| Evaluating Deformation Corrections in Electrical Impedance Tomography (2008) | |||||||||||
Abstract | |||||||||||
| Electrical Impedance Tomography (EIT) uses the difference in measurements between surface electrodes to reconstruct an image of the conductivity of the contained medium. However, changes in measurements result from changes in internal conductivity and changes in the shape of the medium relative to the electrode positions. Failure to account for shape changes results in a conductivity image with significant artifacts. Previous work to address shape changes in EIT has shown that: a) theoretically, for an infinite number of electrodes, non-conformal changes in boundary shapes and electrode locations can be uniquely determined (Lionheart, 1998); and b) in some cases, conductivity and shape changes can be recovered using a combined image reconstruction model of both conductivity and shape changes (Soleimani et al, 2006). This work has shown that the shape change problem can be partially addressed. In this paper, we explore the limits of compensation for boundary movement in EIT, using three approaches: first, a theoretical model is developed to separate a deformation vector field into conformal and non-conformal components, from which the reconstruction limits may be determined; next, finite element models are constructed from which EIT measurements are simulated; finally, an experimental phantom is constructed using a deformable gasket and stainless steel electrodes in a saline medium, from which boundary deformation measurements are acquired. | |||||||||||
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