1. Articles in category: Student Theses

    217-240 of 272 « 1 2 ... 7 8 9 10 11 12 »
    1. Novel Biomedical Imaging Systems (Thesis)

      Novel Biomedical Imaging Systems (Thesis)
      The overall purpose of the dissertation is to design and develop novel optical imaging systems that require minimal or no mechanical scanning to reduce the acquisition time for extracting image data from biological tissue samples. Two imaging modalities have been focused upon: a parallel optical coherence tomography (POCT) system and a volume holographic imaging system (VHIS). Optical coherence tomography (OCT) is a coherent imaging technique, which shows great promise in biomedical applications. A POCT system is a novel technology that replaces mechanically transverse scanning in the lateral direction with electronic scanning. This will reduce the time required to acquire image ...
      Read Full Article
    2. Image Processing and Clinical Applications of Anterior Segment Optical Coherence Tomography (Thesis)

      Image Processing and Clinical Applications of Anterior Segment Optical Coherence Tomography (Thesis)
      Optical coherence tomography (OCT) is an emerging imaging modality. It provides in vivo cross-sectional images with micron level resolution. OCT is attractive for imaging the anterior eye segment because of its characteristics on high resolution, non-contact, and easy anatomical interpretation. The fast data acquisition rate (>2000 axial scans per second) of current anterior segment OCT systems allows the measurement of corneal dimensions without significant motion error. It also generates huge amount of data. Manual anatomic reconstruction and measurement are time consuming and operator-dependent. Automated image processing and analysis techniques can overcome these limitations and make routine clinical use of OCT ...
      Read Full Article
    3. 1.2-Micron Multi-Section Quantum Dot Superluminescent Diodes (Thesis)

      1.2-Micron Multi-Section Quantum Dot Superluminescent Diodes (Thesis)
      Superluminescent diodes (SLD) with a center wavelength of 1.2µm are of interest for use in medical imaging of skin tissue especially in the field of optical coherence tomography (OCT). In this thesis a ridge-waveguide multi-section quantum dot SLD that emits at 1.2µm with a bandwidth greater than 100nm and a power greater than 0.2mW is presented. The multi-section SLD allows simultaneous tuning of the ground state emission and excited state emission, resulting in wide bandwidth and high power. Theoretical equations describing the intensity output of the multi-section SLD configuration are presented. It is found that these equations ...
      Read Full Article
    4. Development of Fourier Domain Optical Coherence Tomography for Applications in Developmental Biology (Thesis)

      Development of Fourier Domain Optical Coherence Tomography for Applications in Developmental Biology (Thesis)
      Developmental biology is a field in which explorations are made to answer how an organism transforms from a single cell to a complex system made up of trillions of highly organized and highly specified cells. This field, however, is not just for discovery, it is crucial for unlocking factors that lead to diseases, defects, or malformations. The one key ingredient that contributes to the success of studies in developmental biology is the technology that is available for use. Optical coherence tomography (OCT) is one such technology. OCT fills a niche between the high resolution of confocal microscopy and deep imaging ...
      Read Full Article
    5. Phase-sensitive light: coherence theory and applications to optical imaging (Thesis)

      Phase-sensitive light: coherence theory and applications to optical imaging (Thesis)
      Spontaneous parametric downconversion (SPDC) can produce pairs of entangled photons, i.e., a stream of biphotons. SPDC has been utilized in a number of optical imaging applications, such as optical coherence tomography, ghost imaging, holography and lithography, to obtain performance that cannot be realized with standard optical sources. However, a debate continues as to whether the improved imaging characteristics of such systems should be attributed to the entanglement property of the photon pairs. This thesis sets out to unify--and generalize--classical and quantum imaging within the framework of Gaussian-state light fields, which encompasses thermal light--the source used in conventional imagers--and biphoton-state ...
      Read Full Article
    6. A Study of Computer Vision and Pattern Recognition in Medical Image Analysis: Digital Microscopy and Optical Coherent Tomography (Thesis)

      A Study of Computer Vision and Pattern Recognition in Medical Image Analysis: Digital Microscopy and Optical Coherent Tomography (Thesis)
      Computer vision and pattern recognition techniques have been fostered to solve many practical problems of diverse areas. Medical image analysis using machine vision and learning intelligence is one of the most sought-after fields. Computer vision addresses problems of the use of computers to detect, partition, represent, group, track, and interpret crucial primitives from given visual inputs. By contrast, pattern recognition is the study of distinguishing and recognizing different patterns represented with quantitative measurements. As a result, both of these two components usually present themselves in medical image analysis research work. In this dissertation, two parts of new theoretical work and ...
      Read Full Article
    7. High-speed Fourier domain Optical Coherence Tomography for structural and functional imaging of the retina (Thesis)

      High-speed Fourier domain Optical Coherence Tomography for structural and functional imaging of the retina (Thesis)
      Optical Coherence Tomography (OCT) is an emerging optical biomedical imaging technology that enables cross-sectional imaging of scattering tissue with high sensitivity and micron-scale resolution. In conventional OCT, the reference arm path length in a Michelson interferometer is scanned in time to generate a profile of backscattering versus depth from the sample arm. In conventional OCT, a broadband, low coherence light source is used to achieve high axial resolution. However, clinical and research applications of conventional OCT have been limited by low imaging speeds. Recently, new Fourier domain OCT detection methods have enabled speeds of ~20,000-40,000 axial scans per ...
      Read Full Article
    8. Advances in Optical Coherence Tomography and Microscopy for endoscopic applications and functional neuroimaging (Thesis)

      Advances in Optical Coherence Tomography and Microscopy for endoscopic applications and functional neuroimaging (Thesis)
      Optical Coherence Tomography (OCT) is a developing medical imaging technology that generates micron resolution cross-sectional images of subsurface internal tissue structure in situ and in real time, without the need to remove and process specimens. Previous studies have suggested that OCT holds great potential for use in laparoscopic and endoscopic applications to detect early stage neoplastic pathologies. A minimally invasive imaging modality capable of identifying pre-malignant tissues in vivo could be used to guide conventional excisional biopsy and histology, thereby reducing sampling error and enabling earlier detection and treatment. One limitation of prior endoscopic OCT imaging methods is the inability ...
      Read Full Article
    9. New technologies for optical coherence microscopy (Thesis)

      New technologies for optical coherence microscopy (Thesis)
      According to the American Cancer Society, gastrointestinal (GI) cancers are among the most common forms of malignancies suffered today, affecting -200,000 people and causing -80,000 deaths in the United States every year. The prognosis depends heavily on the detection of early-stage lesions. The process of endoscopic surveillance, excisional biopsy, and histologic examination is the current gold standard for screening and diagnosis of many GI cancers. This process, however, is invasive, time-consuming, and can suffer from unacceptable false negative rates. Optical imaging technology that provides real-time, high-resolution imaging of human tissue in vivo with resolution at or near that ...
      Read Full Article
    10. Imaging Tissue Engineered Blood Vessel Mimics with Optical Coherence Tomography (Thesis)

      Imaging Tissue Engineered Blood Vessel Mimics with Optical Coherence Tomography (Thesis)
      Optical coherence tomography (OCT) is a technology that enables 2D cross-sectional images of tissue microstructure. This interferometric technique provides resolutions of approximately 10-20 um with a penetration depth of 1-2 mm in highly scattering tissues. With the use of fiber optics, OCT systems have been developed for intravascular imaging with a demonstrated improvement in both resolution and dynamic range compared to commercial intravascular ultrasound systems. OCT studies of normal, atherosclerotic, and stented arteries indicate the ability of OCT to visualize arterial structures. These results suggest OCT may be a valuable tool for studying luminal structures in tissue engineered constructs. In ...
      Read Full Article
    11. Spectral Analysis of Optical Coherence Tomography Signals (Thesis)

      Spectral Analysis of Optical Coherence Tomography Signals (Thesis)

      More than 85% of all cancers originate in the epithelium that lines the internal surfaces of organs throughout the body. Before they become invasive, at stages known as dysplasia and carcinoma in situ, early cancer cells alter the epithelial-cell architecture. More specially, the number of cells, and therefore the number ofnuclei, increases. The nuclei themselves become enlarged and hyperchromatic, i.e. their chromatin changes and colours more darkly when stained during histopathology. Nuclear sizes change from the normal 5 - 10 um to 1:5 - 2 x the size, i.e.10 - 20 um. Currently, these early changes are only detectable ...

      Read Full Article
    12. Computer-Aided Diagnosis of Early Cancers in the Gastrointestinal Tract Using Optical Coherence Tomography (Thesis)

      Computer-Aided Diagnosis of Early Cancers in the Gastrointestinal Tract Using Optical Coherence Tomography (Thesis)
      Optical coherence tomography (OCT) is an emerging optical technique based on low-coherence interferometry that provides noninvasive, subsurface, high-resolution imaging of biological microstructure. Endoscopic OCT (EOCT) differentiates the tissue layers of the gastrointestinal (GI) wall and can identify dysplasia in the mucosa. The objective of this research was the characterization of dysplasia in the GI tract, by EOCT in Barretts esophagus in the upper GI tract and by OCT in colonic crypts in the lower GI tract. Barretts esophagus (BE) and associated adenocarcinoma have emerged as a major health care problem over the last two decades. We developed computer-aided diagnosis (CAD ...
      Read Full Article
    13. Ultra High Resolution and Contrast Sensitive Optical Coherence Tomography (Thesis)

      Ultra High Resolution and Contrast Sensitive Optical Coherence Tomography (Thesis)
      In this thesis, I first demonstrate three novel broad band light sources at above 1 µm for ultra-high resolution optical coherence tomography (OCT) based on multiple SLED combination and supercontinuum generation. The light sources are compact, reliable, smooth and ready for practical applications. The images achieved with those light sources showed superior quality in comparison to the images achieved under normal resolution OCT with axial resolution around 12 to 15 µm. In the second part of the thesis, the feasibility of using gold nanorod (NR) as a probe for contrast sensitive OCT is described. Two methods, photothermal effect (PT) and ...
      Read Full Article
    14. Imaging the Embryonic Heart with Optical Coherence Tomography (Thesis)

      Imaging the Embryonic Heart with Optical Coherence Tomography (Thesis)
      Abnormalities that occur during cardiac looping in the early embryo are responsible for congenital heart disease. To date researchers have had to rely upon bioassays, video microscopy and mathematical models to investigate the mechanisms underlying development during looping. Direct observation of looping has been problematic due to the diminutive size (< 2 mm) of the heart and the inability to measure the small and rapid events that influence heart development. Optical coherence tomography (OCT) is a noninvasive imaging tool with the spatiotemporal resolution and field of view to observe both structure and function during the critical time period of looping. Here ...
      Read Full Article
    15. Optical coherence tomography of strongly scattering media (Thesis)

      Optical coherence tomography of strongly scattering media (Thesis)
      Optical coherence tomography (OCT) is a modern rapidly developing technique for non-invasive imaging of the internal structure of optically non-uniform objects based on the principles of lowc oherent interferometry. However, multiple scattering of light in the objects under study brings distortions to the images obtained by OCT. The analysis of formation of the OCT signals is required for understanding the role of multiple scattering in this formation and providing recommendations for optimal configuration of a measuring setup. In the present thesis formation of the OCT signals and images is analyzed implementing Monte Carlo simulations of light propagation in scattering media ...
      Read Full Article
    16. Spectral-domain optical coherence phase microscopy for quantitative biological studies (Thesis)

      Spectral-domain optical coherence phase microscopy for quantitative biological studies (Thesis)
      Conventional phase-contrast and differential interference contrast microscopy produce high contrast images of transparent specimens such as cells. However, they do not provide quantitative information or do not have enough sensitivity to detect nanometerlevel structural alterations. We have developed spectral-domain optical coherence phase microscopy (SD-OCPM) for highly sensitive quantitative phase imaging in 3D. This technique employs common-path spectral-domain optical coherence reflectometry to produce depth-resolved reflectance and quantitative phase images with high phase stability. The phase sensitivity of SD-OCPM was measured as nanometer-level for cellular specimens, demonstrating the capability for detecting small structural variation within the specimens. We applied SD-OCPM to the ...
      Read Full Article
    17. Ultrahigh-Resolution Endoscopic Optical Coherence Tomography for In Vivo Mouse Colonoscopy (Thesis)

      Ultrahigh-Resolution Endoscopic Optical Coherence Tomography for In Vivo Mouse Colonoscopy (Thesis)
      In vivo monitoring of mouse models of colon cancer promises to reduce the cost of research by improving sacrifice timing and allowing serial studies that observe the progression of disease and drug efficacy in a relatively small set of animals. Optical coherence tomography (OCT) is an optical analog of ultrasound imaging, capable of minimally-invasive mapping of light scatter intensity up to 2 mm deep in tissue. In this work, factors limiting resolution in OCT were examined and devices were created and applied to mouse colon imaging that extended the state-of-the-art in endoscopic ultrahigh-resolution OCT. First, axial chromatic aberration of the ...
      Read Full Article
    18. Phase-locked Fourier domain optical coherence tomography (Thesis)

      Phase-locked Fourier domain optical coherence tomography (Thesis)

      Fourier or spectral domain optical coherence tomography (FDOCT) is a multi-dimensional interferometric imaging modality that has attracted increasing interest during the last few years. The reason is its outstanding sensitivity allowing high speed 2D and 3D imaging of weakly backscattering biological tissues in vivo and with high axial resolution. FDOCT has today largely replaced the preceding time domain OCT due to its marked advantage in sensitivity and acquisition speed. In particular, for fast in vivo retinal imaging with high resolution in 3D, FDOCT has become the method of choice. Recent developments enhance the clinical and biomedical potential of FDOCT by ...

      Read Full Article
    19. Evaluation of Mouse Models of Colorectal Cancer Using Optical Coherence Tomography and Laser Induced Fluorescence Spectroscopy (Thesis)

      Evaluation of Mouse Models of Colorectal Cancer Using Optical Coherence Tomography and Laser Induced Fluorescence Spectroscopy (Thesis)
      Colorectal cancer (CRC) is the third leading cause of cancer related deaths. Rodent models of CRC are useful for evaluating diagnostic tools, therapeutics, and disease progression; however, an appropriate imaging tool is needed. Optical coherence tomography (OCT) is a non-destructive imaging modality readily packaged into small diameter endoscopes. Using a near- infrared light source, structural images are generated from index of refraction mismatches with resolutions of 2-15 mm at imaging depths of up to 1.3 mm. In contrast, laser-induced fluorescence (LIF) spectroscopy provides information about biochemical composition, exciting tissues with ultraviolet to green wavelengths of light to measure fluorescence ...
      Read Full Article
    20. Motion contrast using optical coherence tomography (Thesis)

      Diagnosis of ophthalmic diseases like age-related macular degeneration is very important for treatment of the disease as well as the development of future treatments. Optical coherence tomography (OCT) is an optical interference technique which can measure the three-dimensional structural information of the reflecting layers within a sample. In retinal imaging, OCT is used as the primary diagnostic tool for structural abnormalities such as retinal holes and detachments. The contrast within the images of this technique is based upon reflectivity changes from different regions of the retina. This thesis demonstrates the developments of methods used to produce additional contrast to the ...
      Read Full Article
    21. Microstructural information beyond the resolution limit: studies in two coherent, wide-field biomedical imaging systems (Thesis)

      Microstructural information beyond the resolution limit: studies in two coherent, wide-field biomedical imaging systems (Thesis)
      In this thesis, we describe and analyse the characteristics of two different coherence optical microscopic imaging modalities, with a particular emphasis on their principles of operation and their respective resolution limits. By coherent, we mean that each detects a signal on an optical field basis; they are therefore sensitive to both the amplitude and phase of the light detected after interaction with a sample. This information is obtained interferometerically, by isolating the cross-term associated with detecting the intensity (squared modulus) of the sum of the sample field and a coherent reference wave. Both modalities have advanced rapidly in the last ...
      Read Full Article
    22. Optical method for liquid sorption measurements in paper (Thesis)

      Optical method for liquid sorption measurements in paper (Thesis)
      This thesis presents an effective optical method for measuring liquid sorption into paper. From the two tested methods, based on a streak-camera and optical coherence tomography (OCT), the last-mentioned proved very promising for investigating dynamical paper-liquid interactions as spatially and temporally dependent processes. The streak-camera measurements were performed to explore the relationship between paper properties and light migration in dry and refractive index matched paper in general. Based on streak-camera measurements, a novel procedure for determining the average refractive index of cellulose fibre tissue was also presented here. In addition, the streak camera method lent itself to paper porosity determination ...
      Read Full Article
    23. Enhancement of contrast in optical coherence tomography: new modes, methods and technology (Thesis)

      Enhancement of contrast in optical coherence tomography: new modes, methods and technology (Thesis)
      This thesis is concerned with exploiting the native optical coherence tomography (OCT) contrast mechanism in new ways and with a new contrast mechanism, in both cases to enhance the information content of the tomographic image. Through experiments in microsphere solutions, we show that static speckle contains information about local particle density when the effective number of scatterers in the OCT resolution volume is less than about five. This potentially provides contrast enhancement in OCT images based on local scatterer density, and we discuss the experimental conditions suited to utilising this in biological tissue. We also describe the corrupting effects of ...
      Read Full Article
    24. Optical Coherence Tomography Of Oral Mucosa (Thesis)

      Optical Coherence Tomography Of Oral Mucosa (Thesis)
      Oral cancer causes 120000* deaths annually around the world and 280000* new cases are diagnosed every year. Technology has developed and the death rate of oral cancer has improved over the last few decades; hence to improve the survival rate, development of a technique able to diagnose carcinomas in its early stages is very important. OCT is a non invasive imaging technique capable to provide high resolution microstructure images of tissue. A development of in vivo OCT; capable to image tissue with micrometer resolution and able to identify pre cancerous morphological changes non invasively could improve survival rate in cancer ...
      Read Full Article
    217-240 of 272 « 1 2 ... 7 8 9 10 11 12 »
  1. Categories

    1. Applications:

      Art, Cardiology, Dentistry, Dermatology, Developmental Biology, Gastroenterology, Gynecology, Microscopy, NDE/NDT, Neurology, Oncology, Ophthalmology, Other Non-Medical, Otolaryngology, Pulmonology, Urology
    2. Business News:

      Acquisition, Clinical Trials, Funding, Other Business News, Partnership, Patents
    3. Technology:

      Broadband Sources, Probes, Tunable Sources
    4. Miscellaneous:

      Jobs & Studentships, Student Theses, Textbooks
  2. Popular Articles

  3. Organizations in the News

    1. (1 articles) Academic Medical Center at the University of Amsterdam
    2. (1 articles) Duke University
    3. (1 articles) University of Twente
    4. (1 articles) Delft University of Technology
    5. (1 articles) Northwestern University
    6. (1 articles) University of North Carolina
    7. (1 articles) University of Toronto
  4. People in the News

    1. (1 articles) Mark Draelos