1. Articles in category: Student Theses

    1-24 of 276 1 2 3 4 ... 10 11 12 »
    1. Measuring 3D Optic Nerve Head Deformations using Digital Volume Correlation of in vivo Optical Coherence Tomography Data (Thesis)

      Measuring 3D Optic Nerve Head Deformations using Digital Volume Correlation of in vivo Optical Coherence Tomography Data (Thesis)

      The optic nerve head (ONH), located in the back of the eye, is a critical site in understanding the pathophysiology of glaucoma. However, longitudinal changes of the ONH as disease develops have not been well characterized. Our goal was to develop an improved tool to quantify these changes in an in vivo monkey model of glaucoma. Longitudinal spectral-domain optical coherence tomography (OCT) imaging of the ONH was performed every other week under manometric intraocular pressure (IOP) control (10 mmHg) in a monkey during baseline and after induction of unilateral experimental glaucoma. We developed a computational pipeline that applied digital volume ...

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    2. Optical coherence tomography for characterization of nanocomposite materials (Thesis)

      Optical coherence tomography for characterization of nanocomposite materials (Thesis)

      Nanocomposite materials play an increasingly important role in various application areas, be it in an industrial, medical or everyday environment. The unique properties of nanocomposites go beyond those of conventional composite materials. Because nanoparticles have a high surface-to-volume ratio such as carbon nanotubes, they can reinforce an embedding polymer host matrix mechanically, or they enhance the electrical material conductivity. A major challenge in the development of nanoparticles and nanocomposites is the control of particle size and shape, and of the uniform dispersion of nanoparticles in the host material. Conventional characterization techniques lack either resolution, or can only inspect details of ...

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    3. Red-light Heartbeat Control and Optical Coherence Microscopy (OCM) Imaging in Drosophila (Thesis)

      Red-light Heartbeat Control and Optical Coherence Microscopy (OCM) Imaging in Drosophila (Thesis)

      would like to thank my advisor Prof. Chao Zhou, who gave me the opportunity to pursue a higher-level education in the United States, and led me to the field of biomedical engineering. I still have the impression that I was attracted by the fast heartbeat of a Drosophila Prof. Zhou showed with a video in his presentation in Peking University in 2014. I was curious that how the fast heartbeat could be tracked using OCT. Fortunately, I got the opportunity to join the group during that summer. In the next several years during my PhD period, Prof. Zhou guided me ...

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    4. Functional High-Speed Optical Coherence Tomography (Thesis)

      Functional High-Speed Optical Coherence Tomography (Thesis)

      Optical coherence tomography (OCT) is a high speed, high resolution, noninvasive imaging technique that has seen applications across many clinical and biological research fields, with a particular focus in ophthalmic, cardiologic and dermatologic imaging. Ultrahigh speed OCT imaging has become of interest for high resolution, widefield in vivo imaging. Space division multiplexing optical coherence tomography (SDM-OCT) is a novel optical coherence tomography system which utilizes a parallel imaging approach to achieve ultrahigh imaging speeds. In this dissertation we develop an ophthalmic SDM-OCT system to obtain widefield structural and angiographic images of the human retina in vivo. With an 800 kHz ...

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    5. Robotics and Virtual Reality for Optical Coherence Tomography-Guided Ophthalmic Surgery and Diagnostics (Thesis)

      Robotics and Virtual Reality for Optical Coherence Tomography-Guided Ophthalmic Surgery and Diagnostics (Thesis)

      Ophthalmology is the only surgical specialty that routinely employs both microsurgical techniques and live intraoperative imaging, especially optical coherence tomography (OCT). Consequently, ophthalmic surgeons routinely face challenges in visualization and manipulation of small ocular tissues or in interpreting intraoperative imaging to guide their actions. This dissertation therefore seeks to advance the state-of-the-art in ophthalmic surgery with regards to manipulation, visualization, and interpretation. First, we address the interpretation challenge in ophthalmic surgery where live volumetric imaging from OCT systems recently incorporated into surgical microscopes has freed surgeons from the otherwise universal top-down viewpoint. These new viewpoints, however, disorient surgeons when directions ...

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    6. Advances in Optical Coherence Tomography for Retinal Oximetry and Angiography (Thesis)

      Advances in Optical Coherence Tomography for Retinal Oximetry and Angiography (Thesis)

      Optical coherence tomography (OCT) is a high-resolution, non-contact, three-dimensional imaging technique, which has revolutionized the diagnosis and treatment of retinal diseases. Visible-light OCT (vis-OCT) extends OCT by enabling retinal oximetry – the measurement of oxygen saturation of hemoglobin from within individual retinal blood vessels. Three advances in the vis-OCT technique are presented: an improved vis-OCT oximetry method based on circumpapillary scan and graph-search segmentation; the calibration, simulation, and correction of spectroscopic sensitivity rolloff for vis-OCT oximetry; and the measurement of the inner retinal oxygen metabolism in the 50/10 oxygen-induced retinopathy model, an animal model for human retinopathy of prematurity. Optical ...

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    7. The analysis of prostate tissue by optical coherence tomography (Thesis)

      The analysis of prostate tissue by optical coherence tomography (Thesis)

      The prostate is the gland located around the urethra beneath the bladder that produces most of the sperm fluid (figure 1). Prostate cancer (PCa) accounted for almost 1 in 5 new cancer diagnoses in males in the USA in 2017, and 1 in 8 men will develop invasive cancer in the prostate in their lifetime [1]. Prostate cancer is the second most common cancer in men (after skin cancer) and the second most common cause of cancer-related death (after lung cancer). Advances in screening, diagnosis, and treatment have led to an overall survival increase from 69% in 1991-1995 to 89 ...

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    8. Invasive Coronary Artery Imaging Using Optical Coherence Tomography: A Cost-effectiveness and Implementation Process Analysis (Thesis)

      Invasive Coronary Artery Imaging Using Optical Coherence Tomography: A Cost-effectiveness and Implementation Process Analysis (Thesis)

      The aim of this project was the implementation of optical coherence tomography (OCT), an invasive intracoronary imaging (ICI) tool used for the visualization of coronary arteries. The implementation was performed in a structured manner by: (1) A literature review into the current applications of OCT in relation to current standards; (2) A thesis feasibility study into clinical practices, professional views and other processes regarding ICI; (3) A Master’s thesis including a cost-effectiveness analysis (CEA) and the actual implementation of OCT at the department. The project started with a literature review about the current applications of OCT in relation to ...

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    9. DEVELOPMENT OF A LINE-FIELD MAGNETO-MOTIVE OPTICAL COHERENCE TOMOGRAPHY SYSTEM (Thesis)

      DEVELOPMENT OF A LINE-FIELD MAGNETO-MOTIVE OPTICAL COHERENCE TOMOGRAPHY SYSTEM (Thesis)

      The mechanism by which certain species of animals are able to detect the Earth’s magnetic field has remained a mystery for as long as we have known that they exhibit geomagnetic navigation. Certain species of bacteria are known to contain single chains of magnetite crystals, each with a diameter of ~50 nm, that are used to orient the bacteria. Searching for similar magnetoreceptors in larger animals requires a high-speed, high-resolution imaging system with the ability to detect single magnetic nanoparticles. Optical coherence tomography (OCT) is a biomedical imaging modality that produces 2D, cross-sectional images of optically turbid media with ...

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    10. Classification of Neural Tissue Types for an Endoscopic Full-field Optical Coherence Tomography Imaging System (Thesis)

      Classification of Neural Tissue Types for an Endoscopic Full-field Optical Coherence Tomography Imaging System (Thesis)

      Optical coherence tomography is a volumetric imaging technique that can differentiate brain regions with micron-scale resolution. Our group has previously developed an endoscopic full-field swept-source OCT system with the aim to provide real-time surgical guidance for the implantation of electrodes for deep brain stimulation. This thesis builds on our prior work. Due to the limitations in the resolution and contrast due to scattering from the tissue, to identify different types of neural tissues, we developed an image classification algorithm that use texture features and optical attenuation. The algorithm could classify three different brain regions in the ex vivo data set ...

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    11. Visible light spectroscopic optical coherence tomography for applications in neonatal healthcare (Thesis)

      Visible light spectroscopic optical coherence tomography for applications in neonatal healthcare (Thesis)

      In this thesis, we explored the opportunities of spatially resolved optical spectroscopy for neonatal healthcare. Hereto, we developed a setup that makes use of spectroscopic optical coherence tomography (sOCT). This technique allows for spectroscopic measurement of the attenuation of light within a confined measurement volume, without being influenced by surrounding tissues. Throughout this thesis, we explored the possibilities of sOCT for estimating tissue properties which are relevant to newborns. In this way, we hope to contribute to neonatal healthcare by enabling a non-invasive alternative for invasive blood sampling and by enabling more scientific research into human milk and lactation. The ...

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    12. Illuminating the trapeziometacarpal joint: Dawn for optical coherence tomography in osteoarthritis (Thesis)

      Illuminating the trapeziometacarpal joint: Dawn for optical coherence tomography in osteoarthritis (Thesis)

      Osteoarthritis (OA) is a debilitating degenerative joint disease affecting millions of patients worldwide and is characterized by loss of cartilage thickness and quality in affected joints. OA of the trapeziometacarpal (TMC) joint or thumb base joint especially gives rise to loss of hand function and disability. However, clinical imaging strategies have thus far been unable to accurately assess the thin cartilage layers lining small joints like the TMC joint. Moreover, a degree of discrepancy exists between clinical symptoms and OA features as seen on clinical imaging studies, hampering treatment choice. In an effort to eventually provide the clinician with additional ...

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    13. ASSESSING TERATOGEN-INDUCED CHANGES IN MURINE FETAL BRAIN VASCULATURE USING IN UTERO OPTICAL COHERENCE TOMOGRAPHY (Thesis)

      ASSESSING TERATOGEN-INDUCED CHANGES IN MURINE FETAL BRAIN VASCULATURE USING IN UTERO OPTICAL COHERENCE TOMOGRAPHY (Thesis)

      This dissertation reports the use of in utero optical coherence tomography to evaluate changes in vasculature in a developing murine fetal brain caused due to prenatal exposure to teratogens. Embryogenesis is a highly complex process that is extremely vulnerable to external factors. Proper visualization of embryonic development is crucial to understand the basic physiological processes and identify defects if any. This dissertation is divided into two major sections: 1) assessing teratogen induced changes in the murine fetal brain vasculature during the second trimester equivalent period (chapters 2-4) and 2) combining optical coherence tomography with Brillouin microscopy to image and evaluate ...

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    14. Optical reflectance contrast of micro- and nano-structures revealed with intravital micro-OCT (Thesis)

      Optical reflectance contrast of micro- and nano-structures revealed with intravital micro-OCT (Thesis)

      Optical coherence tomography (OCT) provides depth-resolved three-dimensional images allowing the visualization of subsurface microstructures over large areas in situ and thus is a promising tool for epithelial disease screening. However, it has generally been relegated to a nonspecific diagnostic tool because the optical reflectance (back-scattering) contrast in OCT images is poorly understood although some contrast agents are available for OCT. This thesis focuses on elucidating the microstructural and ultrastructural bases underlying optical contrast to explore if OCT could provide diagnostic information in epithelial tissues with specificity. We investigate the back-scattered intensity of different intracellular scatterers at the micrometer and nanometer ...

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    15. Investigating Local Polarisation Contrast With Fibre-Based Polarisation-Sensitive Optical Coherence Tomography and Microscopy (Thesis)

      Investigating Local Polarisation Contrast With Fibre-Based Polarisation-Sensitive Optical Coherence Tomography and Microscopy (Thesis)

      This thesis makes several important contributions to polarisation-sensitive optical coherence tomography (PS-OCT) through developing no el methods to effectively extract local contrast from birefringence and the orientation of the associated optic axis, at conventional and ultra-high resolution.

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    16. Design and Characterization of Tunable LC-VCSELs for Optical Coherence Tomography (Thesis)

      Design and Characterization of Tunable LC-VCSELs for Optical Coherence Tomography (Thesis)

      Optical Coherence Tomography (OCT) systems are making rapid progress into various areas ranging from medicine and health science up to non-medical areas such as quality control or biometrics. Various possible configurations are present in literature, but only a few exploit liquid crystals (LCs)-based device as a light source. The strength of OCT systems, compared with other three-dimensional imaging technologies, comes from a higher spatial resolution and a fast scanning rate that allows getting high-quality images of in vivo tissue samples. These qualities make OCT the perfect candidate for ophthalmology purpose, where the human eye moves quickly and randomly. The ...

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    17. Extending depth range of optical coherence tomography (Thesis)

      Extending depth range of optical coherence tomography (Thesis)

      Optical coherence tomography (OCT) is a noninvasive diagnostic imaging tool that has been established in various clinical fields. One of the most cited issue of OCT in clinical practices is the shortage of image depth range. This thesis proposes four novel techniques to significantly extend the depth range without compromising other imaging performances. The OCT depth range is fundamentally limited by two main factors, which are the axial field of view (FOV) and the system sensitivity. For standard OCT systems, the axial FOV can only be improved by decreasing the numerical aperture (NA) of the focusing optics, which unfortunately sacrifices ...

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    18. Exploring in vivo Optical Imaging Oximetry by Visible Light Optical Coherence Tomography (Thesis)

      Exploring in vivo Optical Imaging Oximetry by Visible Light Optical Coherence Tomography (Thesis)

      Biological functions rely on microvasculature to deliver oxygen and nutrients and carry away metabolic waste. Measuring microvascular oxygen saturation (sO2), the fraction of oxygensaturated hemoglobin relative to total hemoglobin (unsaturated + saturated) in the blood, can assess tissue oxygenation and provide insights into tissue metabolism, inflammation, and oxygen-related pathologies. Several major diseases, such as cancer, diabetes mellitus, cardiovascular diseases, hypertension, chronic kidney disease, and neurodegenerative diseases, are related to local microvascular sO2. Therefore, it is of crucial importance to demonstrate an accurate and reliable method to measure microvascular sO2 for early diagnosis, monitoring disease progression, and evaluating treatments of oxygen metabolism ...

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    19. Development of the human fovea after preterm birth measured using hand held spectral domain optical coherence tomography (HH SD-OCT) (Thesis)

      Development of the human fovea after preterm birth measured using hand held spectral domain optical coherence tomography (HH SD-OCT) (Thesis)

      Background: Much remains unknown about the influence of severity of prematurity and presence of retinopathy of prematurity (ROP) on the development of the fovea after preterm birth during the perinatal period from postmenstrual age (PMA) 30 to 44 weeks. Aims: Measures of foveal morphology, individual retinal layers and foveal oedema (CME), with and without ROP using HH-OCT, adjusting for gestational age (GA) and birthweight (BW). Methods: Prospective mixed cross-sectional and longitudinal study of infants (23 to 36 weeks GA). Foveal width, area, depth, central foveal thickness (CFT), individual retinal layers and CME severity were analysed. Infants with ROP were included ...

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    20. Optical Coherence Tomography for everyone (Thesis)

      Optical Coherence Tomography for everyone (Thesis)

      Optical Coherence Tomography (OCT) is a valuable tool which can non-invasively help not only clinicians, but also materials scientists and practitioners of various other fields. The relatively high costs of OCT instruments can be a deterrent to the application of OCT in academic settings. In work done at the Department of Physics, Sri Sathya Sai Institute of Higher Learning, Deemed to be University, located in a rural area of Anantapur district, Andhra Pradesh, India, we have attempted to make OCT more accessible by exploring options to lower costs. This book is an adaptation of a PhD thesis, which explores this ...

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    21. Progression in Glaucoma (Thesis)

      Progression in Glaucoma (Thesis)

      The treatment of glaucoma is focused on reducing the intraocular pressure to a level at which progression is impeded. A diagnosis of glaucoma is not considered certain until progression is confirmed, and thus detecting progression is a central aspect in both the diagnosing and the monitoring of glaucoma patients. Progression can be identified either through examination of either functional changes in the visual field or structural changes in the retinal nerve fibre layer in the optic disc or in the retina. Optic disc photography, and optical coherence tomography (OCT) that uses laser light, are two methods that are widely used ...

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    22. Measuring coronary artery flow rates using intravascular optical coherence tomography to improve the assessment of percutaneous coronary intervention (Thesis)

      Measuring coronary artery flow rates using intravascular optical coherence tomography to improve the assessment of percutaneous coronary intervention (Thesis)

      In this project, a blood flow quantification technique was developed based on a novel backscattering indicator-dilution approach for intravascular optical coherence tomography (IV-OCT). It achieved the goal of obtaining the flow velocity in a coronary artery of interest by analyzing the backscattering signal from blood after passage of a bolus of Ringer's lactate or another transparent injectate, in parallel to thermodilution coronary flow reserve (CFR). In contrast to thermodilution CFR, the structural OCT image can be used to determine the bolus volume and transit time, as well as used to account for motion and volume change between the two ...

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    23. Investigation of Human Skin Tissues Using Optical Coherence Tomography (Thesis)

      Investigation of Human Skin Tissues Using Optical Coherence Tomography (Thesis)

      Over the decades various imaging technologies have been used for the investigation of skin tissues, but their poor sensitivity, specificity and accuracy limits their applications. In comparison to other imaging modalities, optical coherence tomography (OCT) is a preferred technique as it is a non-invasive imaging modality with a high resolution and is able to perform cellular level imaging as well as providing depth information. This imaging modality has been widely used to image tissues in the human body and thus manifests its potential for clinical applications. Further, OCT can be considered as the potential tool for the identification but the ...

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    24. Characterization of biofouling with 3D-printed spacers using 3D optical coherence tomography (Thesis)

      Characterization of biofouling with 3D-printed spacers using 3D optical coherence tomography (Thesis)

      Biofouling in membrane filtration is a common occurrence which impedes the efficiency of the separation process. By looking into the biofouling mechanisms via the observation of a filtration process, potential problems can be addressed and resolved. This study uses optical coherence tomography (OCT) to investigate the effects of using different 3D-printed spacers on the biofouling process. A compilation of OCT scans of a representative unit cell of each spacer was taken as a function of time to generate 3D-images showing the morphology of a foulant layer. Through the usage of various quantitative analysing methods (such as EIS, DOTM and etc ...

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