Patent ID: 7288943

Claim:
An electroimpedance tomograph comprising: a plurality of electrodes for placement on a body of a patient; a control and evaluating unit; a selector switch; a measuring amplifier; an AD converter; a symmetrical AC power source, said electrodes being connected to said control and evaluating unit via said selector switch, wherein said control and evaluating unit cooperates with said selector switch such that two of said electrodes as an electrode pair are each supplied with an alternating current from said AC power source and the detected analog voltage signals of the other said electrodes are sent into said control and evaluating unit via said measuring amplifier and said AD converter and are processed there in order to reconstruct therefrom an impedance distribution of the body in the plane of said electrodes; and common-mode signal electrodes for placement on the body of a patient, said symmetrical AC power source being used to reduce common-mode signals, said control and evaluating unit being set up to make available an additional common-mode signal at an output during an adjusting mode of operation and to send said additional common-mode signal to the body via said common-mode signal electrodes, and said control and evaluating unit furthermore being set up to adjust said measuring amplifier according to value and phase for each electrode pair connected by said selector switch such that the common-mode signal at the output of said measuring amplifier is minimized, and the adjusted parameters are stored for each electrode pair, wherein said control and evaluating unit is set up, furthermore, to poll the corresponding adjusted parameters during the measuring mode for each connected electrode pair and to adjust said measuring amplifier according to said adjusted parameters.