The backprojection method for electrical impedance image reconstruction has been adapted for the opposing current drive configuration implemented in the second generation of Aberdeen impedance imaging systems. The logarithmic conformal transformation is used to solve the Forward problem for a two-dimensional homogeneous medium of circular cross-section. Pixel weights of backprojection are calculated from the normalised distances of the pixel centres from the boundary side of backprojection. An experimental solution to the Forward problem is a homogeneous medium of irregular cross-section and three-dimensional boundary is proposed and implemented. A thorax phantom was built for this purpose using radiotherapy moulding techniques. The potential distribution in this phantom was measured using a tetrapolar inpedance measuring device and the equipotential lines falling on the electrodes were plotted. A reconstruction matrix capable of reconstructing dynamic impedance images of the thorax was formulated. Images representing resistivity change distributions between maximum inspiration and maximum expiration have been reconstructed. These thorax cross-section images show the most faithful representation of the expected resistivity changes due to respiration.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:357940 |
| Date | January 1993 |
| Creators | Kalisse, Camille George Emile |
| Publisher | University of Aberdeen |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Source | http://digitool.abdn.ac.uk/R?func=search-advanced-go&find_code1=WSN&request1=AAIU055336 |
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