Thesis (Ph. D.)--University of Hong Kong, 2006. / Title proper from title frame. Also available in printed format.

Thesis (Ph. D.)--University of Hong Kong, 2006. / Title proper from title frame. Also available in printed format.

This paper presents the theory behind a model for a two-stage analog network for edge detection and image reconstruction to be implemented in VLSI. Edges are detected in the first stage using the multi-scale veto rule, which eliminates candidates that do not pass a threshold test at each of a set of different spatial scales. The image is reconstructed in the second stage from the brightness values adjacent to edge locations. The MSV rule allows good localization and efficient noise removal. Since the reconstructed images are visually similar to the originals, the possibility exists of achieving significant bandwidth compression.

Computed tomography imaging spectrometer (CTIS) technology is introduced and its use is discussed. An iterative method is presented for CTIS image-reconstruction in the presence of both photon noise in the image and post-detection Gaussian system noise. The new algorithm assumes the transfer matrix of the system has a particular structure. Error analysis, performance evaluation, and parallelization of the algorithm is done. Complexity analysis is performed for the proof of concept code developed. Future work is discussed relating to potential improvements to the algorithm. An intuitive explanation for the success of the new algorithm is that it reformulates the image reconstruction problem as a constrained problem such that an explicit closed form solution can be computed when the constraint is ignored. Incorporating the constraint leads to an inverse matrix problem which can be dealt with using a conjugate gradient method. A weighted iterative refinement technique is employed because the conjugate gradient solver is terminated prematurely. This dissertation makes the following contributions to the state of the art. First, our method is several orders of magnitude faster that the previous industry best (multiplicative algebraic reconstruction technique (MART) and mixed-expectation reconstruction technique (MERT)). Second, error bounds are established. Third, open source proof of concept code is made available.

Thesis (Ph. D.)--University of Hong Kong, 2006. / Title proper from title frame. Also available in printed format.

This research is to study the fundamental theory of Synthetic Aperture Sonar (SAS) through numerical simulation and experimental analysis. The basic principle of SAS is to enhance the capability of spatial resolution by moving the transducer element to increase aperture so that it achieves a better resolution. The factors affecting the capability of resolution include the actual size of the transducers, frequency and its bandwidth, pulse length, and moving speeds. The effects of various factors on the resolution were examined through numerical simulation. The results have shown that the smaller the true size of the transducer, the better the resolution. Moreover, when the bandwidth is increased, the resolution also increases. The SAS is sensitive to the speed of movement due to the fact that data acquisition may be limited, therefore the speed can not be too high, e.g., less than 1.5 m/s. The experiment was carried out in a water tank of size 4 m x 3.5 m x 2 m. The transducers of AST MK VI 192 kHz were employed to transmit and receive signals. Copper spheres of various sizes (3 cm, 6 cm, 8 cm diameter) were used as targets. The data were obtained and analyzed, and the results have shown that the resolution may be achieved by SAS analysis, establishing the fundamental principle and offering opportunity for future study.

Fluorescence enhanced optical tomography is a promising molecular imaging modality which employs a near infrared fluorescent molecule as an imaging agent and time-dependent measurements of fluorescent light propagation and generation. In this dissertation a novel fluorescence tomography algorithm is proposed to reconstruct images of targets contrasted by fluorescence within the tissues from boundary fluorescence emission measurements. An adaptive finite element based reconstruction algorithm for high resolution, fluorescence tomography was developed and validated with non-contact, planewave frequency-domain fluorescence measurements on a tissue phantom. The image reconstruction problem was posed as an optimization problem in which the fluorescence optical property map which minimized the difference between the experimentally observed boundary fluorescence and that predicted from the diffusion model was sought. A regularized Gauss-Newton algorithm was derived and dual adaptive meshes were employed for solution of coupled photon diffusion equations and for updating the fluorescence optical property map in the tissue phantom. The algorithm was developed in a continuous function space setting in a mesh independent manner. This allowed the meshes to adapt during the tomography process to yield high resolution images of fluorescent targets and to accurately simulate the light propagation in tissue phantoms from area-illumination. Frequency-domain fluorescence data collected at the illumination surface was used for reconstructing the fluorescence yield distribution in a 512 cm3, tissue phantom filled with 1% Liposyn solution. Fluorescent targets containing 1 micro-molar Indocyanine Green solution in 1% Liposyn and were suspended at the depths of up to 2cm from the illumination surface. Fluorescence measurements at the illumination surface were acquired by a gain-modulated image intensified CCD camera system outfitted with holographic band rejection and optical band pass filters. Excitation light at the phantom surface source was quantified by utilizing cross polarizers. Rayleigh resolution studies to determine the minimum detectable sepatation of two embedded fluorescent targets was attempted and in the absence of measurement noise, resolution down to the transport limit of 1mm was attained. The results of this work demonstrate the feasibility of high-resolution, molecular tomography in clinic with rapid non-contact area measurements.

Thesis (Ph. D.)--Oregon State University, 2010. / Printout. Includes bibliographical references (leaves 115-117). Also available on the World Wide Web.

Thesis (Ph. D.)--University of Washington, 2003. / Vita. Includes bibliographical references (leaves 113-124).

Includes bibliographical references (p. 114-123).