| 摘要 |
An electric impedance tomography device with chest electrodes, a display and a control and analyzing unit to determine a time series of a global ventilation curve from the sequence of reconstructed matrices as a time series of the mean impedance change or of a measured respiration volume, to divide an inspiration or expiration phase into a number of steps of equal volume change, to determine the times corresponding to these steps, to determine the change in local impedance between these times for each image element, the ratio of this local change in impedance to the global equal volume change to form a local sequence of relative impedance changes of the image element as a function of the steps of equal volume change, to determine a scalar indicator characteristic as a function of the steps of equal volume change and to display each image element based on the respective scalar indicator. |
| 主权项 |
1. An electric impedance tomography device comprising:
a plurality of electrodes, which can be arranged about the chest of a patient; a display device; and a control and analyzing unit, which is configured to supply an electrode pair as a feeding electrode pair with an alternating current or with an alternating voltage, to record a voltage signal or current signal as a measured signal with a plurality of the remaining electrode pairs from the plurality of electrodes, and to let other electrode pairs of the plurality of electrode pairs act consecutively as the feeding electrode pair, to reconstruct from the measured signals, with a reconstruction algorithm, a matrix of image elements, which represent the distribution of the impedance changes in the electrode plane, and to repeatedly record measured signals over time and to reconstruct matrices, wherein the control and analyzing unit determines a time series of a global ventilation curve from the sequence of the reconstructed matrices as a time series of the mean impedance change or as a time series of a measured respiration volume and determines an inspiration or expiration phase of the global ventilation curve, divides the inspiration or expiration phase of the global ventilation curve into a number of steps of equal volume change, determines times corresponding to these steps of equal volume change in the inspiration or expiration phase, determines the change in the local impedance between these times for each image element, and determines each time the ratio of this local change in impedance of the image element to the global equal volume change to form a local sequence of relative impedance changes of the image element as a function of the number of steps of equal volume change, determines, for each local sequence, a scalar indicator characteristic of the curve thereof as a function of the steps of equal volume change and displays each image element on the display device in a manner depending on the particular scalar indicator. |
