Reduced field distortion in medical tools

Patent metadata

Field	Value
Publication number	US-9364293-B2
Application number	US-41444906-A
Country	US
Kind code	B2
Filing date	Apr 28, 2006
Priority date	Apr 28, 2006
Publication date	Jun 14, 2016
Grant date	Jun 14, 2016

Abstract

A medical tool for operating in a working volume of a magnetic position tracking system includes a first plurality of layers including an electrically conductive material and a second plurality of layers including an electrically insulating material and interleaved with the first plurality. The layers are arranged to reduce eddy current distortion in a magnetic field generated by the magnetic position tracking system.

First claim

The invention claimed is:

1. A system for treatment of a body of a patient, comprising:
a magnetic position tracking system, comprising:
a first field transducer, which is arranged to generate a magnetic field;
a second field transducer, which is arranged to sense the magnetic field and generate a signal responsively to the sensed field,
wherein the second field transducers is coupled to an implant for insertion into the body; and
a control unit, which is arranged to process the signal so as to determine a position of the implant in the body; and

a medical tool for use in the body, the tool comprising a first plurality of layers comprising an electrically conductive material, interleaved with a second plurality of layers comprising an electrically insulating material, wherein the layers are arranged to reduce eddy current distortion in the magnetic field sensed by the second field transducer coupled to the implant.

2. The system according to claim 1 , wherein the layers in the first and second pluralities respectively comprise first and second planar layers.

3. The system according to claim 1 , wherein the tool has an axis, and wherein the layers in the first and second pluralities respectively comprise first and second annular layers surrounding the axis.

4. The system according to claim 1 , wherein at least one of the layers in the first plurality has an electrical discontinuity introduced therein so as to reduce the eddy current distortion.

5. The system according to claim 1 , wherein the medical tool comprises an orthopedic tool, and wherein the implant comprises an orthopedic implant.

6. The system according to claim 1 , wherein the second plurality of layers comprises at least one of an adhesive material applied between the first plurality of layers and an electrically insulating coating layer applied to the first plurality of layers.

7. The system according to claim 1 , wherein the tool comprises a core comprising a ferromagnetic material and an outer coating layer on the core, the coating layer comprising a conductive material configured so as to produce eddy current distortion responsively to the magnetic field so as to cancel at least part of a distortion caused by the core in the magnetic field sensed by the second field transducer.

8. The system according to claim 1 , wherein the tool comprises an electrically conducting loop-shaped element having an electrical discontinuity introduced therein so as to reduce eddy current distortion caused by the loop-shaped element in the magnetic field sensed by the second field transducer.

9. The system according to claim 1 , and comprising a third field transducer coupled to the medical tool, wherein the control unit is further arranged to determine a position of the medical tool using the third field transducer.

10. The system according to claim 1 , wherein the first field transducer comprises a field generator external to the body, and wherein the second field transducer comprises a position sensor coupled to the implant.

11. The system according to claim 1 , wherein the first field transducer comprises a field generator coupled to the implant, and wherein the second field transducer comprises a position sensor external to the body.

12. A system for treatment of a body of a patient, comprising:
a magnetic position tracking system, comprising:
a first field transducer, which is arranged to generate a magnetic field;
a second field transducer, which is arranged to sense the magnetic field and generate a signal responsively to the sensed field,
wherein second the field transducers is coupled to an implant for insertion into the body; and
a control unit, which is arranged to process the signal so as to determine a position of the implant in the body; and

a medical tool for use in the body, the tool comprising a core comprising a ferromagnetic material and an outer coating layer on the core, the coating layer comprising a conductive material configured to produce eddy current distortion responsively to the magnetic field so as to cancel at least part of a distortion caused by the core in the magnetic field sensed by the second field transducer coupled to the implant.

13. The system according to claim 12 , wherein the medical tool comprises an orthopedic tool, and wherein the implant comprises an orthopedic implant.

14. The system according to claim 12 , wherein the outer coating layer comprises copper.

15. The system according to claim 12 , wherein the outer coating layer has a pattern of slots formed therein so as to control a formation of the eddy current distortion caused by the coating layer.

16. The system according to claim 12 , wherein the tool comprises an electrically conducting loop-shaped element having an electrical discontinuity introduced therein so as to reduce eddy current distortion caused by the loop-shaped element in the magnetic field sensed by the second field transducer.

17. A medical tool for operating in a working volume of a magnetic position tracking system, the tool comprising:
a first plurality of layers comprising an electrically conductive material; and
a second plurality of layers comprising an electrically insulating material and interleaved with the first plurality, wherein the layers are arranged to reduce eddy current distortion in a magnetic field generated by the magnetic position tracking system.

18. The tool according to claim 17 , wherein the layers in the first and second pluralities respectively comprise first and second planar layers.

19. The tool according to claim 17 , wherein the tool has an axis, and wherein the layers in the first and second pluralities respectively comprise first and second annular layers surrounding the axis.

20. The tool according to claim 17 , wherein at least one of the layers in the first plurality has an electrical discontinuity introduced therein so as to reduce the eddy current distortion.

21. The tool according to claim 17 , wherein the medical tool comprises an orthopedic tool for use with orthopedic implants.

22. The tool according to claim 17 , wherein the second plurality of layers comprises at least one of an adhesive material applied between the first plurality of layers and an electrically insulating coating layer applied to the first plurality of layers.

23. The tool according to claim 17 , wherein the tool further comprises a core comprising a ferromagnetic material and an outer coating layer on the core, the coating layer comprising a conductive material configured to produce eddy current distortion responsively to the magnetic field so as to cancel at least part of a distortion caused by the core in the magnetic field generated by the magnetic position tracking system.

24. The tool according to claim 17 , wherein the tool further comprises an electrically conducting loop-shaped element having an electrical discontinuity introduced therein so as to reduce eddy current distortion caused by the loop-shaped element in the magnetic field generated by the magnetic position tracking system.

25. A medical tool for operating in a working volume of a magnetic position tracking system, the tool comprising:
a core comprising a ferromagnetic material; and
an outer coating layer on the core, the coating layer comprising a conductive material configured to produce eddy current distortion responsively to the magnetic field so as to cancel at least part of a distortion caused by the core in a m

Assignees

• Shalgi Avi
• Nitzan Yaacov
• Bar-Tal Meir
• Yaron Uri
• Biosense Webster Inc

Inventors

• Shalgi Avi
• Nitzan Yaacov
• Bar-Tal Meir
• Yaron Uri

Classifications

• A61B34/20 Primary

  Surgical navigation systems; Devices for tracking or guiding surgical instruments, e.g. for frameless stereotaxis · CPC title

• A61B2034/2051

  Electromagnetic tracking systems · CPC title

• A61B90/36

  Image-producing devices or illumination devices not otherwise provided for · CPC title

• G01V3/104

  using several coupled or uncoupled coils (G01V3/101 takes precedence) · CPC title

• A61B2090/3958

  emitting a signal · CPC title