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Browsing by Author "Cong, Wenxiang"

Now showing 1 - 9 of 9
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    Experimental Study on Bioluminescence Tomography with Multimodality Fusion
    Lv, Yujie; Tian, Jie; Cong, Wenxiang; Wang, Ge (Hindawi, 2007-09-10)
    To verify the influence of a priori information on the nonuniqueness problem of bioluminescence tomography (BLT), the multimodality imaging fusion based BLT experiment is performed by multiview noncontact detection mode, which incorporates the anatomical information obtained by the microCT scanner and the background optical properties based on diffuse reflectance measurements. In the reconstruction procedure, the utilization of adaptive finite element methods (FEMs) and a priori permissible source region refines the reconstructed results and improves numerical robustness and efficiency. The comparison between the absence and employment of a priori information shows that multimodality imaging fusion is essential to quantitative BLT reconstruction.
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    Extended interior methods and systems for spectral, optical, and photoacoustic imaging
    (United States Patent and Trademark Office, 2014-10-14)
    The present invention relates to the field of medical imaging. More particularly, embodiments of the invention relate to methods, systems, and devices for imaging, including for tomography-based applications. Embodiments of the invention include, for example, a computed tomography based imaging system comprising: (a) at least one wide-beam gray-scale imaging chain capable of performing a global scan of an object and acquiring projection data relating to the object; (b) at least one narrow-beam true-color imaging chain capable of performing a spectral interior scan of a region of interest (ROI) of and acquiring projection data relating to the object; (c) a processing module operably configured for: (1) receiving the projection data; (2) reconstructing the ROI into an image by analyzing the data with a color interior tomography algorithm, aided by an individualized gray-scale reconstruction of an entire field of view (FOV), including the ROI; and (d) a processor for executing the processing module. The extended interior methods and systems for spectral, optical, and photoacoustic imaging presented in this application can lead to better medical diagnoses by providing images with higher resolution or quality, and can lead to safer procedures by providing systems capable of reducing a patient's exposure time to, and thus quantity of, potentially harmful x-rays. Embodiments of the invention also provide tools for real-time tomography-based analyses.
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    Hybrid detector modules and dynamic thresholding for spectral CT
    (United States Patent and Trademark Office, 2018-01-09)
    A system and method that comprises an X-ray source configured to emit an X-ray beam; an object positioned to receive the X-ray beam; a detector configured to receive an attenuated beam of the X-rays through the object for measuring projection data from various orientations that can be used to generate spectral images in terms of energy-dependent linear attenuation coefficients, and a detector, as described above, comprising one or more energy-integrating detector elements and one or more photon counting detector elements in one or more detectors array or separate detector arrays. The photon counting detector elements may also use dynamic thresholds to define energy windows.
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    Image Reconstruction For Bioluminescence Tomography From Partial Measurement
    Jiang, Ming; Zhou, Tie; Cheng, Jiantao; Cong, Wenxiang; Wang, Ge (Optical Society of America, 2007-09-01)
    The bioluminescence tomography is a novel molecular imaging technology for small animal studies. Known reconstruction methods require the completely measured data on the external surface, although only partially measured data is available in practice. In this work, we formulate a mathematical model for BLT from partial data and generalize our previous results on the solution uniqueness to the partial data case. Then we extend two of our reconstruction methods for BLT to this case. The first method is a variant of the well-known EM algorithm. The second one is based on the Landweber scheme. Both methods allow the incorporation of knowledge-based constraints. Two practical constraints, the source non-negativity and support constraints, are introduced to regularize the BLT problem and produce stability. The initial choice of both methods and its influence on the regularization and stability are also discussed. The proposed algorithms are evaluated and validated with intensive numerical simulation and a physical phantom experiment. Quantitative results including the location and source power accuracy are reported. Various algorithmic issues are investigated, especially how to avoid the inverse crime in numerical simulations. (c) 2007 Optical Society of America.
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    Improving the Accuracy of the Diffusion Model in Highly Absorbing Media
    Cong, Alexander X.; Shen, Haiou; Cong, Wenxiang; Wang, Ge (Hindawi, 2007-08-29)
    The diffusion approximation of the Boltzmann transport equation is most commonly used for describing the photon propagation in turbid media. It produces satisfactory results in weakly absorbing and highly scattering media, but the accuracy lessens with the decreasing albedo. In this paper, we presented a method to improve the accuracy of the diffusion model in strongly absorbing media by adjusting the optical parameters. Genetic algorithm-based optimization tool is used to find the optimal optical parameters. The diffusion model behaves more closely to the physical model with the actual optical parameters substituted by the optimized optical parameters. The effectiveness of the proposed technique was demonstrated by the numerical experiments using the Monte Carlosimulation data as measurements.
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    Mathematical Study and Numerical Simulation of Multispectral Bioluminescence Tomography
    Han, Weimin; Cong, Wenxiang; Wang, Ge (Hindawi, 2006-12-12)
    Multispectral bioluminescence tomography (BLT) attracts increasinglymore attention in the area of optical molecular imaging. In this paper, we analyzethe properties of the solutions to the regularized and discretized multispectralBLT problems. First, we show the solution existence, uniqueness, and itscontinuous dependence on the data. Then, we introduce stable numerical schemes andderive error estimates for numerical solutions. We report some numerical resultsto illustrate the performance of the numerical methods on the quality of multispectralBLT reconstruction.
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    Multi-parameter X-ray computed tomography
    (United States Patent and Trademark Office, 2012-02-21)
    The present invention relates to the field of x-ray imaging. More particularly, embodiments of the invention relate to methods, systems, and apparatus for imaging, which can be used in a wide range of applications, including medical imaging, security screening, and industrial non-destructive testing to name a few. Specifically provided as embodiments of the invention are systems for x-ray imaging comprising: a) a first collimator-and-detector assembly having a first operable configuration to provide at least one first dataset comprising primary x-ray signals as a majority component of its data capable of being presented as a first image of an object subjected to x-ray imaging; b) a second collimator-and-detector assembly having a second operable configuration or wherein the first collimator-and-detector assembly is adjustable to a second configuration to provide at least one second dataset comprising primary and dark-field x-ray signals as a majority component of its data capable of being presented as a second image of the object; and c) a computer operably coupled with the collimator-and-detector assemblies comprising a computer readable medium embedded with processing means for combining the first dataset and the second dataset to extract the dark-field x-ray signals and produce a target image having higher contrast quality than the images based on the first or second dataset alone. Such systems can be configured to comprise at least two collimator-and-detector assemblies or configurations differing with respect to collimator height, collimator aperture, imaging geometry, or distance between an object subjected to the imaging and the collimator-and-detector assembly.
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    Towards Omni-Tomography-Grand Fusion of Multiple Modalities for Simultaneous Interior Tomography
    Wang, Ge; Zhang, Jie; Gao, Hao; Weir, Victor; Yu, Hengyong; Cong, Wenxiang; Xu, Xiaochen; Shen, Haiou; Bennett, James; Furth, Mark; Wang, Yue; Vannier, Michael W. (PLOS, 2012-06-29)
    We recently elevated interior tomography from its origin in computed tomography (CT) to a general tomographic principle, and proved its validity for other tomographic modalities including SPECT, MRI, and others. Here we propose “omni-tomography”, a novel concept for the grand fusion of multiple tomographic modalities for simultaneous data acquisition in a region of interest (ROI). Omni-tomography can be instrumental when physiological processes under investigation are multi-dimensional, multi-scale, multi-temporal and multi-parametric. Both preclinical and clinical studies now depend on in vivo tomography, often requiring separate evaluations by different imaging modalities. Over the past decade, two approaches have been used for multimodality fusion: Software based image registration and hybrid scanners such as PET-CT, PET-MRI, and SPECT-CT among others. While there are intrinsic limitations with both approaches, the main obstacle to the seamless fusion of multiple imaging modalities has been the bulkiness of each individual imager and the conflict of their physical (especially spatial) requirements. To address this challenge, omni-tomography is now unveiled as an emerging direction for biomedical imaging and systems biomedicine.
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    Varying Collimation for Dark-Field Extraction
    Wang, Ge; Cong, Wenxiang; Shen, Haiou; Zou, Yu (Hindawi, 2010-02-16)
    Although x-ray imaging is widely used in biomedical applications, biological soft tissues have small density changes, leading to low contrast resolution for attenuation-based x-ray imaging. Over the past years, x-ray small-angle scattering was studied as a new contrast mechanism to enhance subtle structural variation within the soft tissue. In this paper, we present a detection method to extract this type of x-ray scattering data, which are also referred to as dark-field signals. The key idea is to acquire an x-ray projection multiple times with varying collimation before an x-ray detector array. The projection data acquired with a collimator of a sufficiently high collimation aspect ratio contain mainly the primary beam with little scattering, while the data acquired with an appropriately reduced collimation aspect ratio include both the primary beam and small-angle scattering signals. Then, analysis of these corresponding datasets will produce desirable dark-field signals; for example, via digitally subtraction. In the numerical experiments, the feasibility of our dark-field detection technology is demonstrated in Monte Carlo simulation. The results show that the acquired dark field signals can clearly reveal the structural information of tissues in terms of Rayleigh scattering characteristics.