Localization of objects within a conductive volume

Patent metadata

Field	Value
Publication number	US-11666242-B2
Application number	US-202016787828-A
Country	US
Kind code	B2
Filing date	Feb 11, 2020
Priority date	Sep 26, 2014
Publication date	Jun 6, 2023
Grant date	Jun 6, 2023

Abstract

An example method includes applying a localization signal to a source electrode positioned within a conductive volume and a ground electrode at a known location. Electrical activity is sensed at a plurality of sensor electrodes distributed across an outer surface of the conductive volume. The locations of each of the sensor electrodes and the location of the ground electrode being stored in memory as part of geometry data. The electrical activity sensed at each of the sensor electrodes is stored in the memory as electrical measurement data. The method also includes computing a location of the source electrode by minimizing a difference between respective pairs of source voltages determined for the plurality of sensor electrodes. The source voltage for each of the sensor electrodes is determined based on the electrical measurement data and the geometry data.

First claim

What is claimed is:

1. A system comprising:
a plurality of sensors configured to sense electrical activity at locations distributed across a conductive volume, locations of each of the plurality of sensors being predetermined with respect to a spatial coordinate system and stored in memory as geometry data;
a source electrode positioned within the conductive volume at an unknown location that is to be determined;
a signal generator to supply electrical energy to the source electrode, the electrical energy corresponding to a generated source voltage, which generates an electric field, there being a circuit path extending from the source electrode to an electrical ground at a position on an outer surface of the conductive volume, the electrical ground being coupled to the signal generator; and
a location calculator implemented as instructions executable by a computer processor in the system, the location calculator configured to compute the location of the source electrode by minimizing a difference between respective pairs of determined source voltages for a plurality of possible locations of the source electrode, wherein the determined source voltages are determined for the plurality of sensors, and each of the determined source voltages is determined for a respective one of the plurality of sensors based on a respective sensor measurement of voltage in response to the electric field and based on relative locations of the sensors determined from the geometry data.

2. The system of claim 1 , wherein the location calculator is configured to compute the location of the source electrode based on the sensor measurements acquired concurrently for each of the plurality of sensors in response to the electric field.

3. The system of claim 2 , wherein the plurality of sensors includes at least three electrodes distributed across the conductive volume.

4. The system of claim 1 , wherein the geometry data specifying the predetermined location of each of the plurality of sensors comprises information generated by at least one of:
self-discovery, wherein the spatial distribution of the sensors with respect to each other or a neutral point is computed based on a programmed sequence of current or voltage applied among the sensors,
based on imaging data, or
a digitizer.

5. The system of claim 1 , further comprising a channel integrity detector implemented as instructions executable by a computer processor in the system, the channel integrity detector configured to identify one or more channels for exclusion from subsequent analysis based on one or more of correlation of a channel's signal with respect to signals of spatially neighboring channels, amplitude of the channel's signal, the channel being a short circuit or an open circuit, the geometry data and the sensor measurements for each channel identified for exclusion being made unavailable for the computation by the location calculator.

6. The system of claim 1 , further comprising volume impedance data stored in the memory to characterize impedance of the conductive volume, the location calculator configured to account for variations in the impedance of the conductive volume based on the volume impedance data.

7. The system of claim 6 , further comprising an impedance calculator implemented as instructions executable by a computer processor in the system, the impedance calculator configured to generate the volume impedance data based on electric fields sensed by the plurality of sensors in response to the electric field applied to the conductive volume.

8. The system of claim 1 , further comprising a calibration engine implemented as instructions executable by a computer processor in the system, the calibration engine configured to group the plurality of sensors into multiple subsets of the plurality of sensors by assigning each sensor to one of the subsets, the location calculator configured to compute the location of the source electrode by minimizing the difference between source voltages determined for respective sensor pairs in at least one of the subsets of the plurality of sensors.

9. The system of claim 8 , wherein the location calculator is configured to compute the location of the source electrode by aggregating source location values separately computed from corresponding sensor measurements acquired from at least two of the subsets of the plurality of sensors.

10. The system of claim 8 , wherein the calibration engine is configured to automatically determine the assignment of the plurality of sensors to the multiple subsets of the plurality of sensors based on at least one of the volume impedance data, the geometry data or imaging data.

11. The system of claim 8 , wherein the calibration engine is configured to determine the assignment of the plurality of sensors to the multiple subsets of the plurality of sensors in response to a user input selecting which sensors to include in each of the respective subsets of the plurality of sensors.

12. The system of claim 1 , wherein the location calculator further comprises a sensor selector implemented as instructions executable by a computer processor in the system, the sensor selector configured to select at least three different pairs of sensors from the plurality of sensors, the location calculator configured to compute the position based on the sensor measurements from the selected pairs of sensors.

13. The system of claim 12 , further comprising a channel integrity detector to identify for exclusion from subsequent analysis channels based on one or more of correlation of a channel's signal with respect to signals of spatially neighboring channels, amplitude of the channel's signal, the channel being a short circuit or an open circuit, to provide a remaining available subset of the plurality of sensors from which the sensor selector selects each of the selected pairs of sensors.

14. The system of claim 12 , wherein the location calculator further comprises a homogeneity calculator implemented as instructions executable by a computer processor in the system, the homogeneity calculator configured to determine an indication of homogeneity of the conductive volume between respective pairs of sensors, the sensor selector selecting each of the selected pairs of sensors into a respective subset of sensors based on the indication of homogeneity.

15. The system of claim 14 , further comprising an impedance calculator implemented as instructions executable by a computer processor in the system, the impedance calculator configured to determine impedance data representing impedance through the conductive volume, the homogeneity calculator determining the indication of homogeneity of the conductive volume based on the impedance data.

16. A method comprising:
applying a localization signal to a source electrode positioned within a conductive volume and a ground electrode at a known location with respect to the conductive volume, the known location of the ground electrode being stored in memory as part of geometry data;
sensing electrical activity at a plurality of sensor electrodes distributed across the conductive volume, a location of each of the plurality of sensor electrodes being predetermined with respect to a spatial coordinate system and stored in the memory as part of the geometry data, the electrical activity sensed at each of the plurality of sensor electrodes in response to the applied localization signal being stored in the memory as electrical measurement data; and
computing the location of the source electrode by minimizing a difference between respective pairs of determined source voltages for a plurality of

Assignees

• Cardioinsight Technologies Inc

Inventors

• Jia Ping
• Zeng Qingguo
• Ramanathan Charulatha
• Bokan Ryan

Classifications

• A61B5/0538

  invasively, e.g. using a catheter · CPC title

• A61B5/053

  Measuring electrical impedance or conductance of a portion of the body · CPC title

• A61B2560/0276

  Determining malfunction · CPC title

• A61B5/063 Primary

  using impedance measurements · CPC title

• A61B2560/0223

  of calibration, e.g. protocols for calibrating sensors · CPC title