Browsing by Author "Hall, C"

Now showing 1 - 4 of 4
  • No Thumbnail Available
    Item
    Energy optimisation of propagation-based phase-contrast computed tomography: a quantitative image quality assessment
    (SPIE, 2022-04-04) Lim, B; Lewis, S; Arhatari, BD; Nesterets, YI; Mayo, SC; Fox, J; Thomposon, D; Kumar, B; Häusermann, D; Maksimenko, A; Hall, C; Dimmock, M; Lockie, D; Rickard, M; Giannoitti, N; Peele, AG; Quiney, HM; Gureyev, TE; Brennan, PC; Taba, ST
    Purpose: This study aims at establishing the optimum x-ray energy for synchrotron acquired propagation-based computed tomography (PB-CT) images to obtain highest radiological image quality of breast mastectomy samples. It also examines the correlation between objective physical measures of image quality with subjective human observer scores to model factors impacting visual determinants of image quality. Approach: Thirty mastectomy samples were scanned at Australian Synchrotron’s Imaging and Medical Beamline. Samples were scanned at energies of 26, 28, 30, 32, 34, and 60 keV at a standard dose of 4mGy. Objective physical measures of image quality were assessed using signal-to-noise ratio (SNR), contrast-to-noise ratio (CNR), SNR/resolution (SNR/res), CNR/resolution (CNR/res) and visibility. Additional calculations for each measure were performed against reference absorption-based computer tomography (AB-CT) images scanned at 32 keV and 4mGy. This included differences in SNR (dSNR), CNR (dCNR), SNR/res (dSNR/res), CNR/res (dCNR/res), and visibility (dVis). Physical measures of image quality were also compared with visual grading analysis data to determine a correlation between observer scores and objective metrics. Results: For dSNR, dCNR, dSNR/res, dCNR/res, and dVis, a statistically significant difference was found between the energy levels. The peak x-ray energy for dSNR and dSNR/res was 60 keV. For dCNR and dCNR/res 34 keV produced the highest measure compared to 28 keV for dVis. Visibility and CNR correlate to 56.8% of observer scores. Conclusion: The optimal x-ray energy differs for different objective measures of image quality with 30-34 keV providing optimum image quality for breast PB-CT. Visibility and CNR correlate highest to medical imaging expert scores. © (2022) Society of Photo-Optical Instrumentation Engineers (SPIE).
  • Thumbnail Image
    Item
    Improved micro-CT of SiC/SiC ceramic matrix composite
    (Australian Institute of Physics, 2016-02-02) Thornton, J; Zonneveldt, M; Arhatari, BD; Kimpton, JA; Sesso, M; Kim, SY; Hall, C
    Ceramic matrix composites composed of silicon carbide fibres in a silicon carbide matrix (SiC/SiC) are being introduced into gas turbine engines. Their introduction will increase engine thrust by allowing high operating temperatures and also reduce weight. Unlike monolithic ceramics they are effectively tough with elastic energy being consumed in fibre pull-out during crack propagation. However, much work still needs to be done before these materials are fully understood. The authors have been mapping the crack propagation in SiC/SiC using micro-CT and in-situ mechanical loading. Bright synchrotron X-ray sources were used to provide the intensity to map the crack propagation in practical times. One run was performed using the IMBL using 25 keV X-rays, and a second using the powder diffraction beam line at 15 keV. The first run showed fibre pull-out but failed to resolve the effects of the fibre coatings. The use of 15 keV improved the image quality and enabled fibre coatings to be resolved. The poster will compare the two experimental set-ups and the two sets of images and discuss what factors contributed to the improvement in image quality. Ideas for further improvements will also be presented.
  • No Thumbnail Available
    Item
    Jaws caught on the IMBL
    (Australian Nuclear Science and Technology Organisation, 2021-11-25) Maksimenko, A; Reser, D; Häusermann, D; De Veer, M; Panagiotopoulou, O; Huveneers, C; Wright, D; Hall, C
    Maturational changes in feeding behaviour among sharks are associated with increased mineralisation of the teeth and jaws, but this relationship has only been demonstrated in a few species. Large, highly mobile shark species are rarely available for detailed anatomical study, despite their importance for ecological health and widespread interest among the general population. We examined the crania, jaws, and teeth of two great white sharks (Carcharodon carcharias), a 2.3 m juvenile and a 3.2 m young adult. The CT scans used a 230 keV (mean energy) polychromatic beam from the 4 Tesla wiggler, with a filtration of 6mmAl, 6mmCu, 3mmMo and 3mmPb. The detector was a Teledyne-Dalsa Xineos 3030HR with 100µm pixels, a width of 300mm, and a 1mm CsI converter for high efficiency at high energy. Image noise was reduced by collecting 18,000 projections per rotation to deliver an image quality good enough to segment out different tissue types. With a beam size of 300mm x 35mm, the shark head was covered by ‘tiling’, and stitching the tiles, with the full-head image made up of two columns and 21 tiles, to image a 600mm x 520mm area. Total scan time was 9 hours. The heads were also imaged using conventional CT and 7 Tesla MRI for finite element modelling of bite forces produced by the jaw musculature. These results will be compared with measurements of the difference in mineralisation of tooth and jaw cartilage between the two specimens to assess developmental changes in tooth and jaw hardness as the animals shift their diets from largely fish-based (juvenile) to larger prey, such as seals, scavenged whales and surfers (adults). © The Authors
  • Thumbnail Image
    Item
    Microtomography applications at the Imaging and Medical Beamline of the Australioan Synchrotron (sic)
    (Australian Microscopy and Microanalysis Society, 2016-02-04) Maksimenko, A; Acres, RG; Hall, C; Häusermann, D; Stevenson, AW; Livingston, J; Pearson, J
    The Imaging and Medical Beamline (IMBL) of the Australian Synchrotron (AS) is now becoming one of the most advanced instruments of this type in the world. It is designed to provide a wide variety of imaging techniques including but not limited to the in-line and analyzed phase contrasts, monochromatic and pink beam imaging. Three beamline’s enclosures at various distances, when combined with the 25kW superconducting multipole wiggler and double Laue bent monochromator provide the end user a good choice of beam characteristics ranging from the hi-flux for high resolution and size up to huge 48x5cm beam at 134m from the source with the allowed energy range 17-120kEv. The wide range of the area detectors allows the computed tomography (CT) and tomosynthesis methods to be applied to almost any known X-ray imaging modality. The beamline’s data acquisition system is directly linked to the high performance computing facilities tuned for the on-the-fly real-time reconstruction and 3D rendering. Deep integration of the acquisition, reconstruction and rendering facilities allows one to think of the their combination as of a single system with modular architecture. The system is designed for the fully automated experiments with minimal user interaction. This report summarizes implemented, designed and planned features of the beamline as applied to the microtomography experiments. Some latest outcomes of the CT system are presented with the samples coming of different fields of science: Biology, Geology, Paleontology, Medicine and others.