Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 20 of 28 for “"Image reconstruction algorithms"”.
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INVESTIGATION OF ADVANCED IMAGE RECONSTRUCTION ALGORITHMS FOR ELECTRON MICROSCOPY
… there is an increasing demand for advanced algorithms to work with new experimental data or improve existing techniques. In this dissertation, we investigate a variety of image reconstruction algorithms for tomography and ptychography - two fast growing areas in electron microscopy. Using …
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Development and Implementation of Fully 3D Statistical Image Reconstruction Algorithms for Helical CT and Half-Ring PET Insert System
… imaging modalities for screening, diagnosis, and image-guided treatment planning. Along with the increased clinical use are increased demands for high image quality with reduced ionizing radiation dose to the patient. Despite their significantly high computational cost, statistical iterative …
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Three-Dimensional Photoacoustic Computed Tomography: Imaging Models and Reconstruction Algorithms
… of experimental designs. Meanwhile, a variety of image reconstruction algorithms have been developed for the purpose of computed tomography. Most of these algorithms assume full knowledge of the acoustic pressure function on a measurement surface that either encloses the object or extends to …
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COMPARATIVE STUDIES OF DIFFERENT SYSTEM MODELS FOR ITERATIVE CT IMAGE RECONSTRUCTION
… are compared in the content of iterative CT image reconstruction algorithms. One of the key factors that limit the clinical application of an iterative reconstruction algorithm is the high computational cost which mainly depends on the system model. This thesis can serve as the basis for the …
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Image Reconstruction in Photoacoustic Computed Tomography with Acoustically Heterogeneous Media
… hybrid imaging modality that combines optical image contrast with ultrasound detection. The majority of currently available PACT image reconstruction algorithms are based on idealized imaging models that assume a lossless and acoustically homogeneous medium. However, in many applications of …
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Reconstruction algorithms for MRI
This dissertation presents image reconstruction algorithms for Magnetic Resonance Imaging (MRI) that aims to increase the imaging efficiency. Algorithms that reduce imaging time without sacrificing the image quality and mitigate image artifacts are proposed. The goal of increasing the MR efficiency …
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Image Reconstruction of the Speed of Sound and Initial Pressure Distributions in Ultrasound Computed Tomography and Photoacoustic Computed Tomography
… remains to realize this promise. First, USCT image reconstruction methods based on the acoustic wave equation, known as waveform inversion methods, are computationally burdensome, limiting their widespread use. Instead, image reconstruction methods based on geometric acoustics are often …
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A Geant4 Simulation Study Of A Xenon-Doped Liquid Argon, Full-Body, Time-of-Flight Positron Emission Tomography Scanner To Understand Its Performance And Noise Profile
… application of newer detection technologies and image reconstruction algorithms. However, current PET scanners possess a small field of view which limits the overall sensitivity. Increasing the sensitivity and using Time of Flight (TOF) information can help to improve the quality of PET scans. …
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Time domain synthetic aperture radar image processing using fast factorised backprojection
… Backprojection(FBP) to produce high quality images in the spatial domain at speeds which rival spectral domain SAR focusing methods. Synthetic Aperture Radar (SAR) focusing is fundamentally a matched filtering process which can be performed both in the spatial or spectral domain. Spatial …
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Tomographic processing of synthetic aperture radar signals for enhanced resolution
… over the ground patch. This allows high-quality image reconstruction in the face of arbitrary amounts of wavefront curvature such as would be present when the angle subtended by the ground patch, as seen by the radar, is not small. One such application is wide-area surveillance. A methodology is …
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Design and simulation of a rapid high percision profilometer
… hardware, (4) probe tip calibration and image processing, and (5) scanned image processing and convolution. The primary focus of this thesis is on the probe positioning hardware design and simulation of the customized profilometer. The design enables the system to simultaneously scan both …
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Modeling and characterization of a monoenergetic gamma-ray imaging system for active interrogation applications
… a container while increasing penetration and image contrast. In this work, imaging beams are tested for beam penetration, dose, and scatter within the container. It is found that higher energy beams scatter less widely, and can offer dose reductions to the cargo on the order of 40-60% while …
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Design and Optimization of Four-Dimensional Cone-Beam Computed to mography In Image-Guided Radiation Therapy
… computed tomography (4D-CBCT), which acquires an image set of the dynamic target throughout the respiratory cycle during the therapy session. 4D-CBCT is undersampled if the scan time is too short. However, short scan time is desirable in clinical practice to reduce patient setup time. This …
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Synthetic aperture radar-based techniques and reconfigurable antenna design for microwave imaging of layered structures
… require more advanced imaging systems and image reconstruction algorithms (post-processing) suitable for imaging inhomogeneous (i.e., layered) media. Currently-available imaging algorithms are not always robust, easy to implement, and fast. Synthetic aperture radar (SAR) techniques are some …
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Belęšė holografijos sistema žadinimo zondavimo eksperimentuose /
… has emerged, leveraging digital sensors and image reconstruction algorithms to overcome many of the traditional limitations [3]. This thesis focuses on the construction and application of a lensless digital holography system designed for pump-probe experiments. By removing the lens from the …
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MOBILE, HYBRID COMPTON/CODED APERTURE IMAGING FOR DETECTION, IDENTIFICATION AND LOCALIZATION OF GAMMA-RAY SOURCES AT STAND-OFF DISTANCES
… dynamic backgrounds. The Raytheon-Tri-Modal Imager (TMI) is a mobile truck-based, hybrid gamma-ray spectroscopic and imaging system able to quickly detect, identify and localize, radiation sources at standoff distances through improved sensitivity provided by multiple detection modes while …
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Optimizing Kilovoltage Cone-Beam Computed Tomography for Image-Guided Radiation Therapy
… (kV CBCT) has important applications in image guided radiation therapy (IGRT). In its current state, CBCT is suboptimal for these applications due to its considerable radiation dose, poor soft-tissue contrast and inaccurate Hounsfield Units as a result of in-patient scatter. The specific …
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Prior Information Guided Image Processing and Compressive Sensing
Signal/image processing and reconstruction based on mathematical modeling and computational techniques have been well developed and still attract much attention due to their broad applications. It becomes challenging to build mathematical models if the given data lacks some certainties. Prior …
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Optimization of Fast MR Imaging Technologies using the Case-PDM to Quantitatively Assess Image Quality
… an extraordinary number of ways to create an MR image, and the number seems to grow daily. In almost all cases, images will be viewed by radiologists to make a diagnosis, to stage a disease, to apply a treatment, and/or to assess a treatment. Since images are viewed, one needs to assess visual …
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Dual energy image reconstruction and systems for application in proton therapy treatment planning
… makes use of CT spectra to create two sets of CT images simultaneously. DECT relies on the energy independence of relative electron density, and the energy and atomic number dependence of X-ray interaction atomic cross-sections. Post processing of the two reconstructed CT images results in two …
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