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Title: An experimental investigation to assess the feasibility of imaging medical radioisotopes with the ProSPECTus Compton Camera
Author: Patel, Amina
ISNI:       0000 0004 6059 5691
Awarding Body: University of Liverpool
Current Institution: University of Liverpool
Date of Award: 2016
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An experimental investigation into the feasibility of imaging multiple medical radioisotopes with the ProSPECTus Compton camera is presented. The aim of the project is to develop a Compton imaging system configured with segmented solid state detectors, for the purpose of alleviating the limitations of conventional Single Photon Emission Computed Tomography (SPECT) systems. The ProSPECTus system consists of a Si(Li) and HPGe planar detector housed in a magnetic field compatible custom made cryostat. The investigation presented in this thesis has been undertaken with a prototype ProSPECTus system, which consists of Si(Li) and HPGe planar detectors housed in separate cryostats. Analysis of the results attained from investigations into the optimum coincidence window, noise thresholds and image reconstruction techniques as part of this thesis are to be used to inform future developments and measurements. The work presented focuses on an investigation of simultaneous data acquisition with the medical radioisotopes 99mTc and 123I, which emit gammarays with energies of 141 keV and 159 keV, respectively. The experimental methodology of defining parameters for timing and noise thresholds is described along with system performance in terms of image quality and efficiency. A custom designed phantom is used to build source complexity and to provide qualitative and quantitative assessment of the imaging capabilities of ProSPECTus using analytical and iterative reconstruction algorithms. It has been determined that a spatial resolution of 3 mm is achievable, using iterative reconstruction of data acquired from a 139Ce point source of energy 166 keV. Quantitative analysis has revealed that an Edge Response is a good measure of determining the resolvability of extended source distributions. It has been proved that the spectroscopic response enables ProSPECTus to image 99mTc and 123I simultaneously. This would otherwise require complex peak deconvolution techniques in clinical SPECT systems. An improvement in efficiency of up to a factor of 2.5 over conventional SPECT systems is demonstrated, with suggestions for further improvements, indicating a factor of 23 is achievable with the next generation system. This would potentially reduce patient dose or increase patient throughput. Suggestions are presented for the iterative reconstruction algorithm to facilitate enhanced imaging with the next generation ProSPECTus system.
Supervisor: Harkness-Brennan, L. ; Boston, H. C. Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral