Early breast cancer detection utilizing clustered electrode arrays in impedance imaging.

摘要

Electrical Impedance Tomography (EIT) is a non-invasive technique used to image the electrical conductivity and permittivity distributions within a body from electrical measurements taken on the body's boundary. Electrical currents are applied to electrodes placed on a patient's body and the voltages necessary to maintain the currents are measured. The voltage and current data are used in algorithms that reconstruct and display the approximations of the internal conductivity and permittivity distributions.; The majority of present EIT techniques use circular electrode arrays. For regions of interest that make up a relatively small percentage of the imaged area, such as tumorous breast tissue, clustered electrode arrays may be a more practical configuration. The third generation adaptive current tomography system, ACT3, at Rensselaer Polytechnic Institute has only been used with circular arrays. It is the purpose of this thesis to determine which clustered electrode array configuration and what current patterns best distinguish a given inhomogeneity from a background conductivity in a rectangular tank of saline solution.; We considered a single rectangular array of electrodes and two rectangular arrays of electrodes placed on opposite sides of the tank and study how these configurations and various current patterns affect the distinguishability of small and large conducting and insulating targets placed at several different depths and positions in the tank. The study was motivated in part by preliminary results from a commercial system which tries to detect tumorous breast tissue using clustered electrode arrays. We have attempted to duplicate the current patterns used by the commercial system and have compared them to other current patterns which are demonstrated to yield higher distinguishability. Therefore, the detection of breast tumors with ACT3 is promising.; Inhomogeneities can also be located with good resolution in addition to simply being detected. The general area of a target is observable and this regional resolution decreases as the target depth below the surface of the array increases. With the mobility of the clustered electrode arrays, several placements of the electrodes over a suspicious area may improve the location of a lesion in all three dimensions.