AN AUTOMATED DENTAL CARIES DETECTION AND SCORING SYSTEM FOR OPTIC IMAGES OF TOOTH OCCLUSAL SURFACE

Dental caries are one of the most prevalent chronic diseases. Worldwide 60 to 90 percent of school children and nearly 100 percent of adults experienced dental caries. The management of dental caries demands detection of carious lesions at early stages. The research of designing diagnostic tools in caries has been at peak for the last decade. This research aims to design an automated system to detect and score dental caries according to the International Caries Detection and Assessment System (ICDAS) guidelines using the optical images of the occlusal tooth surface. There have been numerous works that address the problem of caries detection by using new imaging technologies or advanced measurements. However, no such study has been done to detect and score caries with the use of optical images of the tooth surface. The aim of this dissertation is to develop image processing and machine learning algorithms to address the problem of detection and scoring the caries by the use of optical image of the tooth surface

Doctor of Philosophy

dissertationMost neighboring stars are still detected as point sources and are beyond the angular resolution reach of current observatories. Methods to improve our understanding of stars at high angular resolution are investigated. Air Cherenkov telescopes (ACTs), primarily used for Gamma-ray astronomy, enable us to increase our understanding of the circumstellar environment of a particular system. When used as optical intensity interferometers, future ACT arrays will allow us to detect stars as extended objects and image their surfaces at high angular resolution. ACTs are used in gamma-ray astronomy to investigate violent phenomena in the universe. However, this technique can also be used for stellar astrophysics on some isolated sources. Such is the case with the X-ray binary LS I +61◦303 which was detected in the TeV range. A gamma-ray attenuation model is developed and applied to this system. This models allows us to place constraints on fundamental properties of the system. However, a much better understanding of this system, and more so of nearby bright stellar systems, could be obtained with high angular resolution techniques. Optical stellar intensity interferometry (SII) with ACT arrays, composed of nearly 100 telescopes, will provide means to measure fundamental stellar parameters and also open the possibility of model-independent imaging. A data analysis algorithm is developed and permits the reconstruction of high angular resolution images from simulated SII data. The capabilities and limitations of future ACT arrays used for high angular resolution imaging are investigated via Monte-Carlo simulations. Simple stellar objects as well as stellar surfaces with localized hot or cool regions can be accurately imaged. Finally, experimental efforts to measure intensity correlations are expounded. The functionality of analog and digital correlators is demonstrated. Intensity correlations have been measured for a simulated star emitting pseudo-thermal light, resulting in angular diameter measurements. The StarBase observatory, consisting of a pair of 3m telescopes separated by 23m, is described

Optical Diffraction Tomography for Single Cells

Analyzing the structure of a single cell based on its refractive index (RI) distribution is a common and valued approach, because it does not require any artificial markers. The RI is an inherent structural marker that can be quantified in three dimensions with optical diffraction tomography (ODT), an inverse scattering technique. This work reviews the theory of ODT and its implementation with an emphasis on single-cell analysis, identifying the Rytov approximation as the most efficient descriptor for light propagation. The accuracy of the reconstruction method is verified with in silico data and imaging artifacts associated with the inverse scattering approach are addressed. Furthermore, an experimental ODT setup is presented that consists of a bright-field microscope, a phase-imaging camera, and an optical trap combined with a microfluidic chip. A novel image analysis pipeline is proposed that addresses image corrections and frame alignment of the recorded data prior to the RI reconstruction. In addition, for a rotational axis that is tilted with respect to the image plane, an improved reconstruction algorithm is introduced and applied to single, suspended cells in vitro, achieving sub-cellular resolution