Layered Model for Breasts in Electrical Impedance Tomography

We are presently using Electrical Impedance Tomography as a technique for breast cancer imaging, determining the admittivity distribution inside the breast. The admittivities we observed in compressed breasts in EIT were lower than those seen in earlier studies involving whole chest imaging. We attribute this to a thin low admittance skin layer which dominates in compressed breasts. To more accurately model breasts, we have developed a layered analytical forward model. Our layered model has three layers, thin low admittivity top and bottom layers representing skin and a thicker high admittivity middle layer representing breast tissue. In this paper we derive the forward solution for this layered geometry and compare it to the forward solution for the homogeneous case. We also demonstrate the improvement in reconstruction of a target embedded in a layered body when the homogeneous forward solution is replaced by the layered forward solution.