ORCID Profile
0000-0002-1756-4406
Current Organisations
Monash University
,
University of New England
,
University of Canterbury
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Research Topics
In Research Link Australia (RLA), "Research Topics" refer to ANZSRC FOR and SEO codes. These topics are either sourced from ANZSRC FOR and SEO codes listed in researchers' related grants or generated by a large language model (LLM) based on their publications.
Top 5 Research Topics
ANZSRC Field of Research (FoR)
Other Physical Sciences | Nanotechnology | Optical Physics | Materials Engineering | Materials Engineering Not Elsewhere Classified | Synchrotrons; Accelerators; Instruments and Techniques | Optical Physics Not Elsewhere Classified | Instruments And Techniques
ANZSRC Socio-Economic Objective (SEO)
Scientific instrumentation | Expanding Knowledge in the Earth Sciences | Expanding Knowledge in the Chemical Sciences | Expanding Knowledge in the Physical Sciences | Medical instrumentation | Physical sciences |
Related Links
Publications
Deterministic Retrieval of Complex Green's Functions Using Hard X Rays
Publisher: American Physical Society (APS)
Date: 26-01-2009
Sulphur-passivated GaAs investigation using high resolution X-ray diffractometry
Publisher: World Scientific Pub Co Pte Lt
Date: 05-2011
DOI: 10.1142/S0218625X03005219
Abstract: The growth of a MoS 2 layer on a GaAs(111) substrate produces a highly strained interface layer, which relaxes via generation of dislocations. Using high-resolution X-ray diffractometry in the triple-axis scheme we investigated this interfacial layer, which results from dipping an epi-ready GaAs wafer in ammonium sulphide, followed by deposition of an RF-sputtered MoS 2 layer. The dislocation density revealed from the measurements is of the 10 6 cm -2 . This suggests that high efficiency (~20%) MoS 2 /GaAs heterojunction photovoltaic devices are feasible.
Theory of X-ray diffraction on a lateral crystal with elastically bent lattice planes
Publisher: Pleiades Publishing Ltd
Date: 09-2006
Advantages of breast cancer visualization and characterization using synchrotron radiation phase-contrast tomography
Publisher: International Union of Crystallography (IUCr)
Date: 13-08-2018
DOI: 10.1107/S1600577518010172
Abstract: The aim of this study was to highlight the advantages that propagation-based phase-contrast computed tomography (PB-CT) with synchrotron radiation can provide in breast cancer diagnostics. For the first time, a fresh and intact mastectomy s le from a 60 year old patient was scanned on the IMBL beamline at the Australian Synchrotron in PB-CT mode and reconstructed. The clinical picture was described and characterized by an experienced breast radiologist, who underlined the advantages of providing diagnosis on a PB-CT volume rather than conventional two-dimensional modalities. Subsequently, the image quality was assessed by 11 breast radiologists and medical imaging experts using a radiological scoring system. The results indicate that, with the radiation dose delivered to the s le being equal, the accuracy of a diagnosis made on PB-CT images is significantly higher than one using conventional techniques.
Investigation of the imaging quality of synchrotron-based phase-contrast mammographic tomography
Publisher: IOP Publishing
Date: 20-08-2014
Dark-field tomography of an attenuating object using intrinsic x-ray speckle tracking
Publisher: SPIE-Intl Soc Optical Eng
Date: 07-02-2022
Wide angle X-ray dynamical diffraction by deformed crystals: recurrence relations
Publisher: Wiley
Date: 08-2007
Darwin's approach to X-ray diffraction on lateral crystalline structures
Publisher: International Union of Crystallography (IUCr)
Date: 20-12-2014
A non-iterative reconstruction method for direct and unambiguous coherent diffractive imaging
Publisher: The Optical Society
Date: 2007
DOI: 10.1364/OE.15.009954
Abstract: We develop a deterministic algorithm for coherent diffractive imaging (CDI) that employs a modified Fourier transform of a Fraunhofer diffraction pattern to quantitatively reconstruct the complex scalar wavefield at the exit surface of a s le of interest. The s le is placed in a uniformly-illuminated rectangular hole with dimensions at least two times larger than the s le. For this particular scenario, and in the far-field diffraction case, our non-iterative reconstruction algorithm is rapid, exact and gives a unique analytical solution to the inverse problem. The efficacy and stability of the algorithm, which may achieve resolutions in the nanoscale range, is demonstrated using simulated X-ray data.
X-ray multi-modal intrinsic-speckle-tracking
Publisher: IOP Publishing
Date: 11-11-2020
Abstract: We develop x-ray multi-modal intrinsic-speckle-tracking (MIST), a form of x-ray speckle-tracking that is able to recover both the position-dependent phase shift and the position-dependent small-angle x-ray scattering (SAXS) signal of a phase object. MIST is based on combining a Fokker–Planck description of paraxial x-ray optics, with an optical-flow formalism for x-ray speckle-tracking. Only two images need to be taken in the presence of the s le, corresponding to two different transverse positions of the speckle-generating membrane, in order to recover both the refractive and local-SAXS properties of the s le. Like the optical-flow x-ray phase-retrieval method which it generalises, the MIST method implicitly rather than explicitly tracks both the transverse motion and the diffusion of speckles that is induced by the presence of a s le. Application to x-ray synchrotron data shows the method to be efficient, rapid and stable.
Mask-assisted deterministic phase–amplitude retrieval from a single far-field intensity diffraction pattern: Two experimental proofs of principle using visible light
Publisher: Elsevier BV
Date: 06-2011
DOI: 10.1016/J.ULTRAMIC.2011.01.011
Abstract: We recently developed a simple closed-form algorithm, which allows one to reconstruct the complex scalar wavefield at the exit surface of a s le, from the intensity of its far-field coherent diffraction pattern which is obtained in the presence of a suitable object-plane mask. In the first variant of this algorithm, the s le is contained within a uniformly illuminated sharp rectangular aperture in which at least one transverse dimension is at least twice that of the object. In the second variant, the s le is uniformly illuminated and is transversely displaced from an opaque rectangular mask in the object plane. For both variants, the far-field diffraction pattern is first Fourier transformed and then differentiated with respect to both transverse coordinates, in order to deterministically yield a series of independent reconstructions of the s le. Here we give an experimental demonstration of each of these two variants of our technique, using visible light.
Phase-contrast X-ray tomography using Teague’s method
Publisher: The Optical Society
Date: 11-07-2012
DOI: 10.1364/OE.20.016913
Deterministic Bragg Coherent Diffraction Imaging
Publisher: Springer Science and Business Media LLC
Date: 25-04-2017
DOI: 10.1038/S41598-017-01164-X
Abstract: A deterministic variant of Bragg Coherent Diffraction Imaging is introduced in its kinematical approximation, for X-ray scattering from an imperfect crystal whose imperfections span no more than half of the volume of the crystal. This approach provides a unique analytical reconstruction of the object’s structure factor and displacement fields from the 3D diffracted intensity distribution centred around any particular reciprocal lattice vector. The simple closed-form reconstruction algorithm, which requires only one multiplication and one Fourier transformation, is not restricted by assumptions of smallness of the displacement field. The algorithm performs well in simulations incorporating a variety of conditions, including both realistic levels of noise and departures from ideality in the reference (i.e. imperfection-free) part of the crystal.
Unambiguous reconstruction of the complex amplitude reflection coefficient of a laterally homogeneous crystal using analyser-based phase-contrast imaging
Publisher: International Union of Crystallography (IUCr)
Date: 13-07-2007
DOI: 10.1107/S0021889807021097
Abstract: A theoretical approach is developed to invert analytically a hard X-ray analyser-based phase-contrast image of a known weak object to recover the complex litude reflection coefficient (ARC) of a laterally homogeneous crystal. Numerical simulations test the method to recover the ARC from two systems of interest: a thick perfect crystal and a linearly strained thin film. For the latter model, a kinematical diffraction approximation was used to recover the one-dimensional deformation profile from the ARC.
Phase retrieval using coherent imaging systems with linear transfer functions
Publisher: Elsevier BV
Date: 04-2004
On the derivation of the Green’s function for the Helmholtz equation using generalized functions
Publisher: American Association of Physics Teachers (AAPT)
Date: 12-01-2010
DOI: 10.1119/1.3253655
Abstract: A method for constructing the Green’s function for the Helmholtz equation in free space subject to Sommerfeld radiation conditions is presented. Unlike the methods found in many textbooks, the present technique allows us to obtain all of the possible Green’s functions before selecting the one that satisfies the choice of boundary conditions.
Imaging Breast Microcalcifications Using Dark-Field Signal in Propagation-Based Phase-Contrast Tomography
Publisher: Institute of Electrical and Electronics Engineers (IEEE)
Date: 11-2022
Tomographic phase and attenuation extraction for a sample composed of unknown materials using x-ray propagation-based phase-contrast imaging
Publisher: Optica Publishing Group
Date: 06-04-2022
DOI: 10.1364/OL.445802
Abstract: Propagation-based phase-contrast x-ray imaging (PB-PCXI) generates image contrast by utilizing s le-imposed phase-shifts. This has proven useful when imaging weakly attenuating s les, as conventional attenuation-based imaging does not always provide adequate contrast. We present a PB-PCXI algorithm capable of extracting the x-ray attenuation β and refraction δ , components of the complex refractive index of distinct materials within an unknown s le. The method involves curve fitting an error-function-based model to a phase-retrieved interface in a PB-PCXI tomographic reconstruction, which is obtained when Paganin-type phase retrieval is applied with incorrect values of δ and β . The fit parameters can then be used to calculate true δ and β values for composite materials. This approach requires no a priori s le information, making it broadly applicable. Our PB-PCXI reconstruction is single-distance, requiring only one exposure per tomographic angle, which is important for radiosensitive s les. We apply this approach to a breast-tissue s le, recovering the refraction component δ , with 0.6–2.4% accuracy compared with theoretical values.
Imaging lung aeration and lung liquid clearance at birth
Publisher: Wiley
Date: 29-05-2007
Abstract: Aeration of the lung and the transition to air-breathing at birth is fundamental to mammalian life and initiates major changes in cardiopulmonary physiology. However, the dynamics of this process and the factors involved are largely unknown, because it has not been possible to observe or measure lung aeration on a breath-by-breath basis. We have used the high contrast and spatial resolution of phase contrast X-ray imaging to study lung aeration at birth in spontaneously breathing neonatal rabbits. As the liquid-filled fetal lungs provide little absorption or phase contrast, they are not visible and only become visible as they aerate, allowing a detailed examination of this process. Pups were imaged live from birth to determine the timing and spatial pattern of lung aeration, and relative levels of lung aeration were measured from the images using a power spectral analysis. We report the first detailed observations and measurements of lung aeration, demonstrating its dependence on inspiratory activity and body position dependent regions aerated at much slower rates. The air/liquid interface moved toward the distal airways only during inspiration, with little proximal movement during expiration, indicating that trans-pulmonary pressures play an important role in airway liquid clearance at birth. Using these imaging techniques, the dynamics of lung aeration and the critical role it plays in regulating the physiological changes at birth can be fully explored.
Analyser-based phase contrast image reconstruction using geometrical optics
Publisher: IOP Publishing
Date: 15-06-2007
DOI: 10.1088/0031-9155/52/14/010
Abstract: Analyser-based phase contrast imaging can provide radiographs of exceptional contrast at high resolution (<100 microm), whilst quantitative phase and attenuation information can be extracted using just two images when the approximations of geometrical optics are satisfied. Analytical phase retrieval can be performed by fitting the analyser rocking curve with a symmetric Pearson type VII function. The Pearson VII function provided at least a 10% better fit to experimentally measured rocking curves than linear or Gaussian functions. A test phantom, a hollow nylon cylinder, was imaged at 20 keV using a Si(1 1 1) analyser at the ELETTRA synchrotron radiation facility. Our phase retrieval method yielded a more accurate object reconstruction than methods based on a linear fit to the rocking curve. Where reconstructions failed to map expected values, calculations of the Takagi number permitted distinction between the violation of the geometrical optics conditions and the failure of curve fitting procedures. The need for synchronized object/detector translation stages was removed by using a large, ergent beam and imaging the object in segments. Our image acquisition and reconstruction procedure enables quantitative phase retrieval for systems with a ergent source and accounts for imperfections in the analyser.
Characterization of InxGa1-xAs/InP epilayers by X-ray double crystal rocking curve peak profile analysis - Comment
Publisher: Elsevier BV
Date: 08-1997
Phase-Contrast Clinical Breast CT: Optimization of Imaging Setups and Reconstruction Workflows
Publisher: Springer International Publishing
Date: 2016
X-Ray diffraction analysis of multilayer InAs-GaAs heterostructures with InAs quantum dots
Publisher: Pleiades Publishing Ltd
Date: 11-1999
DOI: 10.1134/1.1187855
Deterministic X-ray Bragg coherent diffraction imaging as a seed for subsequent iterative reconstruction
Publisher: IOP Publishing
Date: 29-08-2018
Simultaneous acquisition of dual analyser-based phase contrast X-ray images for small animal imaging
Publisher: Elsevier BV
Date: 12-2008
DOI: 10.1016/J.EJRAD.2008.04.028
Abstract: Analyser-based phase contrast X-ray imaging can provide high-contrast images of biological tissues with exquisite sensitivity to the boundaries between tissues. The phase and absorption information can be extracted by processing multiple images acquired at different analyser orientations. Recording both the transmitted and diffracted beams from a thin Laue analyser crystal can make phase retrieval possible for dynamic systems by allowing full field imaging. This technique was used to image the thorax of a mechanically ventilated newborn rabbit pup using a 25 keV beam from the SPring-8 synchrotron radiation facility. The diffracted image was produced from the (111) planes of a 50 mm x 40 mm, 100 microm thick Si analyser crystal in the Laue geometry. The beam and analyser were large enough to image the entire chest, making it possible to observe changes in anatomy with high contrast and spatial resolution.
Ga droplet morphology on GaAs(001) studied by Lloyd's mirror photoemission electron microscopy
Publisher: IOP Publishing
Date: 07-07-2009
DOI: 10.1088/0953-8984/21/31/314022
Abstract: We apply Lloyd's mirror photoemission electron microscopy (PEEM) to study the surface shape of Ga droplets on GaAs(001). An unusual rectangular-based droplet shape is identified and the contact angle is determined in situ. It is shown that quenching does not appreciably affect droplet shape and ex situ measurements of the contact angle by atomic force microscopy are in good agreement with Lloyd's mirror PEEM. Extension of Lloyd's mirror technique to reconstruct general three-dimensional (3D) surface shapes and the potential use of synchrotron radiation to improve vertical resolution is discussed.
Computed tomography with linear shift-invariant optical systems
Publisher: Optica Publishing Group
Date: 11-07-2007
Abstract: Optical systems capable of three-dimensional transmission imaging are considered these systems employ a conventional tomographic setup with an added linear shift-invariant optical system between the s le and the detector. A theoretical analysis is presented of image formation and s le reconstruction in such systems, ex les of which include diffraction tomography and phase-contrast tomography with the use of analyzer crystals. An ex le is introduced in which the image is obtained by scanning the beam along the line orthogonal to the optic axis and to the axis of rotation with a one-dimensional slit or grating parallel to the rotation axis. We show that under certain conditions the proposed system may allow quantitative local (region-of-interest) tomography.
The equations of the statistical dynamical theory of X-ray diffraction for deformed crystals
Publisher: International Union of Crystallography (IUCr)
Date: 03-1998
X-ray phase, absorption and scatter retrieval using two or more phase contrast images
Publisher: The Optical Society
Date: 03-09-2010
DOI: 10.1364/OE.18.019994
A new approach to wide-angle dynamical X-ray diffraction by deformed crystals
Publisher: International Union of Crystallography (IUCr)
Date: 12-09-2006
DOI: 10.1107/S0021889806025696
Abstract: A new approach is proposed for X-ray dynamical diffraction theory in distorted crystals. The theory allows one to perform dynamical diffraction simulations between Bragg peaks for non-ideal crystals, using a simple approach of two distorted waves. It can be directly applied for reciprocal-space simulation. The formalism is used to analyse high-resolution X-ray diffraction data, obtained for an InSb/InGaSb/InSb/InAs superlattice grown on top of a GaSb buffer layer on a (001) GaSb substrate.
Multimodal intrinsic speckle-tracking (MIST) to extract images of rapidly-varying diffuse X-ray dark-field
Publisher: Springer Science and Business Media LLC
Date: 03-04-2023
DOI: 10.1038/S41598-023-31574-Z
Abstract: Speckle-based phase-contrast X-ray imaging (SB-PCXI) can reconstruct high-resolution images of weakly-attenuating materials that would otherwise be indistinguishable in conventional attenuation-based X-ray imaging. The experimental setup of SB-PCXI requires only a sufficiently coherent X-ray source and spatially random mask, positioned between the source and detector. The technique can extract s le information at length scales smaller than the imaging system’s spatial resolution this enables multimodal signal reconstruction. “Multimodal Intrinsic Speckle-Tracking” (MIST) is a rapid and deterministic formalism derived from the paraxial-optics form of the Fokker–Planck equation. MIST simultaneously extracts attenuation, refraction, and small-angle scattering (diffusive dark-field) signals from a s le and is more computationally efficient compared to alternative speckle-tracking approaches. Hitherto, variants of MIST have assumed the diffusive dark-field signal to be spatially slowly varying. Although successful, these approaches have been unable to well-describe unresolved s le microstructure whose statistical form is not spatially slowly varying. Here, we extend the MIST formalism such that this restriction is removed, in terms of a s le’s rotationally-isotropic diffusive dark-field signal. We reconstruct multimodal signals of two s les, each with distinct X-ray attenuation and scattering properties. The reconstructed diffusive dark-field signals have superior image quality—as measured by the naturalness image quality evaluator, signal-to-noise ratio, and azimuthally averaged power-spectrum—compared to our previous approaches which assume the diffusive dark-field to be a slowly varying function of transverse position. Our generalisation may assist increased adoption of SB-PCXI in applications such as engineering and biomedical disciplines, forestry, and palaeontology, and is anticipated to aid the development of speckle-based diffusive dark-field tensor tomography.
Free propagation phase-contrast breast CT provides higher image quality than cone-beam breast-CT at low radiation doses: a feasibility study on human mastectomies
Publisher: Springer Science and Business Media LLC
Date: 24-09-2019
DOI: 10.1038/S41598-019-50075-6
Abstract: In this study we demonstrate the first direct comparison between synchrotron x-ray propagation-based CT (PB-CT) and cone-beam breast-CT (CB-CT) on human mastectomy specimens (N = 12) including different benign and malignant lesions. The image quality and diagnostic power of the obtained data sets were compared and judged by two independent expert radiologists. Two cases are presented in detail in this paper including a comparison with the corresponding histological evaluation. Results indicate that with PB-CT it is possible to increase the level of contrast-to-noise ratio (CNR) keeping the same level of dose used for the CB-CT or achieve the same level of CNR reached by CB-CT at a lower level of dose. In other words, PB-CT can achieve a higher diagnostic potential compared to the commercial breast-CT system while also delivering a considerably lower mean glandular dose. Therefore, we believe that PB-CT technique, if translated to a clinical setting, could have a significant impact in improving breast cancer diagnosis.
Dynamic imaging of the lungs using X-ray phase contrast
Publisher: IOP Publishing
Date: 12-10-2005
DOI: 10.1088/0031-9155/50/21/006
Abstract: High quality real-time imaging of lungs in vivo presents considerable challenges. We demonstrate here that phase contrast x-ray imaging is capable of dynamically imaging the lungs. It retains many of the advantages of simple x-ray imaging, whilst also being able to map weakly absorbing soft tissues based on refractive index differences. Preliminary results reported herein show that this novel imaging technique can identify and locate airway liquid and allows lung aeration in newborn rabbit pups to be dynamically visualized.
Effect of interfacial bonding on the structural and vibrational properties of InAs/GaSb superlattices
Publisher: American Physical Society (APS)
Date: 15-06-1996
Imaging surface topography using Lloyd's mirror in photoemission electron microscopy
Publisher: American Physical Society (APS)
Date: 05-07-2007
Three-dimensional contrast-transfer-function approach in phase-contrast tomography
Publisher: Optica Publishing Group
Date: 06-2023
DOI: 10.1364/JOSAA.494293
Abstract: A new method is developed for 3D reconstruction of multimaterial objects using propagation-based x-ray phase-contrast tomography (PB-CT) with phase retrieval via contrast-transfer-function (CTF) formalism. The approach differs from conventional PB-CT algorithms, which apply phase retrieval to in idual 2D projections. Instead, this method involves performing phase retrieval to the CT-reconstructed volume in 3D. The CTF formalism is further extended to the cases of partially coherent illumination and strongly absorbing s les. Simulated results demonstrate that the proposed post-reconstruction CTF method provides fast and stable phase retrieval, producing results equivalent to conventional pre-reconstruction 2D CTF phase retrieval. Moreover, it is shown that application can be highly localized to isolated objects of interest, without a significant loss of quality, thus leading to increased computational efficiency. Combined with the extended validity of the CTF to greater propagation distances, this method provides additional advantages over approaches based on the transport-of-intensity equation.
Implementation of an analyser crystal method for x-ray diffraction tomography
Publisher: IOP Publishing
Date: 20-03-2001
Analyser-based mammography using single-image reconstruction
Publisher: IOP Publishing
Date: 19-07-2005
DOI: 10.1088/0031-9155/50/15/008
Abstract: We implement an algorithm that is able to decode a single analyser-based x-ray phase-contrast image of a s le, converting it into an equivalent conventional absorption-contrast radiograph. The algorithm assumes the projection approximation for x-ray propagation in a single-material object embedded in a substrate of approximately uniform thickness. Unlike the phase-contrast images, which have both directional bias and a bias towards edges present in the s le, the reconstructed images are directly interpretable in terms of the projected absorption coefficient of the s le. The technique was applied to a Leeds TOR[MAM] phantom, which is designed to test mammogram quality by the inclusion of simulated microcalcifications, filaments and circular discs. This phantom was imaged at varying doses using three modalities: analyser-based synchrotron phase-contrast images converted to equivalent absorption radiographs using our algorithm, slot-scanned synchrotron imaging and imaging using a conventional mammography unit. Features in the resulting images were then assigned a quality score by volunteers. The single-image reconstruction method achieved higher scores at equivalent and lower doses than the conventional mammography images, but no improvement of visualization of the simulated microcalcifications, and some degradation in image quality at reduced doses for filament features.
A new theoretical approach to x-ray diffraction tomography
Publisher: IOP Publishing
Date: 23-06-2000
Directional dark-field implicit x-ray speckle tracking using an anisotropic-diffusion Fokker-Planck equation
Publisher: American Physical Society (APS)
Date: 02-11-2021
Combined analyser-based and propagation-based phase-contrast imaging of weak objects
Publisher: Elsevier BV
Date: 03-2006
Analyzer-based phase contrast imaging and phase retrieval using a rotating anode x-ray source
Publisher: AIP Publishing
Date: 17-12-2007
DOI: 10.1063/1.2825426
Abstract: We have performed an analyzer crystal based phase contrast imaging (ABI) experiment using a rotating anode x-ray source. The use of such an incoherent source demonstrates the potential of ABI as a quantitative characterization tool for the laboratory environment. A phase contrast image of a plastic phantom was recorded on high resolution x-ray film and the projected thickness was retrieved from a single image. The projected thickness recovered from the phase contrast image was shown to quantitatively agree with a reference optical microscope measurement.
High resolution x-ray diffractometry of the structural characteristics of a semiconducting (InGa)As/GaAs superlattice
Publisher: Pleiades Publishing Ltd
Date: 02-1999
DOI: 10.1134/1.1259279
Dynamic studies of lung fluid clearance with phase contrast imaging
Publisher: AIP
Date: 2007
DOI: 10.1063/1.2436444
InAs/GaSb superlattices characterized by high resolution X-ray diffraction and infrared optical spectroscopy
Publisher: SPIE
Date: 09-1995
DOI: 10.1117/12.218204
Phase retrieval using radiation and matter-wave fields: Validity of Teague's method for solution of the transport-of-intensity equation
Publisher: American Physical Society (APS)
Date: 08-08-2011
Applications of dynamical theory of X-ray diffraction by perfect crystals to reciprocal space mapping
Publisher: International Union of Crystallography (IUCr)
Date: 09-08-2017
DOI: 10.1107/S1600576717010123
Abstract: The classical dynamical theory of X-ray diffraction is expanded to the special case of transversely restricted wavefronts of the incident and reflected waves. This approach allows one to simulate the two-dimensional coherently scattered intensity distribution centred around a particular reciprocal lattice vector in the so-called triple-crystal diffraction scheme. The effect of the diffractometer's instrumental function on X-ray diffraction data was studied.
Absorption edge subtraction imaging for volumetric measurement in an animal model of malignant brain tumor
Publisher: Elsevier BV
Date: 08-2005
Simple method for estimating linear attenuation coefficients from x-ray diffraction tomography data
Publisher: AIP Publishing
Date: 03-2001
DOI: 10.1063/1.1344171
Abstract: In this article, we demonstrate how the spatial distribution of x-ray linear attenuation coefficients within an object can be estimated from x-ray diffraction tomography data. The experimental arrangement to achieve this exploits a position sensitive detector and an analyzer crystal. The quality of reconstructed maps of linear attenuation coefficients is comparable to results obtained from conventional transmission computed tomography.
High-resolution X-ray diffractometry investigation of interface layers in GaN/AlN structures grown on sapphire substrates
Publisher: World Scientific Pub Co Pte Lt
Date: 04-2003
DOI: 10.1142/S0218625X03005001
Abstract: GaInN is an important wide band gap material with applications in short wavelength optoelectronic devices. The GaInN layer is often grown on a sapphire substrate, with low-temperature-deposited AlN and thick GaN used as buffer layers. The growth regime consists of many steps, each of which contributes to the overall properties of the device. The aim of our high-resolution X-ray diffraction experiments, conducted at the Photon Factory (Tsukuba, Japan), was to investigate the structural quality of the AlN buffer layer, which affects the final properties of the device. Reciprocal space mapping was used to study s les (having various layer thicknesses) from each stage of the growth process. Analysis of the experimental data provides parameters such as mosaic block dimensions and orientation, lattice strain distribution, and layer thickness.
Quantized hard-x-ray phase vortices nucleated by aberrated nanolenses
Publisher: American Physical Society (APS)
Date: 14-01-2011
Linear systems with slowly varying transfer functions and their application to X-ray phase-contrast imaging
Publisher: IOP Publishing
Date: 16-09-2004
Phase contrast X-ray imaging of mice and rabbit lungs: A comparative study
Publisher: British Institute of Radiology
Date: 11-2005
DOI: 10.1259/BJR/13024611
Abstract: The significant degree of X-ray phase contrast created by air-tissue interfaces, coupled with the poor radiographic contrast of conventional chest radiographs, makes the inflated lung an ideal candidate for investigating the potential diagnostic improvement afforded by phase contrast X-ray imaging. In small animals these methods highlight the lung airways and lobe boundaries and reveal the lung tissue as a speckled intensity pattern not seen in other soft tissues. We have compared analyser-based and propagation-based phase contrast imaging modalities, together with conventional radiographic imaging, to ascertain which technique shows the greatest image enhancement for various lung sizes. The conventional radiographic image of a mouse was obtained on a Siemens Nova 3000 mammography system, whilst phase contrast images of mice and rabbit chests were acquired at the medical imaging beamline (20B2) at the SPring-8 synchrotron radiation research facility in Japan. For mice aged 1 day, 1 week and 1 month old it was determined that analyser-based imaging showed the greatest overall image contrast, however, for an adult rabbit both techniques yielded excellent contrast. The success of these methods in creating high quality images for rabbit lungs raises the possibility of improving human lung imaging using phase contrast techniques.
Fast three-dimensional phase retrieval in propagation-based X-ray tomography.
Publisher: International Union of Crystallography (IUCr)
Date: 02-04-2019
DOI: 10.1107/S1600577519002133
Abstract: The following article describes a method for 3D reconstruction of multi-material objects based on propagation-based X-ray phase-contrast tomography (PB-CT) with phase retrieval using the homogeneous form of the transport of intensity equation (TIE-Hom). Unlike conventional PB-CT algorithms that perform phase retrieval of in idual projections, the described post-reconstruction phase-retrieval method is applied in 3D to a localized region of the CT-reconstructed volume. This work demonstrates, via numerical simulations, the accuracy and noise characteristics of the method under a variety of experimental conditions, comparing it with both conventional absorption tomography and 2D TIE-Hom phase retrieval applied to projection images. The results indicate that the 3D post-reconstruction method generally achieves a modest improvement in noise suppression over existing PB-CT methods. It is also shown that potentially large computational gains over projection-based phase retrieval for multi-material s les are possible. In particular, constraining phase retrieval to a localized 3D region of interest reduces the overall computational cost and eliminates the need for multiple CT reconstructions and global 2D phase retrieval operations for each material within the s le.
Influence of Long-Range Lateral Ordering in Structures with Quantum Dots on the Spatial Distribution of Diffracted X-Ray Radiation
Publisher: IOP Publishing
Date: 02-1999
DOI: 10.1143/JJAP.38.818
Abstract: Perfectly crystalline (InAs–GaAs) multilayer periodic structures on (001) GaAs, which contain InAs quantum dots (QDs), have been studied by high-resolution X-ray diffraction. It has been shown that the existence of such scattering objects as QDs strongly influences X-ray diffraction, changing the spatial distribution of scattered radiation. Additional long-range ordering in layers containing QDs results in unusual and significant elongation of superlattice and substrate reflections in the q x direction. A novel qualitative model of scattering layers consisting of perfect InAs and GaAs coherent clusters has been developed.
Single-Shot X-Ray Speckle-Based Imaging of a Single-Material Object
Publisher: American Physical Society (APS)
Date: 11-05-2020
The equations of the statistical dynamical theory of x-ray diffraction for deformed crystals (vol 54, pg 214, 1998)
Publisher: International Union of Crystallography (IUCr)
Date: 07-1998
Phase contrast image segmentation using a Laue analyser crystal
Publisher: IOP Publishing
Date: 06-01-2011
DOI: 10.1088/0031-9155/56/3/001
Abstract: Dual-energy x-ray imaging is a powerful tool enabling two-component s les to be separated into their constituent objects from two-dimensional images. Phase contrast x-ray imaging can render the boundaries between media of differing refractive indices visible, despite them having similar attenuation properties this is important for imaging biological soft tissues. We have used a Laue analyser crystal and a monochromatic x-ray source to combine the benefits of both techniques. The Laue analyser creates two distinct phase contrast images that can be simultaneously acquired on a high-resolution detector. These images can be combined to separate the effects of x-ray phase, absorption and scattering and, using the known complex refractive indices of the s le, to quantitatively segment its component materials. We have successfully validated this phase contrast image segmentation (PCIS) using a two-component phantom, containing an iodinated contrast agent, and have also separated the lungs and ribcage in images of a mouse thorax. Simultaneous image acquisition has enabled us to perform functional segmentation of the mouse thorax throughout the respiratory cycle during mechanical ventilation.
Analysis of the mosaic structure of an ordered (Al,Ga)N layer
Publisher: International Union of Crystallography (IUCr)
Date: 19-01-2005
DOI: 10.1107/S0021889804030675
Abstract: The mosaic structure of an (Al,Ga)N layer grown on (0001) sapphire showing natural ordering was studied by high-resolution X-ray diffraction (HRXRD) reciprocal-space mapping. The direction-dependent mosaicity of the layer has been elaborated using maps of symmetrical and asymmetrical reflections. The reciprocal-lattice points show significant broadening depending on the direction in reciprocal space, the diffraction order and the reflection type (fundamental or superstructural). The evaluation followed two paths: (i) a procedure based on the Williamson–Hall plot and (ii) a new approach based on the statistical diffraction theory (SDT). Here, the transformed Takagi equations were implemented for the simulation of the reciprocal-space maps (RSM) for symmetrical and asymmetrical reflections. The reconstruction comprised the mosaic block size, their average rotation angle and the spatial distribution of some components of the microdistortion tensor. The results based on the SDT modelling agree well with those obtained by the Williamson–Hall method, while providing a higher degree of precision and detail.
A variant on the geometrical optics approximation in diffraction enhanced tomography
Publisher: IOP Publishing
Date: 03-05-2001
Quantitative diffraction-enhanced x-ray imaging of weak objects
Publisher: IOP Publishing
Date: 31-03-2004
Collection of reciprocal space maps using imaging plates at the Australian National Beamline Facility at the Photon Factory
Publisher: International Union of Crystallography (IUCr)
Date: 17-08-2004
Tomographic reconstruction using tilted Laue analyser-based X-ray phase-contrast imaging
Publisher: International Union of Crystallography (IUCr)
Date: 2021
DOI: 10.1107/S1600577520013995
Abstract: Analyser-based phase-contrast imaging (ABPCI) is a highly sensitive phase-contrast imaging method that produces high-contrast images of weakly absorbing materials. However, it is only sensitive to phase gradient components lying in the diffraction plane of the analyser crystal [ i.e. in one dimension (1-D)]. In order to accurately account for and measure phase effects produced by the wavefield-s le interaction, ABPCI and other 1-D phase-sensitive methods must achieve 2-D phase gradient sensitivity. An inclined geometry method was applied to a Laue geometry setup for X-ray ABPCI through rotation of the detector and object about the optical axis. This allowed this traditionally 1-D phase-sensitive phase-contrast method to possess 2-D phase gradient sensitivity. Tomographic datasets were acquired over 360° of a multi-material phantom with the detector and s le tilted by 8°. The real and imaginary parts of the refractive index were reconstructed for the phantom.
Speckle-Based X-Ray Dark-Field Tomography of an Attenuating Object
Publisher: SPIE
Date: 09-09-2021
DOI: 10.1117/12.2597722
Calculating X-ray diffraiction from multilayer lateral crystal structures with arbitrary shapes and composition profiles
Publisher: Pleiades Publishing Ltd
Date: 02-2007
A feasibility study of X-ray phase-contrast mammographic tomography at the Imaging and Medical beamline of the Australian Synchrotron
Publisher: International Union of Crystallography (IUCr)
Date: 16-10-2015
DOI: 10.1107/S160057751501766X
Abstract: Results are presented of a recent experiment at the Imaging and Medical beamline of the Australian Synchrotron intended to contribute to the implementation of low-dose high-sensitivity three-dimensional mammographic phase-contrast imaging, initially at synchrotrons and subsequently in hospitals and medical imaging clinics. The effect of such imaging parameters as X-ray energy, source size, detector resolution, s le-to-detector distance, scanning and data processing strategies in the case of propagation-based phase-contrast computed tomography (CT) have been tested, quantified, evaluated and optimized using a plastic phantom simulating relevant breast-tissue characteristics. Analysis of the data collected using a Hamamatsu CMOS Flat Panel Sensor, with a pixel size of 100 µm, revealed the presence of propagation-based phase contrast and demonstrated significant improvement of the quality of phase-contrast CT imaging compared with conventional (absorption-based) CT, at medically acceptable radiation doses.
An improvement to the diffraction-enhanced imaging method that permits imaging of dynamic systems
Publisher: Elsevier BV
Date: 08-2005
Unification of analyser-based and propagation-based X-ray phase-contrast imaging
Publisher: Elsevier BV
Date: 08-2005
Bragg-Laue X-ray dynamical diffraction on perfect and deformed lateral crystalline structures
Publisher: International Union of Crystallography (IUCr)
Date: 06-07-2016
DOI: 10.1107/S1600576716008396
Abstract: The new dynamical diffraction approach to X-ray diffraction on lateral crystalline structures has been developed to investigate the angular and spatial distribution of wavefields in the case of the Bragg–Laue geometry in non-perfect lateral structures. This approach allows one to calculate reciprocal space maps for deformed lateral crystals having rectangular cross sections for both the transmitted and reflected wavefields. Numerical modelling is performed for crystals with different lateral sizes, thicknesses and deformations. The approach can be used in coherent diffraction imaging to simulate Fraunhofer diffraction patterns produced by relatively large deformed crystals.
X-ray Bragg magnifier microscope as a linear shift invariant imaging system: Image formation and phase retrieval
Publisher: The Optical Society
Date: 28-08-2014
DOI: 10.1364/OE.22.021508
Statistical dynamical theory of X-ray diffraction in the Bragg case: application to triple-crystal diffractometry
Publisher: International Union of Crystallography (IUCr)
Date: 05-2000
DOI: 10.1107/S0108767399016694
Abstract: The statistical dynamical theory of X-ray diffraction is developed for a crystal containing statistically distributed microdefects. Fourier-component equations for coherent and diffuse (incoherent) scattered waves have been obtained in the case of so-called triple-crystal diffractometry. New correlation lengths and areas are introduced for characterization of the scattered volume.
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Related Funding Activities
Discovery Projects - Grant ID: DP0556492
Start Date: 2006
End Date: 05-2009
Amount: $390,000.00
Funder: Australian Research Council
View Funded ActivityDiscovery Projects - Grant ID: DP0556840
Start Date: 10-2005
End Date: 04-2009
Amount: $240,000.00
Funder: Australian Research Council
View Funded ActivitySpecial Research Initiatives - Grant ID: SR120200004
Start Date: 07-2012
End Date: 12-2015
Amount: $30,000,000.00
Funder: Australian Research Council
View Funded Activity