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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
21

A supervised learning framework for multi-modal rigid registration with applications to angiographic images /

Chan, Ho-Ming. January 2003 (has links)
Thesis (M. Phil.)--Hong Kong University of Science and Technology, 2003. / Includes bibliographical references (leaves 60-62). Also available in electronic version. Access restricted to campus users.
22

Feature-based 2D-3D registration and 3D reconstruction from a limited number of images via statistical inference for image-guidedinterventions

Kang, Xin, 康欣 January 2011 (has links)
Traditional open interventions have been progressively replaced with minimally invasive techniques. Most notably, direct visual feedback is transitioned into indirect, image-based feedback, leading to the wide use of image-guided interventions (IGIs). One essential process of all IGIs is to align some 3D data with 2D images of patient through a procedure called 3D-2D registration during interventions to provide better guidance and richer information. When the 3D data is unavailable, a realistic 3D patient-speci_c model needs to be constructed from a few 2D images. The dominating methods that use only image intensity have narrow convergence range and are not robust to foreign objects presented in 2D images but not existed in 3D data. Feature-based methods partly addressed these problems, but most of them heavily rely on a set of \best" paired correspondences and requires clean image features. Moreover, the optimization procedures used in both kinds of methods are not e_cient. In this dissertation, two topics have been studied and novel algorithms proposed, namely, contour extraction from X-ray images and feature-based rigid/deformable 3D-2D registration. Inspired by biological and neuropsychological characteristics of primary visual cortex (V1), a contour detector is proposed for simultaneously extracting edges and lines in images. The synergy of V1 neurons is mimicked using phase congruency and tensor voting. Evaluations and comparisons showed that the proposed method outperformed several commonly used methods and the results are consistent with human perception. Moreover, the cumbersome \_ne-tuning" of parameter values is not always necessary in the proposed method. An extensible feature-based 3D-2D registration framework is proposed by rigorously formulating the registration as a probability density estimation problem and solving it via a generalized expectation maximization algorithm. It optimizes the transformation directly and treats correspondences as nuisance parameters. This is signi_cantly di_erent from almost all feature-based method in the literature that _rst single out a set of \best" correspondences and then estimate a transformation associated with it. This property makes the proposed algorithm not rely on paired correspondences and thus inherently robust to outliers. The framework can be adapted as a point-based method with the major advantages of 1) independency on paired correspondences, 2) accurate registration using a single image, and 3) robustness to the initialization and a large amount of outliers. Extended to a contour-based method, it di_ers from other contour-based methods mainly in that 1) it does not rely on correspondences and 2) it incorporates gradient information via a statistical model instead of a weighting function. Tuning into model-based deformable registration and surface reconstruction, our method solves the problem using the maximum penalized likelihood estimation. Unlike almost all other methods that handle the registration and deformation separately and optimized them sequentially, our method optimizes them simultaneously. The framework was evaluated in two example clinical applications and a simulation study for point-based, contour-based and surface reconstruction, respectively. Experiments showed its sub-degree and sub-millimeter registration accuracy and superiority to the state-of-the-art methods. It is expected that our algorithms, when thoroughly validated, can be used as valuable tools for image-guided interventions. / published_or_final_version / Orthopaedics and Traumatology / Doctoral / Doctor of Philosophy
23

Deconvolution of three-dimensional medical ultrasound

Gomersall, William Henry January 2011 (has links)
No description available.
24

Investigation of physical processes in digital x-ray tomosynthesis imaging of the breast

Sechopoulos, Ioannis 14 March 2007 (has links)
Early detection is one of the most important factors in the survival of patients diagnosed with breast cancer. For this reason the development of improved screening mammography methods is one of primary importance. One problem that is present in standard planar mammography, which is not solved with the introduction of digital mammography, is the possible masking of lesions by normal breast tissue because of the inherent collapse of three-dimensional anatomy into a two-dimensional image. Digital tomosynthesis imaging has the potential to avoid this effect by incorporating into the acquired image information on the vertical position of the features present in the breast. Previous studies have shown that at an approximately equivalent dose, the contrast-detail trends of several tomosynthesis methods are better than those of planar mammography. By optimizing the image acquisition parameters and the tomosynthesis reconstruction algorithm, it is believed that a tomosynthesis imaging system can be developed that provides more information on the presence of lesions while maintaining or reducing the dose to the patient. Before this imaging methodology can be translated to routine clinical use, a series of issues and concerns related to tomosynthesis imaging must be addressed. This work investigates the relevant physical processes to improve our understanding and enable the introduction of this tomographic imaging method to the realm of clinical breast imaging. The processes investigated in this work included the dosimetry involved in tomosynthesis imaging, x-ray scatter in the projection images, imaging system performance, and acquisition geometry. A comprehensive understanding of the glandular dose to the breast during tomosynthesis imaging, as well as the dose distribution to most of the radiosensitive tissues in the body from planar mammography, tomosynthesis and dedicated breast computed tomography was gained. The analysis of the behavior of x-ray scatter in tomosynthesis yielded an in-depth characterization of the variation of this effect in the projection images. Finally, the theoretical modeling of a tomosynthesis imaging system, combined with the other results of this work was used to find the geometrical parameters that maximize the quality of the tomosynthesis reconstruction.
25

Development of diffuse optical tomography for imaging the brain /

Cheng, Xuefeng. January 2000 (has links)
Thesis (Ph.D.)--Tufts University, 2000. / Adviser: David A. Boas. Submitted to the Dept. of Electrical Engineering and Computer Science. Includes bibliographical references (leaves 139-147). Access restricted to members of the Tufts University community. Also available via the World Wide Web;
26

Craniofacial fracture patterns : a thesis submitted for the degree of Doctor of Medicine /

Cooter, Rodney D. January 1990 (has links) (PDF)
Thesis (M.D.)--Dept. of Surgery, University of Adelaide, Dept. of Surgery, 1992. / Typescript (Photocopy). Includes bibliographical references (leaves 243-284).
27

Investigation of physical processes in digital x-ray tomosynthesis imaging of the breast

Sechopoulos, Ioannis. January 2007 (has links)
Thesis (Ph. D.)--Biomedical Engineering, Georgia Institute of Technology, 2007. / Andrew Karellas, John N. Oshinski, Xiaoping P. Hu, Carl J. D'Orsi and Ernest V. Garcia.
28

Three-dimensional assessment of facial morphology in infants with cleft lip and palate

Hood, Catherine Anne. January 2005 (has links)
Thesis (Ph.D.) - University of Glasgow, 2005. / Includes articles from journals: International journal of paediatric dentistry, vol. 13, 2003, pp. 404-410 ; Cleft palate-craniofacial journal, vol. 41, no. 1, 2004 ; Cleft palate-craniofacial journal vol. 40, no. 5, 2003. Ph.D. thesis submitted to the Faculty of Medicine, University of Glasgow, 2005. Includes bibliographical references. Print version also available.
29

3-D modeling and finite element analysis of the tibia

Rajani, Sailesh. January 1995 (has links)
Thesis (M.S.)--Ohio University, March, 1995. / Title from PDF t.p.
30

Automatic segmentation of brain structures for radiotherapy planning

Joshi, Pallavi V. January 2005 (has links)
Thesis (M.S. in Electrical Engineering)--Vanderbilt University, May 2005. / Title from title screen. Includes bibliographical references.

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