Resolution performance of an electrical impedance tomograph

The resolution of an electrical impedance tomograph (EIT) based on the equipotentials backprojection reconstruction algorithm is investigated experimentally. The tomography uses a computer-based multichannel impedance data acquisition system, the design of which is briefly described. Background noise and spatial resolution are evaluated by experiments with a saline-filled cylindrical tank similar in size to an adult human torso. The measured average noise level of 300 μS/m is equivalent to the perturbation produced by a nonconducting sphere of 2-cc volume. A spatial impulse response experiment shows that the low-frequency response of the EIT system reflects the spectral properties of a parallel ray tomograph having a detector aperture equal to the circumferential spacing of the recording electrodes