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 50 for “"X-ray CT"”.
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Automated defect detection and evaluation in X-ray CT images
X-ray computed tomography gains increasing popularity for industrial quality inspection tasks. It is a challenge however to use it in a fully automated assembly line, which requires robust algorithms for volumetric image analysis on noisy data. This work provides methods for the automatic detection …
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List Mode Reconstruction in X-Ray CT and SPECT Imaging
Since the introduction of tomography imaging in the 1970s, it has become an indispensable tool in medical imaging, driving continuous advancements in pursuit of higher image quality, reduced scan time, lower radiation doses, and more recorded attributes. List mode data, which records all attributes …
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Segmentation of brain x-ray CT images using seeded region growing
… dissertation. They are intracranial volume extraction, noise suppression and automated segmentation of X-Ray Computerized Tomography (CT) images. The segmentation scheme is based on a Seeded Region Growing algorithm. The intracranial volume extraction is based on image symmetry and the noise …
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X-ray CT scatter correction by a physics-motivated deep neural network
A fundamental problem in X-ray Computed Tomography (CT) is the scatter occurring due to the interaction of photons with the imaged object. Unless it is corrected, this phenomenon manifests itself as degradations in the reconstructions in the form of various artifacts. This makes scatter correction …
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Alternating Minimization Algorithms for Dual-Energy X-Ray CT Imaging and Information Optimization
… contributes toward solutions to two distinct problems linked through the use of common information optimization methods. The first problem is the X-ray computed tomography (CT) imaging problem and the second is the computation of Berger-Tung bounds</p><p>for the lossy distributed source …
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Synthesis and Characterization of New Probes for use in Fluorescence and X-ray CT Bioimaging
… would then, however, be necessary to conduct any kind of mechanistic or interaction studies for he said drug within the biological system. Just to name a few, fluorescence and X-ray computed tomography (CT) methods allow for imaging of biological systems but require the need of compounds …
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Advanced Statistical Modeling for Model-Based Iterative Reconstruction for Single-Energy and Dual-Energy X-Ray CT
Model-based iterative reconstruction (MBIR) has been increasingly broadly applied as an improvement over traditional, analytical image reconstruction methods in X-ray CT, primarily due to its significant advantage in drastic dose reduction without diagnostic loss. Early success of the method in …
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Application of HPGR and X-Ray CT to investigate the potential of Witwatersrand gold ore for heap leaching : a process mineralogy approach
… For the past 40 years, Witwatersrand gold production in South Africa has been progressively declining due to problems related to high energy costs, decreasing grade, accessibility to greater depths, health and safety issues, labour union unrest and economic uncertainties: thus the overall …
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Characterization of the cellular structure of foamed cement using x-ray computed tomography
The primary objectives of this thesis were to investigate and quantify the cellular structure of foamed cement samples at varying densities as well as to demonstrate X-ray computed tomography (CT) as a valuable three dimensional (3D) characterization technique for the investigation of cementitious …
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Applications of Statistical Modeling in Iterative CT Image Reconstruction
Traditionally, x-ray CT images are produced by an algorithm called filtered back projection, or FBP. FBP is an analytical solution to the idealized CT image reconstruction problem, the inverse problem of turning raw x-ray measurements into a full 3-dimensional (3D) image, and is derived assuming a …
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Image Reconstruction for X-ray Computed Tomography in Security Screening Applications
<p>X-ray tomographic systems have increasingly widespread use in security screening applications. For example, most major airports now utilize X-ray CT</p> <p>systems for efficient screening of baggage and cargo. While decades of research has benefited CT for medical diagnostics, a number of …
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Robust and efficient methods for proton computed tomography.
Proton computed tomography (pCT) is a recent promising imaging modality with the goal of generating accurate 3D maps of relative stopping power (RSP) with respect to water. Since the early developments of this imaging technique in 1970's, there have been significant improvements regarding the …
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The Software and Hardware Acceleration for Interior Tomography
The x-ray CT is with high spatial resolution, temporal resolutions, and high-speed imaging characteristic. The iterative reconstruction algorithms are becoming more important since they can reconstruct better image qualities from incomplete projection data compared to analytical reconstruction …
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Design and performance of a compact high-energy computed tomography system for the study of metal solidification
… study the feasibility of a computed tomography (CT) sensor useful to the metal casting industry to improve product quality and productivity. X-ray CT allows the non-destructive measurement of the two-dimensional density distribution in a given plane through an object. The solid and liquid phases …
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On the progression of leaching from large particles in heaps
… remains limited by low recoveries and long extraction times. It is becoming increasingly clear that the successful application of heap leaching technology will ultimately depend on having a comprehensive understanding of the underlying fundamental processes for optimisation to take place...The …
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Effect of soil structure on temporal and spatial dynamics of bacteria
… dynamic micro-habitats that have significant impacts on the growth and activity of resident microbiota. A question addressed in this research is how soil structure affects the temporal dynamics and spatial distribution of bacteria. Using repacked microcosms, the effect of bulk-density, aggregate …
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Fundamental studies of heap leaching hydrology using magnetic resonance imaging
… process requires the mineral to come into contact with the leaching solution. However, heap hydrology is prone to non-uniform behaviour due to the inhomogeneity of the ore particles and the heap structure. The primary aim of this thesis was therefore to develop a magnetic resonance imaging (MRI) …
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A survey of algebraic algorithms in computerized tomography
X-ray computed tomography (CT) is a medical imaging framework. It takes measured projections of X-rays through two-dimensional cross-sections of an object from multiple angles and incorporates algorithms in building a sequence of two-dimensional reconstructions of the interior structure. This …
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Characterization of lubricant-derived ash deposition within pores of Diesel Particulate Filters through non-destructive advanced imaging techniques
… decreasing overall engine efficiency. The objective of this work is to understand specifically how ash accumulates within the filter pores during early filter life, calling attention to the effect that the physical and geometric properties of the porous medium has on particulate deposition. …
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Iterative Reconstruction Algorithms for Polyenergetic X-ray Computerized Tomography
A reconstruction algorithm in computerized tomography is a procedure for reconstructing the attenuation coefficientscient, a real-valued function associated with the object of interest, from the measured projection data. Generally speaking, reconstruction algorithms in CT fall into two categories: …
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