109 results about "Impedance distribution" patented technology

An electroimpedance tomograph is provided with a plurality of electrodes (1), which can be placed on the body of a patient and are connected to a control and evaluating unit (20) via a selector switch (60). The control and evaluating unit (20) cooperates with the selector switch (60) such that two electrodes each are supplied with alternating current from an AC power source (22). The detected analog voltage signals of the other electrodes are sent into the control and evaluating unit (20) via a measuring amplifier (62) and AD converter (64) and are processed there in order to reconstruct the impedance distribution of the body in the plane of the electrodes therefrom. A symmetrical AC power source (22) is used to reduce common-mode signals. To make it possible to suppress errors due to common-mode signals, provisions are made for the control and evaluating unit (20) to be set up for making available an additional common-mode signal at an output during an adjusting mode of operation and to send it to the body via common-mode signal electrodes (4, 90) that can be placed on the body. The control and evaluating unit (20) is prepared, furthermore, to adjust the measuring amplifier (62) according to value and phase for each electrode pair connected by the selector switch (60) such that the common-mode signal at the output of the measuring amplifier (62) is minimized, and the adjusted parameters are stored for each electrode pair.