DIAD-Dual Imaging and Diffraction Beamline
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Himanshu
Vashishtha
,
Parastoo
Jamshidi
,
Anastasia
Vrettou
,
Anna
Kareer
,
Michael
Goode
,
Hans
Deyhle
,
Andrew
James
,
Sharif
Ahmed
,
Christina
Reinhard
,
Moataz M.
Attallah
,
David M.
Collins
Diamond Proposal Number(s):
[28029]
Open Access
Abstract: This study explores cardiovascular stents fabricated using laser powder bed fusion (LPBF) which is an emerging method to offer patient-specific customisable parts. Here, the shape memory alloy NiTi, in a near equiatomic composition, was investigated to deconvolve the material response from macroscopic component effects. Specifically, stress-geometry interactions were revealed, in-situ, for a minaturised cardiovascular stent subjected to an externally applied cylindrical stress whilst acquiring synchrotron X-ray imaging and diffraction data. The approach enabled the collection of spatially resolved micromechanical deformation data; the formation of stress-induced martensite and R-phase was evident, occurring in locations near junctions between stent ligaments where stress concentrations exist. In the as-fabricated condition, hardness maps were obtained through nanoindentation, demonstrating that the localised deformation and deformation patterning is further controlled by porosity and microstructural heterogeneity. Electron backscatter diffraction (EBSD) supported these observations, showing a finer grain structure near stent junctions with higher associated lattice curvature. These features, combined with stress concentrations when loaded will initiate localised phase transformations. If the stent was subjected to repeated loading, representing in-vivo conditions, these regions would be susceptible to cyclic damage through transformation memory loss, leading to premature component failure. This study highlights the challenges that must be addressed for the post-processing treatment of LPBF-processed stents for healthcare-related applications.
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Jul 2024
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DIAD-Dual Imaging and Diffraction Beamline
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Cyril
Besnard
,
Ali
Marie
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Sisini
Sasidharan
,
Hans
Deyhle
,
Andrew M.
James
,
Sharif I.
Ahmed
,
Christina
Reinhard
,
Robert A.
Harper
,
Richard M.
Shelton
,
Gabriel
Landini
,
Alexander M.
Korsunsky
Diamond Proposal Number(s):
[28054]
Open Access
Abstract: The Dual Imaging and Diffraction (DIAD) beamline at Diamond Light Source (Didcot, U.K.) implements a correlative approach to the dynamic study of materials based on concurrent analysis of identical sample locations using complementary X-ray modalities to reveal structural detail at various length scales. Namely, the underlying beamline principle and its practical implementation allow the collocation of chosen regions within the sample and their interrogation using real-space imaging (radiography and tomography) and reciprocal space scattering (diffraction). The switching between the two principal modes is made smooth and rapid by design, so that the data collected is interlaced to obtain near-simultaneous multimodal characterization. Different specific photon energies are used for each mode, and the interlacing of acquisition steps allows conducting static and dynamic experiments. Building on the demonstrated realization of this state-of-the-art approach requires further refining of the experimental practice, namely, the methods for gauge volume collocation under different modes of beam–sample interaction. To address this challenge, experiments were conducted at DIAD devoted to the study of human dental enamel, a hierarchical structure composed of hydroxyapatite mineral nanocrystals, as a static sample previously affected by dental caries (tooth decay) as well as under dynamic conditions simulating the process of acid demineralization. Collocation and correlation were achieved between WAXS (wide-angle X-ray scattering), 2D (radiographic), and 3D (tomographic) imaging. While X-ray imaging in 2D or 3D modes reveals real-space details of the sample microstructure, X-ray scattering data for each gauge volume provided statistical nanoscale and ultrastructural polycrystal reciprocal-space information such as phase and preferred orientation (texture). Careful registration of the gauge volume positions recorded during the scans allowed direct covisualization of the data from two modalities. Diffraction gauge volumes were identified and visualized within the tomographic data sets, revealing the underlying local information to support the interpretation of the diffraction patterns. The present implementation of the 4D microscopy paradigm allowed following the progression of demineralization and its correlation with time-dependent WAXS pattern evolution in an approach that is transferable to other material systems.
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Mar 2024
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B16-Test Beamline
I12-JEEP: Joint Engineering, Environmental and Processing
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Diamond Proposal Number(s):
[27987, 20763, 27144, 31131]
Abstract: 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.
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Oct 2022
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DIAD-Dual Imaging and Diffraction Beamline
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Diamond Proposal Number(s):
[30995]
Open Access
Abstract: The DIAD beamline for Dual Imaging and Diffraction at Diamond Light Source has opted to use an industrial robot to position its Dectris Pilatus 2M CdTe diffraction detector. This setup was chosen to enable flexible positioning of the detector in a quarter-sphere around the sample position whilst reliably holding the large weight of 139 kg of detector, detector mount and cabling in a stable position. Metrology measurements showed that the detector can be positioned with a linear repeatability of <19.7 µm and a rotational repeatability of <16.3 µrad. The detector position stays stable for a 12 h period with <10.1 µm of movement for linear displacement and <3.8 µrad for rotational displacement. X-ray diffraction from calibration samples confirmed that the robot is sufficiently stable to resolve lattice d-spacings within the instrumental broadening given by detector position and beam divergence.
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Jul 2022
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Metrology
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Open Access
Abstract: X-ray computed tomography (XCT) is increasingly used for dimensional metrology, where it can offer accurate measurements of internal features that are not accessible with other techniques. However, XCT scanning can be relatively slow, which often prevents routine uptake for many applications. This paper explores the feasibility of improving the speed of XCT measurements whilst maintaining the quality of the dimensional measurements derived from reconstructed volumes. In particular, we compare two approaches to fast XCT acquisition, the use of fewer XCT projections as well as the use of shortened x-ray exposure times for each projection. The study shows that the additional Poisson noise produced by reducing the exposure for each projection has significantly less impact on dimensional measurements compared to the artefacts associated with strategies that take fewer projection images, leading to about half the measurement error variability. Advanced reconstruction algorithms such as the conjugate gradient least squares method or total variation constrained approaches, are shown to allow further improvements in measurement speed, though this can come at the cost of increased measurement bias (e.g. 2.8 % increase in relative error in one example) and variance (e.g. 25 % in the same example).
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Jun 2022
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DIAD-Dual Imaging and Diffraction Beamline
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Christina
Reinhard
,
Michael
Drakopoulos
,
Sharif I.
Ahmed
,
Hans
Deyhle
,
Andrew
James
,
Christopher M.
Charlesworth
,
Martin
Burt
,
John
Sutter
,
Steven
Alexander
,
Peter
Garland
,
Thomas
Yates
,
Russell
Marshall
,
Ben
Kemp
,
Edmund
Warrick
,
Armando
Pueyos
,
Ben
Bradnick
,
Maurizio
Nagni
,
A. Douglas
Winter
,
Jacob
Filik
,
Mark
Basham
,
Nicola
Wadeson
,
Oliver N. F.
King
,
Navid
Aslani
,
Andrew J.
Dent
Open Access
Abstract: The Dual Imaging and Diffraction (DIAD) beamline at Diamond Light Source is a new dual-beam instrument for full-field imaging/tomography and powder diffraction. This instrument provides the user community with the capability to dynamically image 2D and 3D complex structures and perform phase identification and/or strain mapping using micro-diffraction. The aim is to enable in situ and in operando experiments that require spatially correlated results from both techniques, by providing measurements from the same specimen location quasi-simultaneously. Using an unusual optical layout, DIAD has two independent beams originating from one source that operate in the medium energy range (7–38 keV) and are combined at one sample position. Here, either radiography or tomography can be performed using monochromatic or pink beam, with a 1.4 mm × 1.2 mm field of view and a feature resolution of 1.2 µm. Micro-diffraction is possible with a variable beam size between 13 µm × 4 µm and 50 µm × 50 µm. One key functionality of the beamline is image-guided diffraction, a setup in which the micro-diffraction beam can be scanned over the complete area of the imaging field-of-view. This moving beam setup enables the collection of location-specific information about the phase composition and/or strains at any given position within the image/tomography field of view. The dual beam design allows fast switching between imaging and diffraction mode without the need of complicated and time-consuming mode switches. Real-time selection of areas of interest for diffraction measurements as well as the simultaneous collection of both imaging and diffraction data of (irreversible) in situ and in operando experiments are possible.
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Nov 2021
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Open Access
Abstract: Purpose: In dental offices, there is a trend replacing conventional silicone impressions and plaster cast models by imaging data of intraoral scanners to map the denture and surrounding tissues. The aim of the study is the analysis of the accuracy of selected commercially available scanners. The accuracy is considered as the main drawback in comparison to the conventional approach.
Approach: We evaluated the reproduction performance of five optical scanners by a direct comparison with high-resolution hard x-ray computed tomography data, all obtained from a polyetheretherketone model with similarity to a full-arch upper jaw.
Results: Using the software GOM Inspect (GOM GmbH, Braunschweig, Germany), we could classify the intraoral scanners into two groups. The more accurate instruments gave rise to the following precision values: 35 μm (TRIOS® 3, 3shape, Copenhagen, Denmark), 43 μm (CS 3600, Carestream, Atlanta, Georgia), and 46 μm (3M™ True Definition Scanner, 3M ESPE, St. Paul, Minnesota). The less precise systems yielded 93 μm (Medit i500, Medit corp., Seongbuk-gu, South Korea) and 97 μm (Emerald™, Planmeca Oy, Helsinki, Finland).
Conclusions: The selected scanners are suitable for single crowns, small bridges, and separate quadrants prostheses. Scanners based on triangulation are hardly appropriate for full-arch prostheses. Besides precision, however, the choice of the scanner depends on scanning time, intraoral-camera size, and the user’s learning curve. The developed protocol, which includes three-dimensional (3D) imaging and advanced computational tools for the registration with the design data, will be increasingly used in geometrical metrology by nondestructive procedures to perform dimensional measurements with micrometer precision and is capable for detailed 3D geometrical models reconstruction.
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May 2021
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I13-2-Diamond Manchester Imaging
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Diamond Proposal Number(s):
[19829, 20746]
Abstract: Hard x-ray tomography with Paganin's widespread single-distance phase retrieval filter improves the contrast-to-noise ratio (CNR) while reducing spatial resolution (SR). We demonstrate that a Gaussian filter provided larger CNR at high SR with interpretable density measurements for two medically relevant soft tissue samples. Paganin's filter produced larger CNR at low SR, though a priori assumptions were generally false and image quality gains diminish for CNR > 1. Therefore, simple absorption measurements of low-Z specimens combined with Gaussian filtering can provide improved image quality and model-independent density measurements compared to single-distance phase retrieval.
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Jan 2020
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I13-2-Diamond Manchester Imaging
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Diamond Proposal Number(s):
[19829]
Abstract: X-ray grating interferometry (XGI) is a phase-contrast imaging technique that allows for a quantitative measurement of the refractive index with high density resolution in a model-independent manner—i.e. without a priori knowledge of the specimen composition. However, the retrieval of the X-ray wavefront phase shift relies on the accurate measurement of the interference pattern phase shift, making XGI vulnerable to phase wrapping when the interference pattern phase shift, related to the derivative of the wavefront phase shift, is large. Standard procedure for avoiding phase wrapping involves submerging the specimen in a water bath to reduce the mismatch of the index of refraction at the boundaries, but this requires a top-down rotation stage and is susceptible to gas bubble formation inside the water bath. Our team has presented an algorithm to remove phase wrapping artifacts for cylindrically shaped specimens that is applied to the phase-retrieved sinogram. This algorithm models and replaces phase-wrapped data to prevent the spread of “cupping” artifacts due to the integration of the differential phase during reconstruction. We give a criterion for selecting the modeling parameters so that the resulting measurement of the index of refraction matches the results of measurements without phase wrapping. We also apply this technique to cases where phase wrapping occurs at multiple interfaces. This algorithm allows for XGI measurements without a water bath and top-down rotation stage at synchrotron and laboratory facilities, especially as sensitivity increases.
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Sep 2019
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I13-2-Diamond Manchester Imaging
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Christos
Bikis
,
Griffin
Rodgers
,
Hans
Deyhle
,
Peter
Thalmann
,
Alexander
Hipp
,
Felix
Beckmann
,
Timm
Weitkamp
,
Stamatios
Theocharis
,
Christoph
Rau
,
Georg
Schulz
,
Bert
Muller
Diamond Proposal Number(s):
[19829]
Open Access
Abstract: Advances in high-resolution hard X-ray computed tomography have led to the field of virtual histology to complement histopathological analyses. Phase-contrast modalities have been favored because, for soft tissues, the real part of the refractive index is orders of magnitude greater than the imaginary part. Nevertheless, absorption-contrast measurements of paraffin-embedded tissues have provided exceptionally high contrast combined with a submicron resolution. In this work, we present a quantitative comparison of phase tomography using synchrotron radiation-based X-ray double grating interferometry and conventional synchrotron radiation-based computed tomography in the context of histopathologically relevant paraffin-embedded human brain tissue. We determine the complex refractive index and compare the contrast-to-noise ratio (CNR) of each modality, accounting for the spatial resolution and optimizing the photon energy for absorption tomography. We demonstrate that the CNR in the phase modality is 1.6 times higher than the photon-energy optimized and spatial resolution-matched absorption measurements. We predict, however, that a further optimized phase tomography will provide a CNR gain of 4. This study seeks to boost the discussion of the relative merits of phase and absorption modalities in the context of paraffin-embedded tissues for virtual histology, highlighting the importance of optimization procedures for the two complementary modes and the trade-off between spatial and density resolution, not to mention the disparity in data acquisition and processing.
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Feb 2019
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