Embebed Wavelet Image Reconstruction in Parallel Computation Hardware

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Abstract

The University of Manchester, September 2015. Abstract of thesis submitted by Jorge Guevara Escobedo for the Degree of Doctor of Philosophy (PhD) entitled “Embedded wavelet image reconstruction in parallel computation hardware”.In this thesis an algorithm is demonstrated for the reconstruction of hard- field Tomography images through localized block areas, obtained in parallel and from a multiresolution framework. Block areas are subsequently tiled to put together the full size image. Given its properties to preserve its compact support after being ramp filtered, the wavelet transform has received to date much attention as a promising solution in radiation dose reduction in medical imaging, through the reconstruction of essentially localised regions. In this work, this characteristic is exploited with the aim of reducing the time and complexity of the standard reconstruction algorithm. Independently reconstructing block images with geometry allowing to cover completely the reconstructed frame as a single output image, allows the individual blocks to be reconstructed in parallel, and to experience its performance in a multiprocessor hardware reconfigurable system (i.e. FPGA). Projection data from simulated Radon Transform (RT) was obtained at 180 evenly spaced angles. In order to define every relevant block area within the sinogram, forward RT was performed over template phantoms representing block frames. Reconstruction was then performed in a domain beyond the block frame limits, to allow calibration overlaps when fitting of adjacent block images. The 256 by 256 Shepp-Logan phantom was used to test the methodology of both parallel multiresolution and parallel block reconstruction generalisations. It is shown that the reconstruction time of a single block image in a 3-scale multiresolution framework, compared to the standard methodology, performs around 48 times faster. By assuming a parallel implementation, it can implied that the reconstruction time of a single tile, should be very close related to the reconstruction time of the full size and resolution image.

Keyword(s)

Wavelets, Multiresolution Tomography, Fast Tomography Reconstruction, Radon Transform, Filtered Backprojection, Computed Tomography, Local Tomography, Parallel Tomography Reconstruction, Embedded Tomography, Reconfigurable Hardware, FPGAs

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