5 results for Anderson, N.G.

  • Reducing beam hardening effects and metal artefacts using Medipix3RX: With applications from biomaterial science

    Rajendran, K.; Walsh, M.F.; de Ruiter, N.J.A.; Chernoglazov, A.I.; Panta, R.K.; Butler, A.P.H.; Butler, P.H.; Bell, S.T.; Anderson, N.G.; Woodfield, T.B.F.; Tredinnick, S.J.; Healy, J.L.; Bateman, C.J.; Aamir, R.; Doesburg, R.M.N.; Renaud, P.F.; Gieseg, S.P.; Smithies, D.J.; Mohr, J.L.; Mandalika, V.B.H.; Opie, A.M.T.; Cook, N.J.; Ronaldson, J.P.; Nik, S.J.; Atharifard, A.; Clyne, M.; Bones, P.J.; Bartneck, C.; Grasset, R.; Schleich, N.; Billinghurst, M. (2014)

    Journal Articles
    University of Canterbury Library

    This paper discusses methods for reducing beam hardening effects using spectral data for biomaterial applications. A small-animal spectral scanner operating in the diagnostic energy range was used. We investigate the use of photon-processing features of the Medipix3RX ASIC in reducing beam hardening and associated artefacts. A fully operational charge summing mode was used during the imaging routine. We present spectral data collected for metal alloy samples, its analysis using algebraic 3D reconstruction software and volume visualisation using a custom volume rendering software. Narrow high energy acquisition using the photon-processing detector revealed substantial reduction in beam hardening effects and metal artefacts.

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  • Contrast agent recognition in small animal CT using the Medipix2 detector

    Firsching, M.; Butler, A.P.H.; Scott, N.; Anderson, N.G.; Michel, T.; Anton, G.; MARS-CT Team (2009)

    Journal Articles
    University of Canterbury Library

    Energy resolving capabilities of X-ray detectors like the Medipix2 and the upcoming Medipix3 offer access to spectral information which is a new domain of information in medical imaging. In conventional CT of a composite object only the cumulative contribution of all involved materials to the attenuation is measurable, but not how much each material component contributes to this attenuation is measured. Therefore, contrast agent cannot be distinguished from bone or calcifications. The method of material reconstruction exploits the energy information to determine the partial densities of the involved materials using a maximum likelihood approach, i.e. it allows the separation of contrast agent from tissue, bones and calcifications. We have employed the Medipix All Resolution System (MARS) scanner equipped with a Medipix2 MXR and performed a CT scan of a mouse with iodine contrast agent in stomach and bowel. The method allows to separate the iodine contrast agent from all the other absorbing structures. In the iodine image, only the iodine concentration is visible, while the non-iodine (water) image shows all the other tissue structures and bones. The method of material reconstruction was applied to real CT data of a biological sample for the first time.

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  • Multiple contrast agent imaging using MARS-CT, a spectroscopic (multi-energy) photon counting microCT scanner

    Butler, A.P.H.; Anderson, N.G.; Hurrell, M.A.; Cook, N.J.; Scott, N.J.; Butler, P.H. (2009)

    Conference Contributions - Published
    University of Canterbury Library

    Purpose: To establish that a spectroscopic (multi-energy) CT scanner can differentiate multiple contrast agents and background tissues. This is clinically significant because it enables multi-phase contrast studies to be performed in a single scan. eg. A "triple phase liver" is possible in a one acquisition. This is a significant improvement from dual energy CT which is limited to non-contrast and post-contrast images from a single acquisition.

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  • Bio-medical X-ray imaging with spectroscopic pixel detectors

    Butler, A.P.H.; Anderson, N.G.; Tipples, R.; Cook, N.; Watts, R.; Meyer, J.; Bell, A.J.; Melzer, T.R.; Butler, P.H. (2008)

    Journal Articles
    University of Canterbury Library

    The aim of this study is to review the clinical potential of spectroscopic X-ray detectors and to undertake a feasibility study using a novel detector in a clinical hospital setting. Detectors currently in development, such as Medipix-3, will have multiple energy thresholds allowing for routine use of spectroscopic bio-medical imaging. We have coined the term MARS (Medipix All Resolution System) for bio-medical images that provide spatial, temporal, and energy information. The full clinical significance of spectroscopic X-ray imaging is difficult to predict but insights can be gained by examining both image reconstruction artifacts and the current uses of dual-energy techniques. This paper reviews the known uses of energy information in vascular imaging and mammography, clinically important fields. It then presents initial results from using Medipix-2, to image human tissues within a clinical radiology department. Detectors currently in development, such as Medipix-3, will have multiple energy thresholds allowing for routine use of spectroscopic bio-medical imaging in the future.

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  • Pilot Study to Confirm that Fat and Liver can be Distinguished by Spectroscopic Tissue Response on a Medipix-All-Resolution System-CT (MARS-CT)

    Berg, K.B.; Carr, J.M.; Clark, M.J.; Cook, N.J.; Anderson, N.G.; Scott, N.J.; Butler, A.P.M.; Butler, P.H.; Butler, A.P.H.; MARS-CT Team (2009)

    Conference Contributions - Published
    University of Canterbury Library

    NAFLD, liver component of the “metabolic” syndrome, has become the most common liver disease in western nations. Non-invasive imaging techniques exist, but have limitations, especially in detection and quantification of mild to moderate fatty liver. In this pilot study, we produced attenuation curves from biomedical-quality projection images of liver and fat using the MARS spectroscopic-CT scanner. Difficulties obtaining attenuation spectra after reconstruction demonstrated that standard reconstruction programs do not preserve spectral information.

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