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    A miniaturized optical tomography platform for volumetric imaging of engineered living systems
    (Royal Soc Chemistry, 2019) Polat, Adem; Hassan, Shabir; Yildirim, Isa; Oliver, Luis Eduardo; Mostafaei, Maryam; Kumar, Siddharth; Maharjan, Sushila
    Volumetric optical microscopy approaches that enable acquisition of three-dimensional (3D) information from a biological sample are attractive for numerous non-invasive imaging applications. The unprecedented structural details that these techniques provide have helped in our understanding of different aspects of architecture of cells, tissues, and organ systems as they occur in their natural states. Nonetheless, the instrumentation for most of these techniques is sophisticated, bulky, and costly, and is less affordable to most laboratory settings. Several miniature imagers based on webcams or low-cost sensors featuring easy assembly have been reported, for in situ imaging of biological structures at low costs. However, they have not been able to achieve the ability of 3D imaging throughout the entire volumes for spatiotemporal analyses of the structural changes in these specimens. Here we present a miniaturized optical tomography (mini-Opto) platform for lowcost, volumetric characterization of engineered living systems through hardware optimizations as well as applications of an optimized algebraic algorithm for image reconstruction.
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    Digital Breast Tomosynthesis imaging using compressed sensing based reconstruction for 10 radiation doses real data
    (Elsevier Sci Ltd, 2019) Polat, Adem; Matela, Nuno; Dinler, Ali; Zhang, Yu Shrike; Yildirim, Isa
    Purpose: Digital Breast Tomosynthesis (DBT) has recently proved promising in producing three-dimensional (3D) images of a breast. Algebraic reconstruction technique (ART), which is one of the most frequently used iterative image reconstruction techniques, has been proposed to provide satisfactory images of the breast in detecting masses and micro-calcifications. However, the greatest limitation of DBT imaging is the level of radiation dose due to the very sensitive nature of the breast. Recently, the effect of total variation (TV) minimization to enhance the image quality and to reduce the noise has been investigated in DBT imaging. Studies dealing with 3D TV minimization with ART have attracted increasing attention in the field of image reconstruction. This work investigates if iterative reconstruction techniques applied without and with TV (ART and ART + TV3D) can help reduce the level of dose in DBT imaging. Methods: Projections of a realistic breast phantom (CD Pasmam 1054) were acquired with a Siemens MAMMOMAT DBT scanner at 10 different doses. The effect of dose and the methods in the reconstruction quality was assessed both quantitatively and qualitatively. Results: ART+ TV3D showed superior results in terms of visual assessment, contrast-to-noise ratio (CNR) and full width at half maximum (FWHM) values, and one-dimensional (1D) profiles compared with ART. CNR values were evaluated for two different regions of interest (ROls). For instance, CNR values of ROI-1 of ART and of ART + TV3D were 46.380 and 47.675 at 63 mAs, 48.945 and 50.632 at 90 mAs, and 51.248 and 52.867 at 199 mAs, respectively. Additionally, FWHM values for ART and ART + TV3D were 2.373 and 1.758 at 63 mAs, 1.930 and 1.467 at 90 mAs, and 1.591 and 1.223 at 199 mAs, respectively. Conclusions: The results suggested that a compressed sensing based iterative reconstruction method (ART +TV3D) could help decrease the radiation dose level that is one of the most critical limitations of DBT imaging. (C) 2018 Published by Elsevier Ltd.