Speaker:  David Isaacson, RPI

Title: Problems in Electrical Impedance Tomography


Abstract:

Electrical Impedance Tomography (EIT) systems typically apply currents   
and measure voltages on arrays of electrodes covering a portion of the 
surface of a body. Approximate reconstructions and displays of the 
electrical conductivity and permittivity distributions inside the body 
are made from these surface measurements. Since lungs filled with air 
have higher conductivity than lungs depleted of air, impedance images
of the lungs can be used to monitor a patients lung function. Similarly
hearts filled with blood have a higher conductivity than when depleted 
of blood, so that impedance images can be used to monitor a patient's 
cardiac function. Many breast tumors have a higher conductivity than 
surrounding normal tissue so that impedance images may be used to help 
improve the diagnosis of breast cancer.


We will explain how the problem of forming impedance images leads 
to inverse boundary value problems for Maxwell's equations. We 
will describe the adaptive current tomography systems (ACT) built 
at RPI. Images and movies made by these ACT systems showing heart and 
lung function will be presented. Electrical Impedance spectroscopy 
(EIS) will be explained. Applications of EIS to breast cancer diagnosis 
will be presented.