In the second application which comprises the majority of this thesis, we begin with a characterising study of the speckle patterns observed in propagation-based X-ray phase contrast images of blood, a phenomenon insufficiently explained in the literature of the time. We adopt a theoretical model which allows us to view blood as a two-material system of randomly positioned red blood cells suspended within a plasma matrix, the projection of which effectively creates a weak random phase perturbation of the X-ray wavefield. Free-space propagation and associated self-interference of this wavefield yields phase contrast in the form of speckle. Its statistical analysis is demonstrated possible through inspection of the magnitude of the Fourier transform of the intensity. The Fourier description of the speckle is well characterised via application of the linear phase Contrast Transfer Function (CTF) formalism for weak objects in the Fresnel regime. The agreement between experiment, simulation and analytical expression is strong, providing an improved understanding of the speckle which may be applied to the velocimetric analysis of dynamic patterns. In view of the ultimate goal of achieving a high-resolution, accurate blood flow measurement technique capable of full-field multi-component vector analysis for in vivo cardiovascular research, we apply our knowledge of the speckle system to recommend key steps for future analysis of dynamic speckle patterns. We find it necessary to use single-image phase retrieval methods, specifically one based on the transport of intensity equation. For images recorded with typical levels of noise, the TIE-based phase retrieval algorithm requires significant regularisation due to the very low contribution of absorption to the final contrast. We also demonstrate the utility of Fourier mask filters for suppression of unwanted image artefacts. With the flow signal thus optimised, we develop methods for flow reconstruction based on the Abel transform. For a rotationally-symmetric flow, we present the first tomographic reconstructions of axial blood flow within a cylinder; after which we extend the validity of the reconstruction theory to include non-axial flow, culminating in the full, four-dimensional reconstruction of pulsatile flow within a simple in vitro stenotic model. Importantly, this new vector tomographic reconstruction technique may be achieved with single image pairs, which is important for non-steady flow patterns.
Multi-scale 3D Virtual Histology Via Phase-contrast X-ray Tomography with Synchrotron Radiation
Multi-scale 3D Virtual Histology Via Phase-contrast X-ray Tomography with Synchrotron Radiation - read free eBook in online reader or directly download on the web page. Select files or add your book in reader. Download and read online ebook Multi-scale 3D Virtual Histology Via Phase-contrast X-ray Tomography with Synchrotron Radiation write by Jasper Frohn. This book was released on 2023. Multi-scale 3D Virtual Histology Via Phase-contrast X-ray Tomography with Synchrotron Radiation available in PDF, EPUB and Kindle. To this day, the standard method for investigating biological tissue with cellular resolution is the examination under a light microscope, first denoted as histology by Karl Meyer in 1819. Despite the enormous success and importance of histology, it has two major disadvantages. Firstly, the specimen must be physically cut into thin sections due to the limited penetrating power of optical light, and secondly, additional staining of the specimen is required to achieve sufficient image contrast. Both disadvantages can be overcome by the non-destructive method of propagation-based X-ray phase-contrast tomography. While the mechanism of phase-contrast provides sufficient image contrast to image single cells, a tomographic imaging scheme with penetrating X-rays allows for an undamaged sample by virtually slicing the reconstructed 3D sample volume. In this work, the holotomography setup of the synchrotron endstation „GINIX“ (The Göttingen Instrument for Nanoscale-Imaging with X-Rays) was extended to a multi-scale X-ray phase-contrast tomography setup suitable for 3D virtual histology by adding two acquisition schemes. Compared to the existing setup, the first additional scheme is a propagation-based microtomography setup, which enlarges the reconstructed 3D volumes by a factor of approx. 64 at a fraction of the acquisition time (ca. 2 min). The second additional scheme aims for higher resolutions. To this end, the X-ray waveguide illumination was combined with photon counting detector with a large field of view and a novel phase reconstruction scheme, which is based on iterative farfield phase retrieval without an „empty-beam correction“ in the detector plane.
X-Ray Phase Contrast Imaging
X-Ray Phase Contrast Imaging - read free eBook in online reader or directly download on the web page. Select files or add your book in reader. Download and read online ebook X-Ray Phase Contrast Imaging write by Alesssandro Olivo. This book was released on 2013-07-31. X-Ray Phase Contrast Imaging available in PDF, EPUB and Kindle. This book fills an important gap in the existing literature by providing a comprehensive discussion of X-ray Phase Contrast Imaging (XPCi) and its various uses and implementations. XPCi could revolutionise all applications of X-ray imaging. It exploits a different mechanism to generate image contrast (refraction/interference instead of absorption), thus enhancing the visibility of all details, allowing the detection of features that are classically considered invisible. XPCi emerged in the mid-1990s, primarily at synchrotron radiation facilities. Initially, its use was considered to be very restricted due to the stringent requirements imposed on the radiation source. New methods which allow XPCi to be used with conventional X-ray sources have recently emerged, thus providing concrete possibilities for transfer into mainstream applications. This has renewed enthusiasm in the field and spawned a large number of new research groups worldwide. This book follows a historical perspective and describes all possible implementations of XPCi. In each case, the underpinning theory is described, the possible experimental realisations are discussed and the targeted applications listed, with specific mentions of the most significant examples. Although sometimes overlooked, X-ray imaging is all-pervasive in our society: medicine, industrial scans, non-destructive testing, security inspections and a vast number of scientific fields rely heavily on it. Hence, the potential impact of XPCi is immense.
