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Registration of radiotherapy images using multiscale medial descriptions of image structure [microform] /

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Thesis (Ph. D.)--University of North Carolina at Chapel Hill, 1993. " ... in partial fulfillment of the requirements for the degree of Doctor of Philosophy in the Department of Biomedical Engineering." Includes bibliographical references (leaves: 303-309). Microfiche. s

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In computational imaging, data acquired by sampling the same scene or object at different times or from different orientations result in images in different coordinate systems. Registration is a crucial step in order to be able to compare, integrate and fuse the data obtained from different measurements. Tomography is the method of imaging a single plane or slice of an object. A Computed Tomography (CT) scan, also known as a CAT scan (Computed Axial Tomography scan), is a Helical Tomography, which traditionally produces a 2D image of the structures in a thin section of the body. It uses X-ray, which is ionizing radiation. Although the actual dose is typically low, repeated scans should be limited. In dentistry, implant dentistry in specific, there is a need for 3D visualization of internal anatomy. The internal visualization is mainly based on CT scanning technologies. The most important technological advancement which dramatically enhanced the clinician's ability to diagnose, treat, and plan dental implants has been the CT scan. Advanced 3D modeling and visualization techniques permit highly refined and accurate assessment of the CT scan data. However, in addition to imperfections of the instrument and the imaging process, it is not uncommon to encounter other unwanted artifacts in the form of bright regions, flares and erroneous pixels due to dental bridges, metal braces, etc. Currently, removing and cleaning up the data from acquisition backscattering imperfections and unwanted artifacts is performed manually, which is as good as the experience level of the technician. On the other hand the process is error prone, since the editing process needs to be performed image by image. We address some of these issues by proposing novel registration methods and using stonecast models of patient's dental imprint as reference ground truth data. Stone-cast models were originally used by dentists to make complete or partial dentures. The CT scan of such stone-cast models can be used to automatically guide the cleaning of patients' CT scans from defects or unwanted artifacts, and also as an automatic segmentation system for the outliers of the CT scan data without use of stone-cast models. Segmented data is subsequently used to clean the data from artifacts using a new proposed 3D inpainting approach.
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Thesis (Ph. D.)--University of North Carolina at Chapel Hill, 2004. Includes bibliographical references (leaves 138-147). Microfiche. s
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Introduction Non-linear diffusion or Variable Conductance Diffusion (VCD) processes can be used as to filter away noise while preserving boundary information. However, adjustment of the control parameters is not well understood. By approaching the control of VCD systems through a multiscale statistical analysis, information about the image is revealed regarding the strength of boundaries and their influence with regard to the local geometry of the object. This information can then be used to monitor and guide the diffusion process. Background Several approachs to computer vision begin with a set of governing constraints and equations, and construct the mathematics and superstructure for vision based upon these axiomatic principles. One such approach toward vision is based upon diffusion as a plausible model of vision. Grossberg describes a model that includes a boundary detection system and a system by which feature values undergo a process of "filling-in" [Gro
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