A comparison of two phase measurement techniques for magnetic impedance tomography

Abstract

Magnetic induction tomography (MIT) allows the reconstruction of conductivity distributions inside a given volume for a wide variety of industrial and medical applications. Philips is interested in using the MIT technique for acquiring information of conductivity distribution and conductivity changes in human tissue. The advantage of this technique is the contactless and non-invasive way of collecting information on the tissue. An MIT system consists of excitation coils that produce a primary magnetic field that causes eddy currents in a conductive object. The eddy current produces a secondary magnetic field that can be detected by an array of receiving coils. Improved Philips MIT setups based on IF down-conversion and high-speed sampling are compared. MIT demands an accurate measure of phase and the new setups are found to offer improvements in noise, linearity and drift over our previous system. © 2009 Springer-Verlag.