Electrical Impedance Tomography and Spectroscopy
Abstract:
Electrical impedance tomography systems apply patterns of currents and measure the resulting patterns of voltages on electrode arrays on part of a bodies surface. From these approximate measures of the Dirichlet to Neumann maps for Maxwell's equations, the systems reconstruct and display approximations to the electrical conductivity and permittivity inside this body. Since blood has a higher conductivity than most tissues as well as air, these images can be used to determine the flow of blood between a patients heart and lungs in real time. When the measurements are made at many frequencies the electrical impedance spectra (EIS) or dispersion relations can also be imaged. Since the EIS for breast cancer is different in shape from that of benign tissue, EIS images can be used to diagnose breast cancer. We explain how these images are made by our ACT4 system. We will show pictures and movies to illustrate how the ACT systems are used to image heart and lung function as well as to diagnose breast cancer. If time permits we will explain how these inverse problems for Maxwell's equations can be solved by direct - non iterative- methods using complex geometrical optics and d-bar equations.
MCIAM Seminar