ORCID Profile
0000-0002-7333-5472
Current Organisations
UCL Institute of Education
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CSIRO
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Condensed Matter Physics | Nanoscale Characterisation | Condensed Matter Imaging | Condensed Matter Characterisation Technique Development |
Expanding Knowledge in the Chemical Sciences | Expanding Knowledge in the Physical Sciences | Expanding Knowledge in Technology
Publisher: Optica Publishing Group
Date: 22-09-2003
DOI: 10.1364/OE.11.002289
Abstract: In-line phase contrast enables weakly absorbing specimens to be imaged successfully with x-rays, and greatly enhances the visibility of fine scale structure in more strongly absorbing specimens. This type of phase contrast requires a spatially coherent beam, a condition that can be met by a microfocus x-ray source. We have developed an x-ray microscope, based on such a source, which is capable of high resolution phase-contrast imaging and tomography. Phase retrieval enables quantitative information to be recovered from phase-contrast microscope images of homogeneous s les of known composition and density, and improves the quality of tomographic reconstructions.
Publisher: Wiley
Date: 04-2002
DOI: 10.1046/J.1365-2818.2002.01010.X
Abstract: We demonstrate simultaneous phase and litude extraction from a single defocused image of a homogeneous object. Subject to the assumptions explicitly stated in the derivation, the algorithm solves the twin-image problem of in-line holography and is capable of analysing data obtained using X-ray microscopy, electron microscopy, neutron microscopy or visible-light microscopy, especially as they relate to defocus and point projection methods. Our simple, robust, non-iterative and computationally efficient method is applied to data obtained using an X-ray phase contrast ultramicroscope.
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.
Publisher: Optica Publishing Group
Date: 20-04-2004
DOI: 10.1364/AO.43.002418
Abstract: The first Born and Rytov approximations of scattering theory are introduced in their less familiar near-field versions. Two algorithms for phase retrieval based on these approximations are then described. It is shown theoretically and by numerical simulations that, despite the differences in their formulation, the two algorithms deliver fairly similar results when used for optical phase retrieval in the near and intermediate fields. The algorithms are applied to derive explicit solutions to four phase-retrieval problems of practical relevance to quantitative phase-contrast imaging and tomography. An ex le of successful phase reconstruction by use of the Born-type algorithm with an experimental x-ray image is presented.
Publisher: International Union of Crystallography (IUCr)
Date: 12-1994
Publisher: IOP Publishing
Date: 24-02-2017
Abstract: The aim of this study was to optimise the experimental protocol and data analysis for in-vivo breast cancer x-ray imaging. Results are presented of the experiment at the SYRMEP beamline of Elettra Synchrotron using the propagation-based phase-contrast mammographic tomography method, which incorporates not only absorption, but also x-ray phase information. In this study the images of breast tissue s les, of a size corresponding to a full human breast, with radiologically acceptable x-ray doses were obtained, and the degree of improvement of the image quality (from the diagnostic point of view) achievable using propagation-based phase-contrast image acquisition protocols with proper incorporation of x-ray phase retrieval into the reconstruction pipeline was investigated. Parameters such as the x-ray energy, s le-to-detector distance and data processing methods were tested, evaluated and optimized with respect to the estimated diagnostic value using a mastectomy s le with a malignant lesion. The results of quantitative evaluation of images were obtained by means of radiological assessment carried out by 13 experienced specialists. A comparative analysis was performed between the x-ray and the histological images of the specimen. The results of the analysis indicate that, within the investigated range of parameters, both the objective image quality characteristics and the subjective radiological scores of propagation-based phase-contrast images of breast tissues monotonically increase with the strength of phase contrast which in turn is directly proportional to the product of the radiation wavelength and the s le-to-detector distance. The outcomes of this study serve to define the practical imaging conditions and the CT reconstruction procedures appropriate for low-dose phase-contrast mammographic imaging of live patients at specially designed synchrotron beamlines.
Publisher: IOP Publishing
Date: 20-08-2014
Publisher: Wiley
Date: 22-05-2012
Publisher: International Union of Crystallography (IUCr)
Date: 11-07-2012
Publisher: Springer International Publishing
Date: 2018
Publisher: American Physical Society (APS)
Date: 24-10-2007
Publisher: AIP Publishing
Date: 15-05-2009
DOI: 10.1063/1.3115402
Abstract: Absorption-contrast x-ray imaging serves to visualize the variation in x-ray attenuation within the volume of a given s le, whereas phase contrast allows one to visualize variations in x-ray refractive index. The former imaging mechanism has been well known and widely utilized since the time of Röntgen’s Nobel prize winning work, whereas the latter mechanism—sought for, but not found, by Röntgen himself—has laid the foundation for a revolution in x-ray imaging which is the central topic of this review. We consider the physical imaging mechanisms underlying both absorption contrast and phase contrast, together with the associated inverse problem of how one may obtain quantitative two- or three-dimensional information regarding a s le, given one or more phase-contrast images of the same. Practical questions are considered, regarding optimized phase-contrast imaging geometries as a function of detector resolution, source size, x-ray spectrum, and dose. Experimental ex les pertaining to biomedical applications are given, and prospects for the future outlined.
Publisher: Wiley
Date: 31-03-2017
Publisher: EAGE Publications BV
Date: 23-05-2011
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.
Publisher: SAGE Publications
Date: 25-02-2023
DOI: 10.1177/15327086231154308
Abstract: In this “paper,” we share our process of exploring the possibilities for the emergence of new ways of knowing-thinking-doing response-able collaboration. In an effort to come “together-apart” as author-collaborators, working from our different positionings and locations in the world, we shared text and images of the various ways the ideas from in idual papers (nodal points) and our diffractive processes were moving (with) us. Sharing these creative respondings, new relations co-emerged through the texts-images and the various diffractive patterns that traveled widely through screens, devices, bodies, from New Zealand and Australia, to Iran, London, Finland, Canada, and the West and East Coasts of the United States. Paying attention to the fine details, difference emerged, as did new forms of more-than-human connection. The visual and written respondings were then cut together-apart (literally, metaphorically and methodologically) to represent the multiplicities of the diffractive process, bodies, hauntings, absences and excess, and the tensions and affective vulnerabilities that co-emerged through our process. We present four visual montages of the diffractive patterns that surfaced from the in idual papers as nodal points and our creative collaborative processes of becoming-with the special issue. We conclude with some final thoughts on the process of diffracting the special issue, inviting the reader to join us in imagining new lines of flight, alternative possibilities for becoming a more response-able, more-than-human academic community.
Publisher: SAGE Publications
Date: 04-0002
DOI: 10.1177/15327086231154307
Abstract: In this article, we share a curated version of a Zoom meeting in which we come together-apart to articulate our experiences of the diffractive review process. In the later part of the dialogue, we turn toward imagining the possibilities for creatively exploring ways to represent how the ideas from this collaborative process travel with us, into our everyday lives. We discuss the ethical and political response-abilities in such diffractive collaboration and respondings, and in so doing, different author perspectives, positionalities, and productive tensions and knots, come to the fore. In so doing, this article connects the first part of the issue—the nodal points (author manuscripts)—with the final part of the issue (diffractive respondings), and provides insight into our collaborative and diffractive process.
Publisher: Trans Tech Publications, Ltd.
Date: 06-2010
DOI: 10.4028/WWW.SCIENTIFIC.NET/MSF.654-656.2322
Abstract: X-ray phase-contrast imaging and tomography add an additional dimension to conventional x-ray methods by exploiting the x-ray refraction effects in addition to x-ray absorption in forming an image. This greatly enhances the visibility of edges, voids and boundaries within a s le. It also makes it possible to characterise weakly x-ray absorbing s les which would produce little or no contrast in conventional x-ray imaging. Here we described the application of a laboratory-based x-ray phase-contrast microscope to x-ray micro-tomography of a self-healing polymer system and the quantitative analysis of the resulting three dimensional (3D) datasets to better understand the healing and ageing processes.
Publisher: International Union of Crystallography (IUCr)
Date: 04-1998
Publisher: Public Library of Science (PLoS)
Date: 29-02-2012
Publisher: Springer International Publishing
Date: 2016
Publisher: International Union of Crystallography (IUCr)
Date: 08-1996
Publisher: Elsevier BV
Date: 11-2020
DOI: 10.1016/J.HEALUN.2020.07.015
Abstract: Driveline infections remain a major complication of ventricular assist device (VAD) implantation. This study aimed to characterize in vivo microbial biofilms associated with driveline infections and host tissue integration of implanted drivelines. A total of 9 infected and 13 uninfected drivelines were obtained from patients with VAD undergoing heart transplantation in Australia between 2016 and 2018. Each driveline was sectioned into 11 pieces of 1.5 cm in length, and each section was examined by scanning electron microscopy (SEM) and viable counts for microbial biofilms. Microorganisms were cultured and identified. Host tissue integration of clinical drivelines was assessed with micro-computed tomography (CT) and SEM. An in vitro interstitial biofilm assay was used to simulate biofilm migration in the driveline tunnel, and time-lapse microscopy was performed. Of the 9 explanted, infected drivelines, all had organisms isolated from varying depths along the velour section of the drivelines, and all were consistent with the swab culture results of the clinically infected exit site. SEM and micro-CT suggested insufficient tissue integration throughout the driveline velour, with microgaps observed. Clinical biofilms presented as microcolonies within the driveline tunnel, with human tissue as the sub-stratum, and were resistant to anti-microbial treatment. Biofilm migration mediated by a dispersal-seeding mechanism was observed. This study of explanted infected drivelines showed extensive anti-microbial-resistant biofilms along the velour, associated with microgaps between the driveline and the surrounding tissue. These data support the enhancement of tissue integration into the velour as a potential preventive strategy against driveline infections by preventing biofilm migration that may use microgaps as mediators.
Publisher: IOP Publishing
Date: 09-2009
Publisher: SPIE-Intl Soc Optical Eng
Date: 12-07-2021
Publisher: AIP Publishing LLC
Date: 2016
DOI: 10.1063/1.4937500
Publisher: International Union of Crystallography (IUCr)
Date: 08-1992
Publisher: Springer Science and Business Media LLC
Date: 30-04-2011
DOI: 10.1007/S00216-011-4978-3
Abstract: X-ray fluorescence microscopy (XFM) facilitates high-sensitivity quantitative imaging of trace metals at high spatial resolution over large s le areas and can be applied to a erse range of biological s les. Accurate determination of elemental content from recorded spectra requires proper calibration of the XFM instrument under the relevant operating conditions. Here, we describe the manufacture, characterization, and utilization of multi-element thin-film reference foils for use in calibration of XFM measurements of biological and other specimens. We have used these internal standards to assess the two-dimensional distribution of trace metals in a thin tissue section of a rat hippoc us. The data used in this study was acquired at the XFM beamline of the Australian Synchrotron using a new 384-element array detector (Maia) and at beamline 2-ID-E at the Advanced Photon Source. Post-processing of s les by different fixation techniques was investigated, with the conclusion that differences in solvent type and s le handling can significantly alter elemental content. The present study highlights the quantitative capability, high statistical power, and versatility of the XFM technique for mapping trace metals in biological s les, e.g., brain tissue s les in order to help understand neurological processes, especially when implemented in conjunction with a high-performance detector such as Maia.
Publisher: Optica Publishing Group
Date: 15-04-2004
DOI: 10.1364/OL.29.000866
Abstract: We report an alternative approach to x-ray wave-front analysis that uses a refractive microlens array as a Shack-Hartmann sensor. The sensor was manufactured by self-assembly and electroplating techniques and is suitable for high-resolution wave-front analysis of medium to hard x rays. We demonstrate its effectiveness at an x-ray energy of 3 keV for analysis of x-ray wave-front perturbations caused by microscopic objects. The sensor has potential advantages over other methods for x-ray phase imaging and will also be useful for the characterization of x-ray beams and optics.
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.
Publisher: Elsevier BV
Date: 08-2012
Publisher: International Union of Crystallography (IUCr)
Date: 06-1999
DOI: 10.1107/S0021889898018470
Abstract: A recently developed method for fitting a Monte Carlo computer simulation model to observed single-crystal diffuse X-ray scattering has been applied to ( hk 0) scattering data obtained for the guest–host system (inclusion compound) cyclohexane–perhydrotriphenylene (cyclohexane–PHTP), C 6 H 12 /C 18 H 30 , at 295 K. A simple two-dimensional model representing the projection of the structure down c was used, which allowed refinement of short-range order parameters describing the mutual orientation of guest molecules within neighbouring channels, together with a parameter describing the coupling of these orientations to distortions of the host framework. Since the guest site still appears very disordered in projection, only a crude model for the shape of the guest molecule was used. The resulting calculated diffraction patterns showed good qualitative agreement with the observed pattern, but quantitatively the achieved agreement factor ( R ≃ 38%) was considerably higher than that achieved in comparable studies of a different system. Calculations of the contribution to the diffraction pattern of the guest alone and the host alone clearly indicate that the host framework distortion is modelled well, but the guest is not so well described. The lattice distortion revealed by the study indicates a tendency for the hexagonal network to distort towards local monoclinicity. This is consistent with the observation that at ~273 K, the compound undergoes a reversible phase transition to a micro-twinned monoclinic phase.
Publisher: EAGE Publications BV
Date: 2013
Publisher: Oxford University Press (OUP)
Date: 31-07-2006
DOI: 10.1017/S1431927606067420
Abstract: Extended abstract of a paper presented at Microscopy and Microanalysis 2006 in Chicago, Illinois, USA, July 30 – August 3, 2005
Publisher: International Union of Crystallography (IUCr)
Date: 12-2010
Publisher: Oxford University Press (OUP)
Date: 08-2004
DOI: 10.1017/S1431927604880279
Abstract: Extended abstract of a paper presented at Microscopy and Microanalysis 2004 in Savannah, Georgia, USA, August 1–5, 2004.
Publisher: Springer Science and Business Media LLC
Date: 30-06-2016
Publisher: Elsevier BV
Date: 2008
Publisher: Elsevier BV
Date: 07-2010
Publisher: Optica Publishing Group
Date: 02-07-2008
DOI: 10.1364/OE.16.010736
Abstract: In X-ray computed tomography (CT) increased information requirements (e.g. increased resolution) typically lead to a concurrent increase in the required number of viewing angles, scanning time and delivered dose. We demonstrate that using phase-contrast imaging it is possible to "dissect" two- and three-material objects into their component materials, which in combination with binary tomographic techniques allows us to satisfy increased information requirements without taking the usual images at additional viewing angles. This imaging scheme reduces the scanning time and dose delivered to s les by at least an order of magnitude when compared to conventional X-ray CT. The effects of noise on our reconstruction scheme are investigated for simulated data. Finally, a slice through a glass tube filled with silica and water is reconstructed from 18 projection images taken on an X-ray ultra Microscope (XuM).
Publisher: International Union of Crystallography (IUCr)
Date: 18-03-2014
DOI: 10.1107/S1600577514002793
Abstract: Quantifying three-dimensional spatial distributions of pores and material compositions in s les is a key materials characterization challenge, particularly in s les where compositions are distributed across a range of length scales, and where such compositions have similar X-ray absorption properties, such as in coal. Consequently, obtaining detailed information within sub-regions of a multi-length-scale s le by conventional approaches may not provide the resolution and level of detail one might desire. Herein, an approach for quantitative high-definition determination of material compositions from X-ray local computed tomography combined with a data-constrained modelling method is proposed. The approach is capable of dramatically improving the spatial resolution and enabling finer details within a region of interest of a s le larger than the field of view to be revealed than by using conventional techniques. A coal s le containing distributions of porosity and several mineral compositions is employed to demonstrate the approach. The optimal experimental parameters are pre-analyzed. The quantitative results demonstrated that the approach can reveal significantly finer details of compositional distributions in the s le region of interest. The elevated spatial resolution is crucial for coal-bed methane reservoir evaluation and understanding the transformation of the minerals during coal processing. The method is generic and can be applied for three-dimensional compositional characterization of other materials.
Publisher: International Union of Crystallography (IUCr)
Date: 08-1992
Publisher: Wiley
Date: 08-2002
DOI: 10.1046/J.1365-2818.2002.01046.X
Abstract: We outline a new approach to X-ray projection microscopy in a scanning electron microscope (SEM), which exploits phase contrast to boost the quality and information content of images. These developments have been made possible by the combination of a high-brightness field-emission gun (FEG)-based SEM, direct detection CCD technology and new phase retrieval algorithms. Using this approach we have been able to obtain spatial resolution of < 0.2 micro m and have demonstrated novel features such as: (i) phase-contrast enhanced visibility of high spatial frequency image features (e.g. edges and boundaries) over a wide energy range (ii) energy-resolved imaging to simultaneously produce multiple quasi-monochromatic images using broad-band polychromatic illumination (iii) easy implementation of microtomography (iv) rapid and robust phase/ litude-retrieval algorithms to enable new real-time and quantitative modes of microscopic imaging. These algorithms can also be applied successfully to recover object-plane information from intermediate-field images, unlocking the potentially greater contrast and resolution of the intermediate-field regime. Widespread applications are envisaged for fields such as materials science, biological and biomedical research and microelectronics device inspection. Some illustrative ex les are presented. The quantitative methods described here are also very relevant to projection microscopy using other sources of radiation, such as visible light and electrons.
Publisher: Elsevier BV
Date: 12-2007
Publisher: IOP Publishing
Date: 11-2012
DOI: 10.1088/0022-3727/45/47/475103
Abstract: The three-dimensional distribution of the materials composing a s le is reconstructed using multiple-energy computed tomography techniques. The a priori knowledge about the specific materials that are present in the s le is used for decomposing the measured intensity projections into projected thicknesses of each component material. Those decomposed projections are then processed using iterative reconstruction algorithms to separately obtain the three-dimensional distribution of each material. A new iterative reconstruction algorithm has been implemented and its performance is compared to the standard filtered back projection and to another existing iterative algorithm based on histogram manipulation. The method is first tested with simulations on data for a realistic, three-materials' numerical s le and then applied to experimental micro-tomography data. The accuracy of the reconstruction from experimental data is tested by means of an energy dispersive x-ray spectroscopy scan of the s le.
Publisher: International Union of Crystallography (IUCr)
Date: 15-03-1994
Publisher: EDP Sciences
Date: 03-2003
DOI: 10.1051/JP4:20030140
Publisher: Springer Science and Business Media LLC
Date: 05-2000
DOI: 10.1007/BF03167641
Publisher: Wiley
Date: 27-11-2007
DOI: 10.1111/J.1365-2818.2007.01857.X
Abstract: Improved X-ray sources and optics now enable X-ray imaging resolution down to approximately 50 nm for laboratory-based X-ray microscopy systems. This offers the potential for submicrometre resolution in tomography however, achieving this resolution presents challenges due to system stability. We describe the use of software methods to enable submicrometre resolution of approximately 560 nm. This is a very high resolution for a modest laboratory-based point-projection X-ray tomography system. The hardware is based on a scanning electron microscope, and benefits from inline X-ray phase contrast to improve visibility of fine features. Improving the resolution achievable with the system enables it to be used to address a greater range of s les.
Publisher: SPIE
Date: 04-04-2022
DOI: 10.1117/12.2608596
Publisher: SPIE
Date: 31-08-2006
DOI: 10.1117/12.680154
Publisher: AIP
Date: 2004
DOI: 10.1063/1.1757813
Publisher: IOP Publishing
Date: 25-10-2013
Publisher: Elsevier BV
Date: 05-2013
Publisher: SPIE-Intl Soc Optical Eng
Date: 07-02-2022
Publisher: Elsevier BV
Date: 2021
Publisher: Wiley
Date: 21-05-2004
Publisher: Inderscience Publishers
Date: 2013
Publisher: Elsevier BV
Date: 12-2021
Publisher: Institute of Electrical and Electronics Engineers (IEEE)
Date: 12-2018
Publisher: Elsevier BV
Date: 2017
Publisher: AIP
Date: 2007
DOI: 10.1063/1.2723616
Publisher: Institute of Electrical and Electronics Engineers (IEEE)
Date: 11-2022
Publisher: Elsevier BV
Date: 08-2010
DOI: 10.1016/J.JSB.2010.04.001
Abstract: The structure of wood on a range of length-scales is critical to the performance and properties of this industrially important natural material. Much analysis of wood on the micron-scale upwards is carried out in two dimensions using optical microscopy. In recent years, however, three-dimensional (3D) analysis using X-ray microtomography has proved to be of increasing interest, providing volumetric data without the risk of damage from physical sectioning. In the present work we explore the potential of laboratory-based phase-contrast X-ray microtomography for analysis of wood microstructure on the micron scale. 3D datasets with quality enhanced by the use of phase-contrast, have been obtained for a number of different wood specimens. Segmentation of the datasets followed by different types of quantitative analysis is also successfully demonstrated, confirming the value of this technique for high-resolution analysis of 3D wood microstructure.
Publisher: Wiley
Date: 20-10-2019
DOI: 10.1002/MP.13842
Abstract: Propagation-based phase-contrast computed tomography (PB-CT) is a method for three-dimensional x-ray imaging that utilizes refraction, as well as absorption, of x rays in the tissues to increase the signal-to-noise ratio (SNR) in the resultant images, in comparison with equivalent conventional absorption-only x-ray tomography (CT). Importantly, the higher SNR is achieved without sacrificing spatial resolution or increasing the radiation dose delivered to the imaged tissues. The present work has been carried out in the context of the current development of a breast CT imaging facility at the Australian Synchrotron. Seven unfixed complete mastectomy s les with and without breast cancer lesions have been imaged using absorption-only CT and PB-CT techniques under controlled experimental conditions. The radiation doses delivered to the mastectomy s les during the scans were comparable to those approved for mammographic screening. Physical characteristics of the reconstructed images, such as spatial resolution and SNR, have been measured and compared with the results of the radiological quality assessment of the complete absorption CT and PB-CT image stacks. Despite the presence of some image artefacts, the PB-CT images have outperformed comparable absorption CT images collected at the same radiation dose, in terms of both the measured objective image characteristics and the radiological image scores. The outcomes of these experiments are shown to be consistent with predictions of the theory of PB-CT imaging and previous reported experimental studies of this imaging modality. The results presented in this paper demonstrate that PB-CT holds a high potential for improving on the quality and diagnostic value of images obtained using existing medical x-ray technologies, such as mammography and digital breast tomosynthesis (DBT). If implemented at suitable synchrotron imaging facilities, PB-CT can be used to complement existing imaging modalities, leading to more accurate breast cancer diagnosis.
Publisher: IEEE
Date: 12-2011
DOI: 10.1109/UCC.2011.64
Publisher: International Union of Crystallography (IUCr)
Date: 18-06-2016
DOI: 10.1107/S1600577516008018
Abstract: Synchrotron X-ray tomography (SXRT) has been applied to the study of defects within three-dimensional printed titanium parts. These parts were made using the Arcam EBM ® (electron beam melting) process which uses powdered titanium alloy, Ti64 (Ti alloy with approximately 6%Al and 4%V) as the feed and an electron beam for the sintering/welding. The experiment was conducted on the Imaging and Medical Beamline of the Australian Synchrotron. The s les represent a selection of complex shapes with a variety of internal morphologies. Inspection via SXRT has revealed a number of defects which may not otherwise have been seen. The location and nature of such defects combined with detailed knowledge of the process conditions can contribute to understanding the interplay between design and manufacturing strategy. This fundamental understanding may subsequently be incorporated into process modelling, prediction of properties and the development of robust methodologies for the production of defect-free parts.
Publisher: Springer Science and Business Media LLC
Date: 23-01-2020
DOI: 10.1007/S00330-019-06567-0
Abstract: To evaluate and compare the image quality of propagation-based phase-contrast computed tomography (PB-CT) using synchrotron radiation and conventional cone-beam breast computed tomography (CBBCT) based on various radiological image quality criteria. Eight excised breast tissue s les of various sizes and containing different lesion types were scanned using PB-CT at a synchrotron facility and using CBBCT at a university-affiliated breast imaging centre. PB-CT scans were performed at two different mean glandular dose (MGD) levels: standard (5.8 mGy) and low (1.5 mGy), for comparison with CBBCT scans at the standard MGD (5.8 mGy). Image quality assessment was carried out using six quality criteria and six independent medical imaging experts in a reading room with mammography workstations. The interobserver agreement between readers was evaluated using intraclass correlation coefficient (ICC), and image quality was compared between the two breast imaging modalities using the area under the visual grading characteristic curve (AUC Interobserver agreement between the readers showed moderate reliability for five image criteria (ICC: ranging from 0.488 to 0.633) and low reliability for one criterion (image noise) (ICC 0.307). For five image quality criteria (overall quality, perceptible contrast, lesion sharpness, normal tissue interfaces, and calcification visibility), both standard-dose PB-CT images (AUC Synchrotron-based PB-CT can achieve a significantly higher radiological image quality at a substantially lower radiation dose compared with conventional CBBCT. • PB-CT using synchrotron radiation results in higher image quality than conventional CBBCT for breast imaging. • PB-CT using synchrotron radiation requires a lower radiation dose than conventional CBBCT for breast imaging. • PB-CT can help clinicians diagnose patients with breast cancer.
Publisher: American Physical Society (APS)
Date: 18-06-2001
Publisher: Elsevier BV
Date: 09-2019
Publisher: SPIE
Date: 22-05-2020
DOI: 10.1117/12.2564053
Publisher: Optica Publishing Group
Date: 2008
DOI: 10.1364/OE.16.000908
Abstract: A method is presented for quantitative polychromatic cone-beam phase-contrast tomographic imaging of a single-material object from few projections. This algorithm exploits the natural combination of binary tomography with a phase-retrieval method that makes explicit use of the single-material nature of the s le. Such consistent use of a priori knowledge reduces the number of required projections, implying significantly reduced dose and scanning time when compared to existing phase-contrast tomography methods. Reconstructions from simulated data sets are used to investigate the effects of noise and establish a minimum required number of projections. An experimental demonstration is then given, using data from a point-projection X-ray microscope. Here, the complex distribution of refractive index in a s le containing several nylon fibers with diameters between 100 microm and 420 microm is reconstructed at a spatial resolution of approximately 4 microm from 20 polychromatic phase-contrast projection images with a mean photon energy of 8.4 keV.
Publisher: Elsevier BV
Date: 11-2006
Publisher: SPIE
Date: 28-08-2008
DOI: 10.1117/12.795999
Publisher: The Optical Society
Date: 07-04-2014
DOI: 10.1364/OE.22.009087
Publisher: International Union of Crystallography (IUCr)
Date: 17-06-2016
DOI: 10.1107/S1600577516007359
Abstract: Synchrotron X-ray tomography has been applied to the study of titanium parts fabricated by additive manufacturing (AM). The AM method employed here was the Arcam EBM ® (electron beam melting) process which uses powdered titanium alloy, Ti64 (Ti alloy with approximately 6%Al and 4%V), as the feed and an electron beam for the sintering/welding. The experiment was conducted on the Imaging and Medical Beamline of the Australian Synchrotron. S les were chosen to examine the effect of build direction and complexity of design on the surface morphology and final dimensions of the piece.
Publisher: Springer Science and Business Media LLC
Date: 15-03-2011
DOI: 10.1038/NCOMMS1234
Publisher: IOP Publishing
Date: 30-08-2011
Publisher: Elsevier BV
Date: 02-1995
Publisher: Mineralogical Society
Date: 02-1998
Abstract: Hyalotekite, a framework silicate of composition (Ba,Pb,K) 4 (Ca,Y) 2 Si 8 (B,Be) 2 (Si,B) 28 F, is found in relatively high-temperature (⩾ 500°C) Mn skarns at Långban, Sweden, and peralkaline pegmatites at Dara-i-Pioz, Tajikistan. A new paragenesis at Dara-i-Pioz is pegmatite consisting of the Ba borosilicates leucosphenite and tienshanite, as well as caesium kupletskite, aegirine, pyrochlore, microcline and quartz. Hyalotekite has been partially replaced by barylite and danburite. This hyalotekite contains 1.29–1.78 wt.% Y 2 O 3 , equivalent to 0.172–0.238 Y pfu or 8–11% Y on the Ca site its Pb/(Pb+Ba) ratio ranges 0.36–0.44. Electron microprobe F contents of Långban and Dara-i-Pioz hyalotekite range 1.04–1.45 wt.%, consistent with full occupancy of the F site. A new refinement of the structure factor data used in the original structural determination of a Långban hyalotekite resulted in a structural formula, (Pb l.96 Ba l.86 K 0.18 )Ca 2 (B 1.76 Be 0.24 )(Si l.56 B 0.44 )Si 8 O 28 F, consistent with chemical data and all cations with positive-definite thermal parameters, although with a slight excess of positive charge (+57.14 as opposed to the ideal +57.00). An unusual feature of the hyalotekite framework is that 4 of 28 oxygens are non-bridging by merging these 4 oxygens into two, the framework topology of scapolite is obtained. The triclinic symmetry of hyalotekite observed at room temperature is obtained from a hypothetical tetragonal parent structure via a sequence of displacive phase transitions. Some of these transitions are associated with cation ordering, either Pb–Ba ordering in the large cation sites, or B–Be and Si–B ordering on tetrahedral sites. Others are largely displacive but affect the coordination of the large cations (Pb, Ba, K, Ca). High-resolution electron microscopy suggests that the undulatory extinction characteristic of hyalotekite is due to a fine mosaic microstructure. This suggests that at least one of these transitions occurs in nature during cooling, and that it is first order with a large volume change. A diffuse superstructure observed by electron diffraction implies the existence of a further stage of short-range cation ordering which probably involves both (Pb,K)–Ba and (BeSi,BB)–BSi.
Publisher: Elsevier BV
Date: 08-2015
Publisher: The Royal Society
Date: 06-03-2014
Abstract: This review provides a brief overview, albeit from a somewhat personal perspective, of the evolution and key features of various hard X-ray phase-contrast imaging (PCI) methods of current interest in connection with translation to a wide range of imaging applications. Although such methods have already found wide-ranging applications using synchrotron sources, application to dynamic studies in a laboratory/clinical context, for ex le for in vivo imaging, has been slow due to the current limitations in the brilliance of compact laboratory sources and the availability of suitable high-performance X-ray detectors. On the theoretical side, promising new PCI methods are evolving which can record both components of the phase gradient in a single exposure and which can accept a relatively large spectral bandpass. In order to help to identify the most promising paths forward, we make some suggestions as to how the various PCI methods might be compared for performance with a particular view to identifying those which are the most efficient, given the fact that source performance is currently a key limiting factor on the improved performance and applicability of PCI systems, especially in the context of dynamic s le studies. The rapid ongoing development of both suitable improved sources and detectors gives strong encouragement to the view that hard X-ray PCI methods are poised for improved performance and an even wider range of applications in the near future.
Publisher: Oxford University Press (OUP)
Date: 03-05-2012
DOI: 10.1017/S1431927612000323
Abstract: Conventional X-ray microcomputed tomography (micro-CT) is not usually sufficient to determine microscopic compositional distributions as it is limited to measuring the X-ray attenuation of the s le, which for a given dataset can be similar for materials of different composition. In contrast, the present work enables three-dimensional compositional analysis with a data-constrained microstructure (DCM) modeling methodology, which uses two or more CT datasets acquired with different X-ray spectra and incorporates them as model constraints. For providing input data for DCM, we have also developed a method of micro-CT data collection that enables two datasets with different X-ray spectra to be acquired in parallel. Such data are used together with the DCM methodology to predict the distributions of corrosion inhibitor and filler in a polymer matrix. The DCM-predicted compositional microstructures have a reasonable agreement with energy dispersive X-ray images taken on the s le surface.
Publisher: Oxford University Press (OUP)
Date: 08-2018
Publisher: Elsevier BV
Date: 06-2019
DOI: 10.1016/J.ACRA.2018.07.008
Abstract: This study employs clinical/radiological evaluation in establishing the optimum imaging conditions for breast cancer imaging using the X-ray propagation-based phase-contrast tomography. Two series of experiments were conducted and in total 161 synchrotron-based computed tomography (CT) reconstructions of one breast mastectomy specimen were produced at different imaging conditions. Imaging factors include s le-to-detector distance, X-ray energy, CT reconstruction method, phase retrieval algorithm applied to the CT projection images and maximum intensity projection. Observers including breast radiologists and medical imaging experts compared the quality of the reconstructed images with reference images approximating the conventional (absorption) CT. Various radiological image quality attributes in a visual grading analysis design were used for the radiological assessments. The results show that the application of the longest achievable s le-to-detector distance (9.31 m), the lowest employed X-ray energy (32 keV), the full phase retrieval, and the maximum intensity projection can significantly improve the radiological quality of the image. Several combinations of imaging variables resulted in images with very high-quality scores. The results of the present study will support future experimental and clinical attempts to further optimize this innovative approach to breast cancer imaging.
Publisher: American Physical Society (APS)
Date: 05-08-2004
Publisher: Oxford University Press (OUP)
Date: 08-2005
Publisher: Elsevier BV
Date: 2018
Publisher: SPIE
Date: 28-08-2008
DOI: 10.1117/12.794497
Publisher: Elsevier BV
Date: 12-1998
Publisher: Elsevier BV
Date: 08-2018
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.
Publisher: MDPI AG
Date: 03-04-2021
DOI: 10.3390/APP11094120
Abstract: The Imaging and Medical Beamline (IMBL) is a superconducting multipole wiggler-based beamline at the 3 GeV Australian Synchrotron operated by the Australian Nuclear Science and Technology Organisation (ANSTO). The beamline delivers hard X-rays in the 25–120 keV energy range and offers the potential for a range of biomedical X-ray applications, including radiotherapy and medical imaging experiments. One of the imaging modalities available at IMBL is propagation-based X-ray phase-contrast computed tomography (PCT). PCT produces superior results when imaging low-density materials such as soft tissue (e.g., breast mastectomies) and has the potential to be developed into a valuable medical imaging tool. We anticipate that PCT will be utilized for medical breast imaging in the near future with the advantage that it could provide better contrast than conventional X-ray absorption imaging. The unique properties of synchrotron X-ray sources such as high coherence, energy tunability, and high brightness are particularly well-suited for generating PCT data using very short exposure times on the order of less than 1 min. The coherence of synchrotron radiation allows for phase-contrast imaging with superior sensitivity to small differences in soft-tissue density. Here we also compare the results of PCT using two different detectors, as these unique source characteristics need to be complemented with a highly efficient detector. Moreover, the application of phase retrieval for PCT image reconstruction enables the use of noisier images, potentially significantly reducing the total dose received by patients during acquisition. This work is part of ongoing research into innovative tomographic methods aimed at the introduction of 3D X-ray medical imaging at the IMBL to improve the detection and diagnosis of breast cancer. Major progress in this area at the IMBL includes the characterization of a large number of mastectomy s les, both normal and cancerous, which have been scanned at clinically acceptable radiation dose levels and evaluated by expert radiologists with respect to both image quality and cancer diagnosis.
Publisher: SPIE
Date: 19-08-2010
DOI: 10.1117/12.861964
Publisher: Oxford University Press (OUP)
Date: 29-05-2015
DOI: 10.1017/S1431927615000653
Abstract: Data-constrained modeling is a method that enables three-dimensional distribution of mineral phases and porosity in a s le to be modeled based on micro-computed tomography scans acquired at different X-ray energies. Here we describe an alternative method for measuring porosity, synchrotron K-edge subtraction using xenon gas as a contrast agent. Results from both methods applied to the same Darai limestone s le are compared. Reasonable agreement between the two methods and with other porosity measurements is obtained. The possibility of a combination of data-constrained modeling and K-edge subtraction methods for more accurate s le characterization is discussed.
Publisher: EAGE Publications BV
Date: 04-06-2012
Publisher: American Chemical Society (ACS)
Date: 11-11-2013
DOI: 10.1021/NN403118U
Abstract: The usefulness of zinc oxide (ZnO) nanoparticles has led to their wide distribution in consumer products, despite only a limited understanding of how this nanomaterial behaves within biological systems. From a nanotoxicological viewpoint the interaction(s) of ZnO nanoparticles with cells of the immune system is of specific interest, as these nanostructures are readily phagocytosed. In this study, rapid scanning X-ray fluorescence microscopy was used to assay the number ZnO nanoparticles associated with ∼1000 in idual THP-1 monocyte-derived human macrophages. These data showed that nanoparticle-treated cells endured a 400% elevation in total Zn levels, 13-fold greater than the increase observed when incubated in the presence of an equitoxic concentration of ZnCl2. Even after excluding the contribution of internalized nanoparticles, Zn levels in nanoparticle treated cells were raised ∼200% above basal levels. As dissolution of ZnO nanoparticles is critical to their cytotoxic response, we utilized a strategy combining ion beam milling, X-ray fluorescence and scanning electron microscopy to directly probe the distribution and composition of ZnO nanoparticles throughout the cellular interior. This study demonstrated that correlative photon and ion beam imaging techniques can provide both high-resolution and statistically powerful information on the biology of metal oxide nanoparticles at the single-cell level. Our approach promises ready application to broader studies of phenomena at the interface of nanotechnology and biology.
Publisher: MDPI AG
Date: 24-05-2012
DOI: 10.3390/MA5050937
Publisher: Informa UK Limited
Date: 18-04-2023
Publisher: Elsevier BV
Date: 09-2023
Location: United Kingdom of Great Britain and Northern Ireland
Location: Australia
Start Date: 2020
End Date: 12-2021
Amount: $1,486,000.00
Funder: Australian Research Council
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