"August, 2003" Bibliography: p. 261-268. In this thesis, wavelet transforms are chosen as the primary analytical tool for texture analysis. Specifically, Dual-Tree Complex Wavelet Transform is applied to the texture segmentation problem. Several possibilities for feature extraction and clustering steps are examined, new schemes being introduced and compared to known techniques.

From one treatment to the next, considerable effort is made to accurately position radiotherapy patients according to their treatment plans. However, some variation is unavoidable. The target volume and the organs at risk may also move within the patient and/or change shape during the treatment. Thus, it is important to be able to verify the success of the treatment by determining the position of patient and the dose deposited in the patient at each fraction. One possibility to achieve this, particularly when equipment, time and budgets are limited, would be to collect limited information while the patient is on the treatment couch. This research was aimed to develop a method for optimum beam position determination, for each patient-specific case. The optimized beam positions would balance the both treatment planning and image reconstruction, so that the patient???s image can be obtained during the treatment delivery using the information collected from the same angles as used for treatment. This will allow verification of the dose deposited in the patient for every fraction. Using a limited number of angles for image reconstruction, the dose to the patient can be minimized. This work has two major parts, beam position optimization for image reconstruction and beam position optimization for treatment planning. These two optimizations are then combined to obtain the optimum beam position for both image reconstruction and treatment planning. An objective function, projection correlation, was developed to investigate the image reconstruction method using limited information. Another objective function, the average optimization quality factor, was also introduced to optimize beam positions for treatment planning. Two optimization methods, the gradient descent method and the simulated annealing based on these objective functions were used to determine the beam angles. The results show that the projection correlation presents several advantages. It can be applied without any iterations, and it produces a fast algorithm. The present research will allow selection of the optimum beam positions without excessive computational cost for treatment planning and imaging. By combining the projection correlation and the average optimization quality factor together with more advanced image reconstruction software this could potentially be used in a clinical environment.

"August, 2003" / Bibliography: p. 261-268. / xxvi, 268 p. : ill. (some col.) ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / In this thesis, wavelet transforms are chosen as the primary analytical tool for texture analysis. Specifically, Dual-Tree Complex Wavelet Transform is applied to the texture segmentation problem. Several possibilities for feature extraction and clustering steps are examined, new schemes being introduced and compared to known techniques. / Thesis (Ph.D.)--University of Adelaide, Dept. of Electrical and Electronic Engineering, 2003

Thesis (Ph. D.)--University of Hong Kong, 2007. / Title proper from title frame. Also available in printed format.

Improvements have been made to the spatial coherence method for automatically determining cloud-free ocean radiances in satellite imagery by incorporating the spectral signatures of reflecting surfaces. The spatial coherence method relies on the fact that small-scale cloud-free regions typically exhibit uniform emission and uniform reflection. While small-scale overcast regions typically exhibit uniform emission, they often exhibit considerable variability in reflectance. On rare occasions the requirements of spatial uniformity are not met and errors are produced in estimated cloud-free radiances. The frequency of errors in identification of cloud-free and overcast pixels was assessed using two years of Advanced Very-High Resolution Radiometer (AVHRR) data from six regions of the globe. Significant improvement in the identification of cloud-free radiances is obtained by including a test of Q, the ratio of the AVHRR channel 2 (0.83-μm) reflectance to channel 1 (0.63-μm) reflectance. Q varies depending on whether the reflecting surface is cloud-free ocean, cloud-free land, or overcast by clouds. A study was conducted to determine the dependence of Q for overcast pixels on changes in season and geography. While some variation is evident due to satellite viewing angle and differences in atmospheric water vapor content, these effects are sufficiently small that constant thresholds may be used to help separate cloud-free and overcast pixels. The modified spatial coherence method uses the threshold for Q and radiance uniformity thresholds at 0.63-μm and 11-μm to identify cloud-free and overcast pixels. A sensitivity study was performed to determine the dependence of cloud-free ocean radiance estimates on the values of the uniformity thresholds. The results of the study indicate that using thresholds of 0.5% for the 0.63-μm reflectivity and 0.5 mWm⁻²sr⁻¹cm for the 11-μm radiance, produces cloud-free radiances that are rarely biased by more than 0.4% for reflectances at 0.63 μm and 0.4 K for the 11-μm brightness temperature. The uniformity and Q thresholds may be used for a large variety of scenes from different seasons and geographic areas. / Graduation date: 2000

Thesis (Ph.D)--Stanford University, 1999. / Title from pdf t.p. (viewed April 3, 2002). "January 1999." "Adminitrivia V1/Prg/20000907"--Metadata.

Thesis (Ph.D.)--University of Delaware, 2006. / Principal faculty advisor: Fouad Kiamilev, Dept. of Electrical and Computer Engineering. Includes bibliographical references.

Thesis (M.S.)--Brigham Young University. Dept. of Electrical and Computer Engineering, 2005. / Includes bibliographical references (p. 153-156).

Thesis (M.S.)--Rochester Institute of Technology, 2007. / Typescript. Includes bibliographical references (leaves 63-64).

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