Browsing by Author "Aminzadeh, A"

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    Imaging breast microcalcifications using dark-field signal in propagation-based phase-contrast tomography
    (IEEE, 2022-05-18) Aminzadeh, A; Arhatari, BD; Maksimenko, A; Hall, CJ; Häusermann, D; Peele, AG; Fox, J; Kumar, B; Prodanovic, Z; Dimmock, MR; Lockie, D; Pavlov, KM; Nesterets, YI; Thompson, D; Mayo, SC; Paganin, DM; Taba, ST; Lewis, SJ; Brennan, PC; Quiney, HM; Gureyev, TE
    Breast microcalcifications are an important primary radiological indicator of breast cancer. However, microcalcification classification and diagnosis may be still challenging for radiologists due to limitations of the standard 2D mammography technique, including spatial and contrast resolution. In this study, we propose an approach to improve the detection of microcalcifications in propagation-based phase-contrast X-ray computed tomography of breast tissues. Five fresh mastectomies containing microcalcifications were scanned at different X-ray energies and radiation doses using synchrotron radiation. Both bright-field (i.e. conventional phase-retrieved images) and dark-field images were extracted from the same data sets using different image processing methods. A quantitative analysis was performed in terms of visibility and contrast-to-noise ratio of microcalcifications. The results show that while the signal-to-noise and the contrast-to-noise ratios are lower, the visibility of the microcalcifications is more than two times higher in the dark-field images compared to the bright-field images. Dark-field images have also provided more accurate information about the size and shape of the microcalcifications. © 2023 IEEE
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    Imaging breast microcalcifications using dark-field signal in propagation-based phase-contrast tomography
    (Australian Nuclear Science and Technology Organisation, 2021-11-24) Aminzadeh, A; Arhatari, BD; Maksimenko, A; Hall, CJ; Häusermann, D; Peele, AG; Fox, J; Kumar, B; Prodanovic, Z; Dimmock, MR; Lockie, D; Pavlov, KM; Thompson, D; Mayo, SC; Paganin, DM; Tavakoli, A; Lewis, SJ; Brennan, PC; Quiney, HM; Gureyev, TE
    Breast microcalcifications are an important primary radiological indicator of breast cancer. However, microcalcification classification and diagnosis can be still challenging for radiologists due to limitations of the standard 2D mammography technique, including spatial and contrast resolution. In this study, we propose an approach to improve the detection of microcalcifications in propagation-based phase-contrast X-ray tomography (PB-CT) of breast tissues. Five fresh mastectomies containing microcalcifications were scanned at the Imaging and Medical beamline of the Australian Synchrotron at different X-ray energies and radiation doses. Both bright-field and dark-field images were extracted from the same data sets using different image processing methods [1]. A quantitative analysis was performed in terms of visibility and contrast-to-noise ratio of microcalcifications. The results show that the visibility of the microcalcifications in the dark-field images is more than two times higher compared to the bright-field images. Dark-field images have also provided more accurate information about the size and shape of the microcalcifications [2]. Therefore, dark-field PB-CT images are likely to help radiologists evaluate the probability of breast cancer more effectively. This work has been conducted in the course of developing a medical imaging facility at the Australian Synchrotron for advanced breast cancer imaging. © The Authors
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    Investigation and optimization of reactive ion etching of Si3N4 and polyphthalaldehyde for two-step gray scale fabrication of diffractive optics
    (AIP, 2019-11-18) Aminzadeh, A; Bose, M; Smith, D; Uddin, MH; Peele, AG; van Riessen, GA
    Nanofabrication of x-ray diffractive optics using electron beam lithography requires a complex process of electron exposure optimization and resist development. Thermal scanning probe lithography (TSPL) offers a high resolution, maskless, gray scale patterning method with reduced complexity. Thin diffractive optics with high efficiency for the extreme ultraviolet (EUV) and soft x-ray (SXR) photon range could be fabricated by combining TSPL with a single etching step if the TSPL resist, polyphthalaldehyde (PPA), can be used as an etch mask to direct-etch the pattern into a substrate using reactive ion etching. This condition critically depends on high etch selectivity between the substrate and the PPA, because TSPL resolution deteriorates as the PPA patterning depth increases beyond tens of nanometers. In this work, the authors have evaluated the etch selectivity for PPA and Si3N4 using SF6/C4F8 gases and the influence of process parameters, including gas flow rate, vacuum pressure, radio frequency bias power, and inductively coupled plasma power. The experimental results indicate that an etch selectivity of 7 (Si3N4:PPA) is achievable, and the authors demonstrate that diffractive optics for EUV/SXR can be fabricated in only two steps. © 2023 AIP