A sensitivity coefficient method for the reconstruction of electrical impedance tomograms.

A number of proposed reconstruction algorithms for electrical impedance tomography have employed the concept of a sensitivity coefficient which can be used to relate the magnitude of a voltage change measured at the surface of an object to the change in impedance within the object which has given rise to it. Iterative algorithms are required where the approach to the full non-linear problem involves the formal inversion of the sensitivity coefficient matrix, but the task of matrix inversion is still not trivial even for a linearised version of the problem. An alternative approach is to use sensitivity coefficients calculated from Laplace fields for single-pass image reconstruction in a manner more closely related to back-projection methods. A reconstruction algorithm employing sensitivity coefficients in this manner is described and images of a phantom and a human chest section produced using the algorithm are displayed.