Development of a new reconstruction algorithm and an electrical impedance tomography system

Electrical Impedance Tomography (EIT) is a potentially useful imaging modality. The images obtained from EIT are based on the resistivities of the body being studied. We have reviewed some impedance imaging techniques and have presented results of our own research in this dissertation. My contribution to the research in EIT includes the development of a new reconstruction algorithm, the testing and characterization of the hardware and software systems with a saline tank, and the study of applying our EIT to temperature monitoring in hyperthermia treatment. The first prototype system at the University of Washington was developed in 1985. I modified the system and developed the second prototype system. After implementing three reconstruction algorithms developed by other researchers (Kim and Webster, 1985; Brown et al., 1985; Lewitt, 1983), I compared, analyzed, and verified the results of the algorithms from simulation runs and from physical data collected by the new hardware system.; The EIT system we developed is capable of collecting data from an array of electrodes (up to 64) and reconstructing resistivity images. Our hardware system is flexible in that the functions of each electrode can be programmed individually so that a variety of electrode configurations can be tested for optimal image reconstructions. Several impedance image reconstruction algorithms using the finite element method are discussed in this dissertation. Suggestions are also given in modifying some of the algorithms. Both the hardware and software were subject to many tests to verify their functions and performances. The system is able to resolve resistivity change areas embedded in a given resistivity background. The development of the imaging techniques is still in its early stage. Difficulties and limitations of the hardware system are examined, and development of the field in the future in discussed.