1. Articles in category: Student Theses

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    1. The Apply of Spectral Domain Optical Coherence Tomography in Retinal Vessel Assessment of Diabetic Retinopathy (Thesis)

      The Apply of Spectral Domain Optical Coherence Tomography in Retinal Vessel Assessment of Diabetic Retinopathy (Thesis)

      Purpose: To evaluate spectral domain optical coherence tomography (SD-OCT) based methods to differentiate retinal vessel types and measure retinal vessel diameters, and compare these findings with the reference from infrared reflectance (IR) images and/or fluorescein angiography (FA); then, evaluate the retinal vessel diameters in relation to different severity grades of diabetic retinopathy using SD-OCT. Methods: Patients who underwent circular OCT-scans centered at the optic disc with or without non-proliferative diabetic retinopathy (NPDR) were retrospectively reviewed. Individual retinal vessels were identified on IR and given unique labels both on IR and SD-OCT. Vessel types (artery, vein or uncertain) and vessel ...

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    2. Methods to extract and quantify retinal blood vessels and optic nerve head from optical coherence tomography data in neurological disorders (Student Thesis)

      Methods to extract and quantify retinal blood vessels and optic nerve head from optical coherence tomography data in neurological disorders (Student Thesis)

      The eye’s retina is considered to be part of the central nervous system with similar structure and cellular composition like the brain. Thus, it has gained an important role in identifying structural changes that provide useful diagnostic information in many neurological disorders. Over the last decade, innovative advances in optical imaging technology have allowed us to identify these changes in the retinal architecture. Especially optical coherence tomography (OCT) has become a powerful imaging modality in ophthalmology and vision science. OCT non-invasively acquires in micrometer-resolution, three-dimensional (3D), cross-sectional images of biological tissues in vivo, producing in-depth views of the retina ...

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    3. Spectral Domain-optical Coherence Tomography for the Assessment of Cerebrovascular Plasticity (Thesis)

      Spectral Domain-optical Coherence Tomography for the Assessment of Cerebrovascular Plasticity (Thesis)

      Vascular pathologies represent the leading causes of mortality worldwide, accounting for 31% of all deaths in 2012. Cerebral hypoxia is a condition that often manifests as a result of these medical conditions. Remarkably, the nervous system has evolved mechanisms to compensate for oxygen deprivation. The dilation of existing vessels and the growth of new blood vessels are two prominent physiological responses to hypoxia, both of which play a critical role in maintaining cerebral homeostasis. More recently, exercise has been shown to induce a mild state of hypoxia in the brain, leading to several robust morphological changes within the cerebrovascular system ...

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    4. The Optical Coherence Tomography Microsurgical Augmented Reality System (OCT-MARS): A Novel Device for Microsurgeries (Thesis)

      The Optical Coherence Tomography Microsurgical Augmented Reality System (OCT-MARS): A Novel Device for Microsurgeries (Thesis)

      This thesis describes the development and testing of the Optical Coherence Tomography Microsurgical Augmented Reality System (OCT-MARS). This system allows surgeons to view real-time medical image data as an in situ overlay within the surgical field. There are a number of clinical applications for which real time, in situ visualization of otherwise transparent structures of the eye would be beneficial to surgeons. The primary motivating application for this project is the surgical treatment of glaucoma. We have built a projection system capable of producing flat and tilted images in the normal field of view of the microscope with sufficient brightness ...

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    5. Spectrometer-based Optical Coherence Tomography Systems with Extended Functionality (Thesis)

      Spectrometer-based Optical Coherence Tomography Systems with Extended Functionality (Thesis)

      Spectrometer-based Optical Coherence Tomography Systems with Extended Functionality Monteiro Marques, Manuel Jorge (2016) Spectrometer-based Optical Coherence Tomography Systems with Extended Functionality. Doctor of Philosophy (PhD) thesis, University of Kent,. (Access to this publication is currently restricted. You may be able to access a copy if URLs are provided) PDF Restricted to Repository staff only until September 2019. Contact us about this Publication Download (33MB) Abstract Optical coherence tomography (OCT) has evolved over the last two decades to become a major optical imaging modality in the biomedical optics field. By performing high-resolution, multi-dimensional imaging of translucent structures, it enables real-time tissue ...

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    6. High Speed Data Acquisitioni n Swept Source Optical Coherence Tomography

      High Speed Data Acquisitioni n Swept Source Optical Coherence Tomography

      Optical Coherence Tomography (OCT) is an imaging technique especially popular in the medical field, developed to obtain information about the morphology of living biological tissue through cross-sectional images with micrometer resolution. One of the most common applications is the visualization of the eye. In the last decade considerable breakthroughs in this technique have happened, mostly due to the improvement of resolution, sensitivity, dynamic range and acquisition speed. An OCT system is being developed from scratch at IBILI to be used for small animal imaging, namely of the eye. Animals with anatomical resemblance to humans are often used in biomedical research ...

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    7. Planar and Integrated MEMS Micromirrors Based Endoscopic Optical Coherence Tomography (Thesis)

      Planar and Integrated MEMS Micromirrors Based Endoscopic Optical Coherence Tomography (Thesis)

      Optical coherence tomography (OCT) is a thriving imaging modality which provides high-resolution, in vivo, real-time, non-invasive, cross-sectional imaging capability for biomedical applications. Over the past decade, OCT has become a standard clinical diagnosis tool for ophthalmology. However, human organs other than eyeballs are all highly scattering tissues, which limits the OCT penetration depth to ~2 mm. Therefore, endoscopic OCT probes with small diameter must be developed for imaging internal organs. The key component of an endoscopic OCT probe is the optical scanner. Thus, the first objective of this work is to develop miniature optical scanners using microelectromechanical system (MEMS) technology ...

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    8. High-definition optical coherence tomography: Contribution to the non-invasive near infrared optical imaging techniques of the skin (Thesis)

      High-definition optical coherence tomography: Contribution to the non-invasive near infrared optical imaging techniques of the skin (Thesis)

      Background. The development of non-invasive imaging techniques has been stimulated by the shortcomings of histopathology. Currently the only valid diagnostic technique in dermatology is skin biopsy which remains a painful, invasive intervention for the patient. Moreover, this approach is not always convenient for monitoring and follow-up of a skin disease. Optical imaging technologies could solve these shortcomings as they are fast, precise, repeatable and painless. There are four established non-invasive skin imaging techniques used in daily practice: dermoscopy, high-frequency ultrasound, reflectance confocal microscopy (RCM) and conventional optical coherence tomography (C-OCT). In imaging there is a trade-off between resolution and penetration ...

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    9. 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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    10. Swept Source Optical Coherence Tomography Imaging of the Middle Ear Cavity (Thesis)

      Swept Source Optical Coherence Tomography Imaging of the Middle Ear Cavity (Thesis)

      Otitis media (OM), a bacterial infection of the middle ear, is a common pediatric disease. Chronic and recurrent OM is often treated with the surgical placement of tympanostomy tubes in the tympanic membrane (TM), which is the most common reason for pediatric surgery and anesthesia. Antibiotic treatment for chronic OM (COM) is often ineffective, which is explained by the hypothesis that OM is a biofilm-related disease. Recent studies in humans and animals have accumulated evidence for biofilm growth on the middle ear mucosa in COM. However, these studies have required invasive methods to obtain middle ear mucosa samples. Optical Coherence ...

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    11. Development of Swept Source Optical Coherence Tomography and Adaptive Optics Scanning Laser Ophthalmoscopy: Improved Imaging Speed and Handheld Applications (Thesis)

      Development of Swept Source Optical Coherence Tomography and Adaptive Optics Scanning Laser Ophthalmoscopy: Improved Imaging Speed and Handheld Applications (Thesis)

      Optical coherence tomography (OCT) is a noninvasive three-dimensional interferometric imaging technique capable of achieving micrometer scale resolution. It is now a standard of care in ophthalmology, where it is used to improve the accuracy of early diagnosis, to better understand the source of pathophysiology, and to monitor disease progression and response to therapy. In particular, retinal imaging has been the most prevalent clinical application of OCT, but researchers and companies alike are developing OCT systems for cardiology, dermatology, dentistry, and many other medical and industrial applications. Adaptive optics (AO) is a technique used to reduce monochromatic aberrations in optical instruments ...

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      Mentions: Duke University
    12. AUTOMATED MACHINE LEARNING BASED ANALYSIS OF INTRAVASCULAR OPTICAL COHERENCE TOMOGRAPHY IMAGES (Thesis)

      AUTOMATED MACHINE LEARNING BASED ANALYSIS OF INTRAVASCULAR OPTICAL COHERENCE TOMOGRAPHY IMAGES (Thesis)

      Coronary artery disease (CAD) is the leading cause of death in the world. Most acute coronary events (e.g. heart attacks) are due to the rupture of atherosclerotic plaques inside the arteries, however, calcified lesion is the most widely treatable, typically, by stent implantation via percutaneous coronary intervention (PCI). Intravascular Optical Coherence Tomography (IVOCT) imaging has the resolution, contrast, and penetration depth to characterize coronary artery plaques. Conventional manual evaluation of IVOCT images, based on qualitative interpretation of image features, is tedious and time consuming. The aim of this PhD dissertation was to develop advanced algorithms to fully automate the ...

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    13. Attenuation Coefficients, Pixel Intensity, and Texture Analysis as Quantitative Parameters for Analyzing Optical Coherence Tomography Images of Vocal Fold Tissue (Thesis)

      Attenuation Coefficients, Pixel Intensity, and Texture Analysis as Quantitative Parameters for Analyzing Optical Coherence Tomography Images of Vocal Fold Tissue (Thesis)

      Optical coherence tomography is a promising technology to noninvasively assess vocal fold microanatomy. However, many studies using optical coherence tomography to evaluate vocal fold tissue are largely qualitative in nature and lack quantitative measures that might be useful in clinical decision-making. The goal of this thesis was to identify quantitative metrics that can be extracted from optical coherence tomography vocal fold imaging and applied to the surgical subspecialty of Laryngology. The first goal of this study was to determine if optical coherence tomography was sensitive enough to distinguish subtle differences between vocal folds based on vocal fold content using attenuation ...

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    14. Optical coherence tomography Layout Simulation Using MATLAB®

      Optical coherence tomography Layout Simulation Using MATLAB®

      Optical Coherence Tomography (OCT) is a non-invasive optical imaging technique capable of producing 2D images or 3D reconstructions of nonhomogeneous samples. OCT is mainly used in ophthalmology as a powerful tool for the early diagnosis of ocular diseases. With OCT it is possible to obtain high resolution cross-sectional images of ocular structures, such as the retina or the anterior segment. An OCT platform for ocular image acquisition is being developed. It is based on a swept source laser, an InGaAs balanced detector, a data acquisition board installed on a personal computer, and several optical components. The main purpose of this ...

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    15. Acoustic Radiation Force Optical Coherence Elastography : Localized Vs. Wide-Area Perturbation – A Comparison (Thesis)

      Acoustic Radiation Force Optical Coherence Elastography : Localized Vs. Wide-Area Perturbation – A Comparison (Thesis)

      Elastography is a method to image the biomechanical properties of tissues. The experimental setup has a 10 MHz ultrasound transducer (focal length of 5cm and a spot size of 0.3mm localized excitation and unfocused for wide-area excitation) which generates acoustic radiation force (ARF) to perturb the sample and the corresponding mechanical response is imaged with a spectral domain optical coherence tomography (SD-OCT) with a center wavelength of 800 nm and a bandwidth of 180 nm at a transverse optical resolution of 8[mu]m. The existing hypothesis which states that localized harmonic excitation in audio frequency regime has potential ...

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    16. Advanced Monte Carlo Simulation and Machine Learning for Frequency Domain Optical Coherence Tomography

      Advanced Monte Carlo Simulation and Machine Learning for Frequency Domain Optical Coherence Tomography

      Optical Coherence Tomography(OCT) is a popular, rapidly growing imaging technique with an increasing number of bio-medical applications due to its noninvasive nature. However, there are three major challenges in understanding and improving an OCT system: (1) Obtaining an OCT image is not easy. It either takes a real medical experiment or requires days of computer simulation. Without much data, it is difficult to study the physical processes underlying OCT imaging of different objects simply because there aren't many imaged objects. (2) Interpretation of an OCT image is also hard. This challenge is more profound than it appears. For ...

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    17. Development of spectral domain optical coherence tomography for pharmaceutical and medical application

      Development of spectral domain optical coherence tomography for pharmaceutical and medical application

      Spectral-domain optical coherence tomography (SD-OCT) is a type of non-destructive imaging technique that is capable of resolving the inner structure of a sample with micrometre spatial resolution. SD-OCT is based on low coherence interferometry. It utilises a spectrometer to grab the spectral interferogram between the back reflected/scattered light from a reference mirror and a sample. The depth profile, which carries the sample inner structure information, is then generated by a data interpolation and Fourier Transform (FT). Functional coating of solid oral dosage forms optimises the release profile of active pharmaceutical ingredient (API) and results in a desirable API absorption ...

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    18. Characterising the effect of a novel optical delay line and light sources on the resolvability of time domain optical coherence tomography (Thesis)

      Characterising the effect of a novel optical delay line and light sources on the resolvability of time domain optical coherence tomography (Thesis)

      Optical coherence tomography (OCT) is a reflection based imaging technique, with numerous applications, initially in medical diagnostics. Unlike ultrasound, another reflection imaging technique, OCT relies on light scattering in samples, low coherence near- infrared interferometry, and graphical image construction, to acquire 2D and 3D reflectogram images. OCT has resolution an order of magnitude greater than ultrasound, but its depth penetration is less than a few millimetres. Axial resolution is a critical parameter in determining whether OCT can be used to resolve specific features in a sample image. Typically, measures of resolution have been attributed only to the light source’s ...

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    19. Restoration of optical coherence tomography images using stochastic methods (Thesis)

      Restoration of optical coherence tomography images using stochastic methods (Thesis)

      Optical coherence tomography (OCT) is a rapidly growing imaging modality that produces high resolution three dimensional images that can be applied to different medical and industrial applications . Obtaining higher depth of imaging and higher imaging quality are important goals in OCT systems. One of the main factors that affects the penetration depth and imaging quality of OCT systems is the presence of noise. The depth-scan photocurrent of time domain (TD) OCT system is degraded by a class of correlated and signal dependent noise. The joint probability density function of the depth-scan photocurrent can be considered as Gaussian random process that ...

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    20. Heartbeat Optical Coherence Tomography (Thesis)

      Heartbeat Optical Coherence Tomography (Thesis)

      Coronary artery disease (CAD) is a manifestation of atherosclerosis, a systemic inflammatory disease of the arteries that causes the formation of plaques in the artery walls. Different plaques may give rise to different symptoms: a gradual narrowing (stenosis) of the vessel by growth of a fibrous or calcific plaque will cause chest pain (due to cardiac ischemia) upon exertion, a condition called stable CAD. Sudden onset of chest pain, or chest pain at rest, is a symptom of unstable CAD or acute coronary syndrome (ACS), which is associated with thrombus formation on plaques, mostly due to rupture of a lipid-core ...

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    21. Development of a Retinal Eye Tracker for 3D Optical Coherence Tomography (Thesis)

      Development of a Retinal Eye Tracker for 3D Optical Coherence Tomography (Thesis)

      Several eye diseases appear in the posterior part of the eye, i.e. the retina or fundus. Retinal images therefore provide valuable information to identify eye diseases. Optical Coherence Tomography (OCT) is a 3D imaging technique that can image the retina with a resolution and depth penetration that can not be achieved by any other non-invasive imaging technique. Although OCT can achieve high resolution, in vivo measurements are severely limited by eye motion. TNO developed a low-cost eye tracker with improved eye motion tracking compared to current state of the art eye trackers. The eye tracker images the retina at ...

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    22. Ultra-widefield optical coherence tomography of the human retina (Thesis)

      Ultra-widefield optical coherence tomography of the human retina (Thesis)

      Optical coherence tomography (OCT) has become a standard of care in ophthalmology since it was first demonstrated over 20 years ago. Images acquired using commercial OCT systems have been reported to have a maximum imaging length of only 9 mm, which is equivalent to an internal-field of view of 45◦. This narrow-field limitation has been acceptable because of the high level of clinical data available in the macular region and the relative simplicity of imaging this area of the retina. Commercially-available scanning laser ophthalmoloscope (SLO) systems such as the Optos 200Tx are capable of providing a fundus image with an ...

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    23. Evaluation of the Crystalline Lens Gradient Refractive Index using Laser Ray Tracing and Optical Coherence Tomography (Thesis)

      Evaluation of the Crystalline Lens Gradient Refractive Index using Laser Ray Tracing and Optical Coherence Tomography (Thesis)

      The human crystalline lens is a complex and intricate structure that continuously grows throughout our lifetime. The crystalline lens has a non-uniform distribution of protein concentrations which produces an optical gradient within the lens in both the optical and equatorial axes. This gradient refractive index is a unique property of the crystalline lens that significantly contributes to its optical power and aberrations. The objective of this dissertation is to gain a better understanding of the relationship between the crystalline lens shape, its non-uniform gradient refractive index, the lens optical power and aberrations, and their changes with accommodation and age. The ...

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    24. An Evaluation of Silicon Carbide Based Bimorph Actuators for Optical Coherence Tomography Applications

      An Evaluation of Silicon Carbide Based Bimorph Actuators for Optical Coherence Tomography Applications

      Optical coherence tomography (OCT) probes rely on MEMS micro-scanners to provide fast and reproducible scans covering as much area as possible. A popular choice of actuators employed in this role are electrothermal bimorph actuators. They comprise of two layers of different materials which are rigidly joined together. Differential expansion under heating causes the bimorph to deflect. Polycrystalline silicon carbide has been proposed to replace polysilicon as a multi-purpose material in MEMS but it has not been yet explored as a bimorph material. Under this premise, an in-plane bimorph actuator based on doped polycrystalline silicon carbide and silicon was proposed to ...

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