X-ray phase-contrast tomography (X-PCT) techniques are capable of imaging samples with small differences in densities. They enable scientists to study biological or medical samples using high energy X-rays, which means less X-ray absorption and less sample damage, with high contrast quality. One branch of these techniques known as speckle-based methods have been well developed and demonstrated on real applications by different groups of developers using their own codes. However, there is lack of collective effort to package these methods into an open-source software which is easy-to-install, easy-to-use, well-documented, and optimized for speed. Such software is crucial to make the X-PCT techniques accessible to generic users and become regular tools. This report demonstrates the effort which implements speckle-based phase-retrieval methods in Python and GPU.
X-ray speckle-based imaging (SBI), one of them most recent phase-contrast imaging methods, has received growing interest in the last years. Its simplicity, cost-effectiveness and robustness combined with the high phase sensitivity and compatibility with laboratory X-ray sources make it an attractive method for visualising even minute density differences in samples. Since its first demonstration, SBI has seen rapid development and a range of applications have been identified. Among the various ways to perform SBI, the unified modulated pattern analysis (UMPA) offers a number of advantages. Here, we present an overview of the state of the art of SBI, including some of our work using UMPA in the recent years. We demonstrate the potential of UMPA for applications such as optics characterisation, biomedical and geological imaging and discuss its translation from large-scale synchrotron facilities to the laboratory.
The DIAMOND beamline I13L is dedicated to multi-scale and multi-modal imaging in real and reciprocal space. The beamline consists of two independently operating experimental stations, located at a distance of more than 200 m from the source. The Imaging Branch performs micro-tomography with in-line phase contrast in the 6-30 keV energy range. In addition, a grating interferometry setup and a full-field microscope for nano-tomography are currently implemented. Other techniques providing high-resolution three-dimensional information, in particular coherent X-ray diffraction, are hosted on the Coherence Branch. All imaging methods are tested to operate with large energy bandwidths and therefore shorter exposure times. To this end, two options are currently used: the so-called ‘pink-beam’ mode using a reflecting mirror and X-ray filters and monochromatic mode using a multilayer monochromator. The operation mode enables science for in-situ and operando studies across a wide range of scientific areas.
The Diamond Beamline I13L is dedicated to micro- and nano- imaging, with two independently operating branchlines. The imaging branch preforms imaging in real space, with In-line phase contrast imaging and grating interferometry at micrometre resolution and full-field transmission microscopy up to 50nm spatial resolution. Highest spatial resolution is achieved on the coherence branchline, where diffraction imaging methods such as Ptychography and Bragg-CDI are performed. The article provides an update about the experimental capabilities at the beamline with an emphasis on the rapidly evolving ptychography capabilities. The latter has evolved to an user-friendly method with non-expert users able to explore their science without any specific a-priory knowledge.
The Diamond Beamline I13L is dedicated to imaging on the micro- and nano-lengthsale, operating in the energy range
between 6 and 30keV. For this purpose two independently operating branchlines and endstations have been built. The
imaging branch is fully operational for micro-tomography and in-line phase contrast imaging with micrometre
resolution. Grating interferometry is currently implemented, adding the capability of measuring phase and small-angle
information. For tomography with increased resolution a full-field microscope providing 50nm spatial resolution with a
field of view of 100μm is being tested. The instrument provides a large working distance between optics and sample to
adapt a wide range of customised sample environments. On the coherence branch coherent diffraction imaging
techniques such as ptychography, coherent X-ray diffraction (CXRD) are currently developed for three dimensional
imaging with the highest resolution.
The imaging branch is operated in collaboration with Manchester University, called therefore the Diamond-Manchester
Branchline. The scientific applications cover a large area including bio-medicine, materials science, chemistry geology
and more. The present paper provides an overview about the current status of the beamline and the science addressed.
The phase-stepping (PS) mode of X-ray Grating Talbot interferometer (XGTI) data processing technique can yield
high-spatial resolution images, albeit with lower throughput since each projection of a tomogram requires at least five
phase-stepping images. To overcome this problem, we can use a setup with only a single phase grating in combination
with a high-resolution detector system and a Spatial Harmonic Imaging (SHI) technique. The latter technique makes use
of the fact that a Talbot interferogram consists of carrier frequency spectrum of the grating overlapping with the sample
spectrum and by Fourier transforming the interferogram we can separate the two. The disadvantage of this is that the
spatial resolution is inferior. In this manuscript we will compare these two single grating data processing techniques
using a single data set measured with mouse embryo heart and discuss advantages and disadvantages of each technique.
These two techniques can be used as complementary; one for high resolution, and the other for high-speed imaging.
The Diamond Beamline I13L is designed to imaging on the micron- and nano-lengthsale with X-rays of energies between 6 and 30 keV [1]. Two independently operating branchlines and endstations have been built at distance of more than 200m from the source for this purpose. The imaging branch is dedicated for imaging in real space, providing In-line phase contrast imaging and grating interferometry with micrometre resolution and full-field transmission microscopy with 50nm spatial resolution.
On the coherence branch coherent diffraction imaging techniques such as ptychography, coherent X-ray diffraction (CXRD) and Fourier-Transform holography are currently developed. Because of the large lateral coherence length available at I13, the beamline hosts numerous microscopy experiments. The coherence branchline in particular contains a number of unique features. New instrumental designs have been employed such as a robot arm for the detector in diffraction experiments and a photon counting detector for diffraction experiments. The so-called ‘mini-beta’ layout in the straight section of the electron storage ring permits modulating the horizontal source size and therefor the lateral coherence length.
We will present the recent progress in coherent imaging at the beamline and the sciences addressed with the instrumental capabilities.
Reference:
[1] C. Rau, U. Wagner, Z. Pesic, A. De Fanis Physica Status Solidi (a) 208 (11). Issue 11 2522-2525, 2011, 10.1002/pssa.201184272
Among the clinically relevant imaging techniques, computed tomography (CT) reaches the best spatial resolution. Sub-millimeter voxel sizes are regularly obtained. For investigations on true micrometer level lab-based μCT has become gold standard. The aim of the present study is the hierarchical investigation of a human knee post mortem using hard X-ray μCT. After the visualization of the entire knee using a clinical CT with a spatial resolution on the sub-millimeter range, a hierarchical imaging study was performed using a laboratory μCT system nanotom m. Due to the size of the whole knee the pixel length could not be reduced below 65 μm. These first two data sets were directly compared after a rigid registration using a cross-correlation algorithm. The μCT data set allowed an investigation of the trabecular structures of the bones. The further reduction of the pixel length down to 25 μm could be achieved by removing the skin and soft tissues and measuring the tibia and the femur separately. True micrometer resolution could be achieved after extracting cylinders of several millimeters diameters from the two bones. The high resolution scans revealed the mineralized cartilage zone including the tide mark line as well as individual calcified chondrocytes. The visualization of soft tissues including cartilage, was arranged by X-ray grating interferometry (XGI) at ESRF and Diamond Light Source. Whereas the high-energy measurements at ESRF allowed the simultaneous visualization of soft and hard tissues, the low-energy results from Diamond Light Source made individual chondrocytes within the cartilage visual.
X-ray imaging in absorption contrast mode is well established for hard tissue visualization. However, performance
for lower density materials is limited due to a reduced contrast. Our aim is three-dimensional (3D)
characterization of micro-morphology of human brain tissues down to (sub-)cellular resolution within a laboratory
environment. Using the laboratory-based microtomography (μCT) system nanotom m (GE Sensing
and Inspection Technologies GmbH, Wunstorf, Germany) and synchrotron radiation at the Diamond-Manchester
Imaging Branchline I13-2 (Diamond Light Source, Didcot, UK), we have acquired 3D data with a resolution
down to 0.45 μm for visualization of a human cerebellum specimen down to cellular level. We have shown that
all selected modalities, namely laboratory-based absorption contrast micro-tomography (LBμCT), synchrotron
radiation based in-line single distance phase contrast tomography (SDPR) and synchrotron radiation based
single-grating interferometry (GI), can reach cellular resolution for tissue samples with a size in the mm-range.
The results are discussed qualitatively in comparison to optical microscopy of haematoxylin and eosin (HE)
stained sections. As phase contrast yields to a better data quality for soft tissues and in order to overcome
restrictions of limited beamline access for phase contrast measurements, we have equipped the μCT system
nanotom m with a double-grating phase contrast set-up. Preliminary experimental results of a knee sample
consisting of a bony part and a cartilage demonstrate that phase contrast data exhibits better quality compared
to absorption contrast. Currently, the set-up is under adjustment. It is expected that cellular resolution would
also be achieved. The questions arise (1) what would be the quality gain of laboratory-based phase contrast in
comparison to laboratory-based absorption contrast tomography and (2) could laboratory-based phase contrast
data provide comparable results to synchrotron radiation based phase contrast data.
Cell visualization and counting plays a crucial role in biological and medical research including the study of neurodegenerative diseases. The neuronal cell loss is typically determined to measure the extent of the disease. Its characterization is challenging because the cell density and size already differs by more than three orders of magnitude in a healthy cerebellum. Cell visualization is commonly performed by histology and fluorescence microscopy. These techniques are limited to resolve complex microstructures in the third dimension. Phase- contrast tomography has been proven to provide sufficient contrast in the three-dimensional imaging of soft tissue down to the cell level and, therefore, offers the basis for the three-dimensional segmentation. Within this context, a human cerebellum sample was embedded in paraffin and measured in local phase-contrast mode at the beamline ID19 (ESRF, Grenoble, France) and the Diamond Manchester Imaging Branchline I13-2 (Diamond Light Source, Didcot, UK). After the application of Frangi-based filtering the data showed sufficient contrast to automatically identify the Purkinje cells and to quantify their density to 177 cells per mm3 within the volume of interest. Moreover, brain layers were segmented in a region of interest based on edge detection. Subsequently performed histological analysis validated the presence of the cells, which required a mapping from the two- dimensional histological slices to the three-dimensional tomogram. The methodology can also be applied to further tissue types and shows potential for the computational tissue analysis in health and disease.
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