An Electrical Impedance Spectroscopy System for Breast Cancer Detection

This paper describes Rensselaer's ACT 4 electrical impedance tomography system which has been developed for breast cancer detection. ACT 4 acquires electrical impedance data at a set of discrete frequencies in the range from 3.33 kHz to 1 MHz and can support up to 72 electrodes. The instrument applies either voltages or currents to all the electrodes simultaneously and measures the resulting currents and/or voltages. Radiolucent electrode arrays are applied to the compression plates of an x-ray mammography system for collecting impedance data in register with x-ray images. The analog front-end electronics are supported with a distributed digital system, including a computer, Digital Signal Processors (DSPs) and Field-Programmable Gate Arrays (FPGAs). A Microsoft Visual C/C++ -based user interface controls the system operation. The overall system architecture is presented as well as performance results.