SEARCHLIGHT CT: A NEW REGULARIZED RECONSTRUCTION METHOD FOR HIGHLY COLLIMATED X-RAY TOMOGRAPHY

This thesis introduces a new method for image reconstruction in collimated Computed Tomography called Searchlight CT. The method significantly reduces the overall radiation exposure when primarily the reconstruction of a specified region of interest is required. To achieve this, the Searchlight CT approach restricts the acquisition essentially to the region of interest, yet the algorithm provides a stable and robust reconstruction of the region of interest. The algorithm uses an iteration of the X-ray Transform and its regularized inverse. The performance of the algorithm is illustrated on simulated phantoms as well as experimental data. It is tested initially on 2D data and studied in detail for the 3D case including the adaptation to spiral tomography. Various methods of regularization are explored with special a emphasis on wavelet-based non-linear regularization. Finally the sensitivity of the algorithm to noise is studied. Numerical results for all cases are provided. The outline of an analytical proof for the convergence conditions is provided. The convergence is validated by the computation of the spectral radius of the iteration operator in various cases. A detailed analysis of the eigenvalues and eigenvectors leads to an apriori condition on convergence.

Name thesis:degree_name

Doctor of Philosophy

Level thesis:degree_level

Doctoral

Discipline thesis:degree_discipline

Mathematics

Grantor

University of Houston

Year dc:date.issued

2012

Author dc:creator

• Sen, Anando 1985-

Advisor dc:contributor.advisor

• Azencott, Robert

Committee members dc:contributor.committeemember

• Labate, Demetrio
• Bodmann, Bernhard G.
• Zhou, Xiaobo

• X-ray transform
• Inverse problems
• Radon transform
• Wavelets
• Regularization
• Iterative algorithm

Statement dc:rights

• The author of this work is the copyright owner. UH Libraries and the Texas Digital Library have their permission to store and provide access to this work. Further transmission, reproduction, or presentation of this work is prohibited except with permission of the author(s).

Language dc:language.iso

eng

Handle dc:identifier.uri

http://hdl.handle.net/10657/906

OAI identifier oai:identifier

oai:uh-ir.tdl.org:10657/906