Data collection for electrical impedance tomography
The invention refers to a method for carrying out data collection on electrodes placed on a body for subsequent processing of an electrical impedance tomography image of a corresponding part of said body. In order to improve the resolution of electrical impedance tomography systems without noticeably affecting the signal-to-noise ratio, the method according to the invention comprises the steps of placing the electrodes on a peripheral line around the body, applying a current pattern from a current source to at least one pair of electrodes, and measuring differential potentials between pairs of electrodes, wherein at least one intermediate electrode lies in between each pair of electrodes for measuring the differential potentials and the differential potentials of one current pattern for the subsequent image processing refer to at least three different pairs of electrodes with no electrode used more than twice for each current pattern.
1. Method for carrying out data collection on electrodes placed on a body for subsequent processing of an electrical impedance tomography image of a corresponding part of the body by means of a reconstruction algorithm, the method comprising the steps of:
placing the electrodes on a peripheral line around the body;
applying a current pattern from a current source to at least one pair of electrodes;
measuring differential potentials between pairs of electrodes;
selecting the pairs of electrodes so that at least one intermediate electrode lies in between each pair of electrodes for measuring the differential potentials;
selecting the pairs of electrodes so that the at least one intermediate electrode is part of another pair of electrodes for measuring the differential potentials;
using the differential potentials of one current pattern for the subsequent image processing from at least three different pairs of electrodes with no electrode used more than twice for each current pattern; and
accounting for spatial overlap information in the data collection by the reconstruction algorithm.
2. Method according to claim 1 , wherein the same number of electrodes lies in between each pair of electrodes for measuring a differential potential.
3. Method according to claim 1 , wherein the same number of electrodes lies in between each pair of electrodes for applying a current.
4. Method according to claim 1 , wherein for one current pattern each electrode on said peripheral line is used either for applying a current or for measuring differential potentials.
5. Method according to claim 1 , wherein for one current pattern each electrode on said peripheral line is used for measuring differential potentials.
6. Method according to claim 5 , wherein for one current pattern each electrode is used twice for measuring differential potentials.
7. Method according to claim 1 , wherein a differential potential measurement is performed by measuring a first voltage of a first electrode with regard to the ground of the current source, measuring a second voltage of a second electrode with regard to the ground of the current source and subtracting the second voltage from the first voltage.
8. Method according to claim 1 , wherein a balanced current source is used having a mid-point earthing as ground.
9. Method according to claim 1 , wherein the electrodes are placed on at least one electrode unit.
10. Apparatus for carrying out data collection for an electrical impedance tomography image, comprising:
electrodes placed on a peripheral line around a body for processing of said electrical impedance tomography image of a corresponding part of the body by means of a reconstruction algorithm;
current source for applying a current pattern to at least one pair of electrodes;
measuring means for measuring differential potentials between pairs of electrodes using electrodes for the pairs of electrodes such that at least one intermediate electrode lies in between each pair of electrodes for measuring the differential potentials and the at least one intermediate electrode is part of another pair of electrodes for measuring the differential potentials, wherein the differential potentials of one current pattern for the subsequent image processing refer to at least three different pairs of electrodes and the measuring means uses no electrode more than twice for each current pattern; and
computer means for implementing the reconstruction algorithm accounting for spatial overlap information in the data collection.
11. Apparatus according to claim 10 , wherein the same number of electrodes lies in between each pair of electrodes for measuring a differential potential.
12. Apparatus according to one of the claim 10 , wherein the same number of electrodes lies in between each pair of electrodes for applying a current.
13. Apparatus according to one of the claim 10 , wherein for one current pattern each electrode on said peripheral line is used either for applying a current or for measuring differential potentials.
14. Apparatus according to one of the claim 10 , wherein for one current pattern each electrode on said peripheral line is used for measuring differential potentials.
15. Apparatus according to claim 14 , wherein for one current pattern each electrode is used twice for measuring differential potentials.
16. Apparatus according to one of the claim 10 , wherein a differential potential measurement is performed by measuring a first voltage of a first electrode with regard to the ground of the current source, measuring a second voltage of a second electrode with regard to the ground of the current source and subtracting the second voltage from the first voltage.
17. Apparatus according to one of the claim 10 , wherein a balanced current source is used having a mid-point earthing as ground.
18. Apparatus according to one of the claim 10 , wherein the electrodes are placed on at least one electrode unit.