Full-wave computed tomography. Part 4: Low-frequency electric current CT

Imaging of 2-dimenslonal distributions of electric conductivity, from voltages measured on perlpheries of the distributions, is studied. It is understood that low-frequency electric currents are injected into the distributions. Optimum placement of electrodes, for maximising the value and sensitivity of voltage measurements, is studied theoretically and experimentally. The imaging theory developed suggests that arbitrary conductivity distributions cannot be unambiguosly reconstructed. Pieccwisc-constant distributions can be imaged successfully, however. Specimen images reconstructed from laboratory measurements, are presented of circularly symmetric conductivity distributions and of piecewise-constant disuibutions.