Time-domain electrical impedance tomography by numerical analysis of the step response

Abstract

This work describes the theoretical basis of an electrical impedance tomography imaging system based on numerical analysis of the step response. Its novelty relies on the use of time domain for rendering the tomographic images. Following the injection of a Heaviside-step current through two electrodes, the voltage-response is measured on all couple of electrodes according to the neighbouring strategy; this process is repeated on every pair of consecutive electrodes. Based on the measurements, a tomographic image is reconstructed using the Gauss-Newton-Raphson algorithm. We tested the technique by simulating two representative circuits: one symmetrical pseudo-isotropic and one pseudo-anisotropic in AC, while both pseudo-isotropic at DC. The time-domain reconstructed images show the second network's pseudo-anisotropy while allowing the system to show its tendency to pseudo-isotropy when the time elapses towards DC-steady-state. This novel technique for reconstructing electrical impedance tomographic images may shed new light on sensing slight differences in tissues while being fast and low-cost.