1. Articles in category: Student Theses

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    1. 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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    2. 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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    3. 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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    4. 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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    5. 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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    6. 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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    7. 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
    8. 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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    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. 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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    11. 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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    12. 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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    13. Characterization and Modeling of an O-Band 1310 nm Sampled-Grating Distributed Bragg Reflector (SG-DBR) Laser for Optical Coherence Tomography (OCT) Applications (Thesis)

      Characterization and Modeling of an O-Band 1310 nm Sampled-Grating Distributed Bragg Reflector (SG-DBR) Laser for Optical Coherence Tomography (OCT) Applications (Thesis)

      In this project, the performance aspects of a new early generation 1310 nm Sampled-Grating Distributed Bragg Reflector (SG-DBR) semiconductor laser are investigated. SG-DBR lasers are ideal for Source Swept Optical Coherence Tomography (SS-OCT), a Fourier-Domain based approach for OCT, necessitating a tunable wavelength source. Three internal sections control the frequency output for tuning, along with two amplifiers for amplitude control. These O-band SG-DBR devices are now being produced in research quantities. SG-DBR lasers have been produced at 1550 and 1600 nm for some times. Fundamental questions regarding the performance of the 1310 nm devices must be quantified. Standard metrics including ...

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      Mentions: Dennis Derickson
    14. Development of Spectral Domain Optical Coherence Tomography for in vivo Functional Imaging of Biological Tissues (Thesis)

      Development of Spectral Domain Optical Coherence Tomography for in vivo Functional Imaging of Biological Tissues (Thesis)

      Optical coherence tomography is a rapidly developing optical imaging modality capable of noninvasively providing depth resolved information of biological tissue at micrometer scale. Since its first report in 1991, it has made tremendous progress leading to successful applications in a number of fields, such as ophthalmology, gastroenterology, dermatology, dentistry, dermatology, cardiology, etc. According to [1], there are more than 15, 000 OCT units that had been put into service in ophthalmic clinic by 2009, which represented approximately $ 1 billion market. The total amount paid by Medicare for OCT scans has increased from $ 1 billion per year in 2001 to $ 7 ...

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    15. Examination of Diagnostic Features in Multiphoton Microscopy and Optical Coherence Tomography Images of Ovarian Tumorigenesis in a Mouse Model (Thesis)

      Examination of Diagnostic Features in Multiphoton Microscopy and Optical Coherence Tomography Images of Ovarian Tumorigenesis in a Mouse Model (Thesis)

      Ovarian cancer is a deadly disease owing to the non-specific symptoms and suspected rapid progression, leading to frequent late stage detection and poor prognosis. Medical imaging methods such as CT, MRI and ultrasound as well as serum testing for cancer markers have had extremely poor performance for early disease detection. Due to the poor performance of available screening methods, and the impracticality and ineffectiveness of taking tissue biopsies from the ovary, women at high risk for developing ovarian cancer are often advised to undergo prophylactic salpingo-oophorectomy. This surgery results in many side effects and is most often unnecessary since only ...

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    16. Ophthalmic engineering: the development of novel instrumentation to further research in the field

      Ophthalmic engineering: the development of novel instrumentation to further research in the field

      The principle theme of this thesis is the advancement and expansion of ophthalmic research via the collaboration between professional Engineers and professional Optometrists. The aim has been to develop new and novel approaches and solutions to contemporary problems in the field. The work is sub divided into three areas of investigation; 1) High technology systems, 2) Modification of current systems to increase functionality, and 3) Development of smaller more portable and cost effective systems. High Technology Systems: A novel high speed Optical Coherence Tomography (OCT) system with integrated simultaneous high speed photography was developed achieving better operational speed than is ...

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    17. Glaucoma diagnostics (Thesis)

      Glaucoma diagnostics (Thesis)

      This thesis addresses several aspects of glaucoma diagnostics from both a clinical and a screening perspective. New instruments for diagnosing glaucoma have been developed over the past years, but little information is available regarding their performance as screening methods and their usefulness in ordinary clinical practice. Purpose of the research underlying this thesis:  The objectives of this research were as follows: to compare the accuracy of results of analysis of the optic nerve head (ONH) achieved by computerized imaging using the Heidelberg Retina Tomograph (HRT) and by subjective assessment performed by physicians with different degrees of experience of glaucoma (paper ...

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    18. A new interventional strategy in complex coronary artery disease: drug-eluting balloons; clinical results and OCT analysis (Thesis)

      A new interventional strategy in complex coronary artery disease: drug-eluting balloons; clinical results and OCT analysis (Thesis)

      In the past decades, major progress has been made in the percutaneous treatment of coronary artery disease. Due to its simplicity and less invasive nature when compared to surgery the number of PCIs grew, while at the same time also the lesion complexity for PCI treatment increased. Despite this increasing number of procedures and the concomitant development of materials and techniques, three important drawbacks are still encountered when performing PCI: 1. Restenosis, 2. Stent thrombosis, and 3. Suitability of a specific device in a certain lesion subset. With regard to restenosis, the transition from balloon angioplasty to bare-metal stenting, and ...

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    19. Quantitative Anterior Segment Optical Coherence Tomography (Thesis)

      Quantitative Anterior Segment Optical Coherence Tomography (Thesis)

      . The optical quality of the human eye is mainly determined by the geometrical and optical properties of two elements, cornea and crystalline lens. The cornea accounts for two-thirds of the optical refractive power, while the crystalline lens provides approximately one third of the total static refractive power of the eye, and it is the responsible for accommodation. Accurate description of the geometry of the eye’s optical components is particularly critical for understanding their contribution to optical aberrations. The geometrical properties of the cornea have been previously studied due to its accessibility. Until recently, knowledge of the geometry of the ...

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    20. Development and application of optical imaging techniques in diagnosing cardiovascular disease (Thesis)

      Development and application of optical imaging techniques in diagnosing cardiovascular disease (Thesis)

      Atherosclerosis and specifically rupture of vulnerable plaques account for 23% of all deaths worldwide, far surpassing both infectious diseases and cancer. Plaque-based macrophages, often associated with lipid deposits, contribute to atherogenesis from initiation through progression, plaque rupture and ultimately, thrombosis. Therefore, the macrophage is an important early cellular marker related to vulnerability of atherosclerotic plaques. The objective of my research is to assess the ability of multiple optical imaging modalities to detect, and further characterize the distribution of macrophages (having taken up plasmonic gold nanoparticles as a contrast agent) and lipid deposits in atherosclerotic plaques. Tissue phantoms and macrophage cell ...

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    21. Speckle Reduction in an All Fiber Time Domain Common Path Optical Coherence Tomography by Frame Averaging (Thesis)

      Speckle Reduction in an All Fiber Time Domain Common Path Optical Coherence Tomography by Frame Averaging (Thesis)

      Optical Coherence Tomography (OCT) is a non-invasive, high resolution morphological imaging modality which has gained significance since its inception in 1992 due to its diversified areas of tissue diagnostics in medical imaging. Time Domain OCT (TDOCT) is one of its simplest commercially viable systems. Image noise in TDOCT has been fundamentally attributed to speckle and most of the commercial algorithms that tackle image noise are predominantly hardware related or utilize complex statistical procedures. Simple frame averaging is a cost effective, post processing algorithm whose effects on TDOCT systems have not been evaluated and hence there was an unmet need forming ...

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      Mentions: Imalux Niris
    22. Spectral-domain optical coherence tomography on a silicon chip (Thesis)

      Spectral-domain optical coherence tomography on a silicon chip (Thesis)

      Optical coherence tomography (OCT) is a non-invasive optical technique for high-resolution cross-sectional imaging of specimens, with many applications in clinical medicine and industry (e.g. materials testing, quality assurance, and process control). Current state-of-the-art OCT systems operate in the frequency domain, using either a broad-band light source and a spectrometer, known as ‘spectral-domain OCT’ (SD-OCT), or a rapidly tunable laser, known as ‘swept-source OCT’ (SS-OCT). Both systems contain a multitude of fiber and free-space optical components which make these instruments costly and bulky. The size and cost of an OCT system can be decreased significantly by the use of integrated ...

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    23. Inline Coherent Imaging (Thesis)

      Inline Coherent Imaging (Thesis)

      In laser materials processing, the direct measurement and characterization of material and process depth is traditionally a diffcult task. This is particularly difficult when such information needs to be obtained in real-time for feedback and dynamic analysis applications. This thesis outlines a novel method and apparatus for real-time depth measurement during laser processes such as welding, drilling, cutting and ablation called inline coherent imaging (ICI). The approach borrows the coherent imaging ideas from the primarily medical field of optical coherence tomography and adapts them to the new application. Without requirements for flawless image quality and limitations on sample exposure the ...

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    24. Segmentation, co-registration, and correlation of optical coherence tomography and X-ray images for breast cancer diagnostics (Thesis)

      Segmentation, co-registration, and correlation of optical coherence tomography and X-ray images for breast cancer diagnostics (Thesis)

      In this thesis, x-ray imaging is evaluated and compared with optical coherence tomography (OCT). It is shown that each individual modality provides information about a sample through different physical characteristics. The preclinical variant of x-ray imaging is explored in the context of breast cancer detection and diagnosis because their clinical use could be augmented by OCT. After comparing them, each modality showed its specialized usage. Micro-CT is useful in detecting microcalcifications, the most apparent target of the screening mammogram. OCT can be utilized in the specific cases where high resolution is desired and penetration depth does not need to be ...

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