1. Articles in category: Student Theses

    1-24 of 121 1 2 3 4 5 »
    1. Automated Three-Dimensional Image Segmentation of Retinal OCT Images (Thesis)

      Automated Three-Dimensional Image Segmentation of Retinal OCT Images (Thesis)

      Optical coherence tomography (OCT) has become an essential tool in ophthalmology. The macular OCT images are three dimensional, high resolution and cross-sectional image of macula, which provides detailed structural information of various macular layers. Moreover macular OCT imaging is non-contact, noninvasive and real-time. OCT images can be obtained quickly and multiple times, this allows easy diagnosis and treatment progress monitoring. With advances in technology acquired dataset size is also increasing, which makes it impractical to manually segment macular layers in clinical environment. Thus need of fast and accurate segmentation algorithm is ever increasing. In this thesis two segmentation algorithms have ...

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    2. High contrast imaging of early demineralization on enamel surfaces using near-infrared polarized reflectance at lambda= 1460 and 1550 nm (Thesis)

      High contrast imaging of early demineralization on enamel surfaces using near-infrared polarized reflectance at lambda= 1460 and 1550 nm (Thesis)

      Introduction: In vivo and in vitro studies have shown that high contrast images of tooth demineralization can be acquired in the near-infrared at several wavelengths. The purpose of this study is to compare the lesion contrast in reflectance at near-infrared wavelengths coincident with high water absorption with those in the visible, the near-infrared at 1300nm, fluorescence, and polarization sensitive optical coherence tomography (PS-OCT) measurements for early lesions on buccal surfaces. Methods: Bovine incisors (n=40) were used in this in vitro study. Teeth were sectioned so that they were greater than 8mm in length, 2mm in width, and had at ...

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      Mentions: UCSF
    3. Handheld Micromanipulator for Robot-Assisted Microsurgery (Thesis)

      Handheld Micromanipulator for Robot-Assisted Microsurgery (Thesis)

      Robot-assisted surgery has been increasingly adopted in a wide variety of surgical applications because it offers fine manipulation with high precision and dexterity. Despite the commercial success of robotic platforms, practical use in microsurgery is still challenging due to a considerable level of accuracy required at sub-millimeter scales. Limited visualization and constrained accessibility also hinder operation under operating microscopes. Furthermore, lack of tactile feedback may lead to substantial and even irrecoverable injury. To address these issues in microsurgery, a handheld micromanipulator, Micron, has been introduced as an alternative to conventional robotic platforms. It allows surgeons to directly maneuver surgical tools ...

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    4. Doppler optical coherence tomography for microcirculation studies (Thesis)

      Doppler optical coherence tomography for microcirculation studies (Thesis)

      This thesis forms part of an ongoing long-term project to investigate the suitability of Doppler optical coherence tomography (OCT) as a measurement tool to investigate skin thickness and blood flow in patients with systemic sclerosis. There is a discussion of the characterisation of an electro-optic phase modulator for use in a Doppler OCT imaging system which is being built for the purpose of clinical studies. In addition to this the development of software for the same system is described. The work includes a comparison of two methods of obtaining Doppler information that were tested with the system; a phase resolved ...

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    5. Optical Coherence Tomography for Neurosurgery and Cancer Research (Thesis)

      Optical Coherence Tomography for Neurosurgery and Cancer Research (Thesis)

      Optical Coherence Tomography (OCT) provides non-labeling, real-time and high resolution images, which has the potential to transform the paradigm of surgical guidance and preclinical animal studies. The design and development of OCT devices for neurosurgery guidance and novel imaging algorithms for monitoring anti-cancer therapy have been pursued in this work. A forward-imaging needle-type OCT probe was developed which can fit into minimally invasive tools (I.D. ~ 1mm), detect the at-risk blood vessels, and identify tissue micro-landmarks. This promising guidance tool improves the safety and the accuracy of needle-based procedures, which are currently performed without imaging feedback. Despite the great imaging ...

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    6. Forward viewing OCT endomicroscopy (Thesis)

      Forward viewing OCT endomicroscopy (Thesis)

      A forward viewing fiber optic-based imaging probe device was designed and constructed for use with ultrahigh speed optical coherence tomography in the human gastrointestinal tract. The light source was a MEMS-VCSEL at 1300 nm wavelength running at 300 kHz sweep rate, giving an effective A-line rate of 600 kHz. Data was acquired with a 1.8 GS/s A/D card optically clocked by a maximum fringe frequency of 1 GHz. The optical beam from the probe was scanned by a freely deflecting optical fiber that was mounted proximally on a piezoelectric tubular actuator, which was electrically driven in two ...

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    7. The qualitative assessment of biodegradable coronary stents with the use of intravascular ultrasound, optical coherence tomography and histology (Thesis)

      The qualitative assessment of biodegradable coronary stents with the use of intravascular ultrasound, optical coherence tomography and histology (Thesis)

      Percutaneous coronary intervention (PCI) is the most common treatment for coronary artery disease (CAD). The first form of PCI introduced was balloon angioplasty. After that, the advent of coronary stents (tubular wire mesh for intravascular mechanical support) led to a new era in interventional cardiology. Through the implantation of bare metal stents (BMS), all three limitations of balloon angioplasty – coronary artery dissection, elastic recoil and negative remodelling – are prevented. Unfortunately, bare metal stents have their own drawbacks: most significantly, in-stent stenosis as a result of deep focal vascular injury caused by stent struts, followed by excessive tissue proliferation. This drawback ...

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    8. Computational Evaluation of Shear Stress and Restenosis in Stented Coronary Arteries Using Optical Coherence Tomography (Thesis)

      Computational Evaluation of Shear Stress and Restenosis in Stented Coronary Arteries Using Optical Coherence Tomography (Thesis)

      The cause of coronary artery neointimal thickness (NT) leading to restenosis in ~10% of drug-eluting stents (DES) is unknown, but adverse wall shear stress (WSS) may contribute. Prior studies comparing WSS to restenosis for first generation DES yielded conflicting results, and cited different mechanisms of action for DES agents. Studies to date have not accounted for stent geometry, which dictates local WSS patterns influencing drug concentration. The objective of this investigation was to evaluate current generation stent platforms via their WSS patterns and their respective impact on NT. We prospectively enrolled 19 patients, who were randomized to thin-strut (81μm ...

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    9. Optical and Photoacoustic Imaging for Ovarian Cancer Detection (Thesis)

      Optical and Photoacoustic Imaging for Ovarian Cancer Detection (Thesis)

      Ovarian cancer is the fifth most common cancer among women and has the highest mortality rate of all gynecologic cancers. Current clinical imaging modalities are limited by poor sensitivity and specificity. Therefore, there is an urgent need to develop effective tools to detect ovarian cancer. In this dissertation, two imaging modalities, optical coherence tomography (OCT) and photoacoustic imaging have been investigated for ovarian cancer detection and characterization. In the first modality, optical scattering coefficient, phase retardation and phase retardation rate were quantitatively extracted from polarization-sensitive OCT (PS-OCT) images. A highly positive correlation was found between those three parameters and collagen ...

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    10. Development of Optical Coherence Tomography for Quantitative Analysis of Cardiac Morphology (Thesis)

      Development of Optical Coherence Tomography for Quantitative Analysis of Cardiac Morphology (Thesis)

      Transgenic mouse models have been instrumental in the elucidation of the molecular mechanism behind many cardiac diseases such as Marfan syndrome. However, the small size of the murine heart has hampered the characterization of its cardiac morphology. In this project, we describe the development of a murine cardiac imaging modality using optical coherence tomography (OCT). After fixation and optical clearing, the hearts were imaged from multiple perspectives. These data sets were then corrected for refraction and registered together to yield a single volume of the whole heart. From this OCT volume, we then applied techniques from computational anatomy to quantify ...

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    11. Share your OCT Thesis on OCT News

      Share your OCT Thesis on OCT News

      OCT News is seeking links to bachelors, masters, and PhD theses in the area of "Optical Coherence Tomography". Traditionally student theses contain a great wealth of information but are rarely accessible to the OCT community. If you or someone you know wrote an OCT thesis and would like to share it with the community please submit a link or PDF using the "Contact OCT News" tab in the main menu bar or the feedback link in the footer and we will include it here: Student Theses. Thesis will only be included if the link is free of charge to users.

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    12. Improved inspection and micrometrology of embedded structures in multi-layered ceramics: Development of optical coherence tomographic methods and tools (Thesis)

      Improved inspection and micrometrology of embedded structures in multi-layered ceramics: Development of optical coherence tomographic methods and tools (Thesis)

      Roll-to-roll manufacturing of micro components based on advanced printing, structuring and lamination of ceramic tapes is rapidly progressing. This large-scale and cost-effective manufacturing process of ceramic micro devices is however prone to hide defects within the visually opaque tape stacks. To achieve a sustainable manufacturing with zero defects in the future, there is an urgent need for reliable inspection systems. The systems to be developed have to perform high-resolution in-process quality control at high speed. Optical coherence tomography (OCT) is a promising technology for detailed in-depth inspection and metrology. Combined with infrared screening of larger areas it can solve the ...

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    13. Adaptive optics optical coherence tomography for in vivo retinal imaging (Thesis)

      Adaptive optics optical coherence tomography for in vivo retinal imaging (Thesis)

      Optical coherence tomography (OCT) is a non-invasive micrometer-resolution volumetric imaging modality that has been employed in diverse applications. In this thesis, we first describe a GPU accelerated program to perform FDOCT data processing and real time 3D volumetric rendering. The real time visualization of volumetric images provided by the GPU acceleration was essential to the rest of the work described in this thesis. Small animal models of retinal diseases serve as a vital component in vision research, and non-invasive in vivo imaging is becoming an increasingly important tool in the field. We describe the first adaptive optics optical coherence tomography ...

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    14. Clinical applications of functional optical coherence tomography (Thesis)

      Clinical applications of functional optical coherence tomography (Thesis)

      The purpose of the work presented in this thesis is to show the potential of functional optical coherence tomography (OCT) to discriminate pathological from normal tissues in several clinical settings, by means of the attenuation coefficient. To that end, several fundamental studies were carried out to increase the fundamental understanding of the measured signals (in phantoms, during apoptosis) and both ex and in vivo investigations are performed in the urological and gynecological clinic.

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    15. In vivo evaluation of neointimal healing after stenting with optical coherence tomography (Thesis)

      In vivo evaluation of neointimal healing after stenting with optical coherence tomography (Thesis)

      Ischemic heart disease is still today the first cause of mortality in the world, especially in the developed countries. The vast majority of cases are due to atherosclerosis, a complex systemic degenerative process resulting in cholesterol accumulation in the extra-cellular space of the arterial intima, with inflammation, foam-cells formation, and necrosis. The clinical manifestations of coronary atherosclerosis comprise from stable angina, due to flow-limiting stenosis of the artery, to acute myocardial infarction or sudden death, when the atheroma gets complicated by thrombotic phenomena. The first revolution in the treatment of this disease came in 1977, when Andreas Grüntzig performed ...

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    16. Angiography and Monitoring of Hemodynamic Signals in the Brain via Optical Coherence Tomography (Thesis)

      Angiography and Monitoring of Hemodynamic Signals in the Brain via Optical Coherence Tomography (Thesis)

      The brain is a complex network of interconnected neurons with each cell functioning as a nonlinear processing unit. Neural responses to stimulus can be described by activity in neurons. While blood flow changes have been associated with neural activity and are critical to brain function, this neurovascular coupling is not well understood. This work presents a technique for neurovascular interrogation, combining optogenetics and optical coherence tomography. Optogenetics is a recently developed neuromodulation technique to control activity in the brain using light with precise spatial neuronal control and high temporal resolution. Using this method, cells act as light-gated ion channels and ...

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    17. Quantification of the neurodegenerative status in patients with multiple sclerosis by optical coherence tomography in respect to functional vision (Thesis)

      Quantification of the neurodegenerative status in patients with multiple sclerosis by optical coherence tomography in respect to functional vision (Thesis)

      Multiple sclerosis is the most frequent, non-traumatic, neurological disorder in young adults in western countries which leads to chronic impairment. The cause of the immune mediated illness remains elusive. Neither clinical nor paraclinical measures can estimate the disability degree or the course of multiple sclerosis (MS). It is crucial to improve the methods which can be a window to the neurodegenerative status of individuals. Structural investigations of the ZNS by MRI own a key position but discriminate between demyelinisation and axonal damage insufficiently and show a discrepancy between lesion load and clinical symptoms. The axonal degeneration goes in line with ...

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    18. The Clinical Application of Optical Coherence Tomography for Head and Neck Premalignant/Malignant Lesions (Thesis)

      The Clinical Application of Optical Coherence Tomography for Head and Neck Premalignant/Malignant Lesions (Thesis)

      Abstract The principle of Optical Coherence Tomography (OCT) is based on the property of light coherence. OCT generates cross-sectional images of two-dimensional objects to obtain in-vitro and in-vivo images of tissues. Non–commercially available OCT systems, which have a higher resolution and scanning rate, have been previously reported. However, some clinical research has already been conducted using the first commercially available OCT device (Niris system) to image the larynx; but applications on oral and skin tissue have not been tested yet. This thesis aims to explore, compare and validate three specific types of commercially available OCT equipment for imaging head ...

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    19. Imaging the Electro-Kinetic Response of Biological Tissues with Optical Coherence Tomography (Thesis)

      Imaging the Electro-Kinetic Response of Biological Tissues with Optical Coherence Tomography (Thesis)

      This thesis reports on developing a novel approach to imaging the electro-kinetic response of biological tissues with optical coherence tomography (OCT). The changes of backscattered OCT signal from tissues were investigated with a low frequency AC electric field being applied to the tissues. Advanced processing algorithms were developed to analyze the amplitude and phase changes of OCT signal. Two-dimensional electrically induced optical changes (EIOC) amplitude and phase images related to the electro-kinetic response of soft tissues were obtained with depth resolution and compared with structural OCT images. The procedure for removing the background noise from EIOC images was introduced.

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    20. The Role of Novel Biophotonic Technique in Characterization of the Newly Developed Nanotechnology based Dental Composites (Thesis)

      The Role of Novel Biophotonic Technique in Characterization of the Newly Developed Nanotechnology based Dental Composites (Thesis)

      [Background and Objective]: Polymerization shrinkage and the associated contraction stresses are the major shortcoming of dental composites in dentistry, which may affect the bonding performance and result in gap formation at the tooth-restoration interface. Non-destructive assessment and monitoring of these defects are critically important. The aim of this study is to assess the toothrestoration interface and composite adaptation using swept source optical coherence tomography (SS-OCT) in combination of microtensile bond strength (MTBS) and to confirm the findings with confocal laser scanning microscope (CLSM) and scanning electron microscopy (SEM). [Materials and Methods]: Standard round class-I cavities were prepared in human premolar ...

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      Mentions: Turki Bakhsh
    21. The design, development and application of a dual-beam spectral-domain optical coherence tomography system for the non-invasive assessment of vascular dynamics by statistical means (Thesis)

      The design, development and application of a dual-beam spectral-domain optical coherence tomography system for the non-invasive assessment of vascular dynamics by statistical means (Thesis)

      This assertion underscores the importance of haematological dynamic assessment, which can benefit greatly from non-invasive high-resolution imaging of blood flow especially at the microvascular level. This importance is further highlighted in oncological applications with recent emphasis on tumour vasculature, angiogenic processes and developments of anti-angiogenic therapies. Optical coherence tomography (OCT) has established itself a firm foothold in the realm of non-invasive optical medical diagnostic imaging, enabling in vivo cross-sectional tomographic visualisation of the internal microstructure of biological systems, and is now considered an optical analogue to CT or MRI, but with microscopic resolution. The original concept of OCT was to ...

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    22. Optical Coherence Tomography as a Characterization Method in Printed Electronics (Thesis)

      Optical Coherence Tomography as a Characterization Method in Printed Electronics (Thesis)

      This Thesis proposes and describes the use of optical coherence tomography (OCT) as a non-contact and non-destructive characterization technique for printed electronics. It is based on and includes the first published results of such an application of the OCT technique. Several different types of structures were studied to evaluate the feasibility of the application. The measurement data was used to define the surface topography, physical dimensions of the specimen features, and to evaluate the ability to characterize multi-layered and multi-material structures. Presented OCT measurements were done for: screen-printed conductive and insulating structures, microfluidic channels, microscopy glass and organic field effect ...

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    23. Integrated-optics-based optical coherence tomography (Thesis)

      Integrated-optics-based optical coherence tomography (Thesis)

      Optical coherence tomography (OCT) is a high resolution, imaging technique that has developed over the last 20 years from a complicated laboratory setup into a ready-to-use commercially available device. Instead of using electronic time gating as being used by ultrasound (US) imaging, in OCT, the optical analogue of US imaging, determines the time of flight using low coherence interferometry. To date, OCT has many clinical applications and is widely used in urology, cardiovascular imaging, dentistry, dermatology and ophthalmology. Currently OCT devices are bulky and expensive, which limits the use of OCT, not only in its existing applications, but also in ...

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    24. Multi-Modality Endoscopic Imaging for the Detection of Colorectal Cancer (Thesis)

      Multi-Modality Endoscopic Imaging for the Detection of Colorectal Cancer (Thesis)

      Optical coherence tomography (OCT) is an imaging method that is considered the optical analog to ultrasound, using the technique of optical interferometry to construct two-dimensional depth-resolved images of tissue microstructure. With a resolution on the order of 10 μm and a penetration depth of 1-2 mm in highly scattering tissue, fiber optics-coupled OCT is an ideal modality for the inspection of the mouse colon with its miniaturization capabilities. In the present study, the complementary modalities laser-induced fluorescence (LIF), which offers information on the biochemical makeup of the tissue, and surface magnifying chromoendoscopy, which offers high contrast surface visualization, are combined ...

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