Reduced field distortion in medical tools

• US 20070255132A1
• Filed: 04/28/2006
• Published: 11/01/2007
• Est. Priority Date: 04/28/2006
• Status: Active Grant

• Current Assignee: Biosense Webster Incorporated (Johnson & Johnson)
• Original Assignee: Biosense Webster Incorporated (Johnson & Johnson)
• Inventors: Shalgi, Avi, Nitzan, Yaacov, Yaron, Uri, Bar- Tal, Meir
• Granted Patent: US 9,364,293 B2
• Time in Patent Office: Days
• US Class Current: 600/424
• CPC Class Codes: A61B 2034/2051 Electromagnetic tracking systems
• CPC Class Codes: A61B 2090/3958 emitting a signal
• CPC Class Codes: A61B 34/20 Surgical navigation systems; Devices for tracking or guiding surgical instruments, e.g. for frameless stereotaxis
• CPC Class Codes: A61B 5/06 Devices, other than using radiation, for detecting or locating foreign bodies for removing same A61B17/50 ; determining position of probes within or on the body of the patient
• CPC Class Codes: A61B 5/062 using magnetic field
• CPC Class Codes: A61B 90/36 Image-producing devices or illumination devices not otherwise provided for
• CPC Class Codes: G01V 3/104 using several coupled or uncoupled coils G01V3/101 takes precedence

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. Another medical tool includes a core including a ferromagnetic material and an outer coating layer on the core. The coating layer includes a conductive material configured to produce eddy current distortion so as to cancel at least part of a distortion caused by the core in a magnetic field of the magnetic position tracking system. Yet another medical tool includes 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.

Claims

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 one of the field transducers is coupled to an object for insertion into the body; and

a control unit, which is arranged to process the signal so as to determine a position of the object; and

a medical tool for use in the treatment of 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.

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 object 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 object.

11. The system according to claim 1, wherein the first field transducer comprises a field generator coupled to the object, 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 one of the field transducers is coupled to an object for insertion into the body; and

a control unit, which is arranged to process the signal so as to determine a position of the object; and

a medical tool for use in the treatment of 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.

13. The system according to claim 12, wherein the medical tool comprises an orthopedic tool, and wherein the object 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 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 one of the field transducers is coupled to an object for insertion into the body; and

a control unit, which is arranged to process the signal so as to determine a position of the object; and

a medical tool for use in the treatment of the body, the tool comprising 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.

18. The system according to claim 17, wherein the loop-shaped element comprises at least one of a handle and a loop-shaped cross-section of the tool.

19. 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.

20. The tool according to claim 19, wherein the layers in the first and second pluralities respectively comprise first and second planar layers.

21. The tool according to claim 19, 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.

22. The tool according to claim 19, 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.

23. The tool according to claim 19, wherein the medical tool comprises an orthopedic tool for use with orthopedic implants.

24. The tool according to claim 19, 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.

25. The tool according to claim 19, 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.

26. The tool according to claim 19, 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.

27. 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 magnetic field generated by the magnetic position tracking system.

28. The tool according to claim 27, wherein the medical tool comprises an orthopedic tool for use with orthopedic implants.

29. The tool according to claim 27, wherein the outer coating layer comprises copper.

30. The tool according to claim 27, 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.

31. The tool according to claim 27, 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 system.

32. A medical tool for operating in a working volume of a magnetic position tracking system, the tool comprising 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 a magnetic field generated by the magnetic position tracking system.

33. The tool according to claim 32, wherein the loop-shaped element comprises at least one of a handle and a loop-shaped cross-section of the tool.

34. A method for treatment of a body of a patient, comprising:

generating a magnetic field using a first field transducer;

sensing the magnetic field using a second field transducer, wherein one of the field transducers is coupled to an object in the body, so as to determine a position of the object; and

treating the body using a medical tool, which comprises 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.

35. The method according to claim 34, wherein the layers in the first and second pluralities respectively comprise first and second planar layers.

36. The method according to claim 34, 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.

37. The method according to claim 34, 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.

38. The method according to claim 34, wherein treating the body comprises performing an orthopedic procedure using the tool.

39. The method according to claim 34, 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.

40. The method according to claim 34, 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 some of a distortion caused by the core in the magnetic field sensed by the second field transducer.

41. The method according to claim 34, 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 sensed by the second field transducer.

42. The method according to claim 34, and comprising determining a position of the medical tool using a third field transducer coupled to the medical tool.

43. The method according to claim 34, 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 object.

44. The method according to claim 34, wherein the first field transducer comprises a field generator coupled to the object, and wherein the second field transducer comprises a position sensor external to the body.

45. A method for treatment of a body of a patient, comprising:

generating a magnetic field using a first field transducer;

sensing the magnetic field using a second field transducer, wherein one of the field transducers is coupled to an object in the body, so as to determine a position of the object; and

treating the body using a medical tool, which 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 some of a distortion caused by the core in the magnetic field sensed by the second field transducer.

46. The method according to claim 45, wherein treating the body comprises performing an orthopedic procedure using the tool.

47. The method according to claim 45, wherein the outer coating layer comprises copper.

48. The method according to claim 45, 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.

49. The method according to claim 45, 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 sensed by the second field transducer.

50. A method for treatment of a body of a patient, comprising:

generating a magnetic field using a first field transducer;

sensing the magnetic field using a second field transducer, wherein one of the field transducers is coupled to an object in the body, so as to determine a position of the object; and

treating the body using a medical tool, which 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.

51. The method according to claim 50, wherein the loop-shaped element comprises at least one of a handle and a loop-shaped cross-section of the tool.

52. A method for manufacturing a medical tool for operating in a working volume of a magnetic position tracking system, the method comprising:

forming a first plurality of layers comprising an electrically conductive material; and

interleaving the first plurality with a second plurality of layers comprising an electrically insulating material, wherein the layers are arranged to reduce eddy current distortion in a magnetic field generated by the magnetic position tracking system.

53. The method according to claim 52, wherein the layers in the first and second pluralities respectively comprise first and second planar layers.

54. The method according to claim 52, 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.

55. The method according to claim 52, wherein forming the first plurality of layers comprises introducing an electrical discontinuity into at least one of the layers in the first plurality so as to reduce the eddy current distortion.

56. A method for manufacturing a medical tool for operating in a working volume of a magnetic position tracking system, the method comprising:

forming a core of the tool, the core comprising a ferromagnetic material; and

coating the core with an outer coating layer, the coating layer comprising a conductive material configured to produce eddy current distortion so as to cancel at least part of a distortion caused by the core when subjecting the tool to a magnetic field in the working volume.

57. The method according to claim 56, wherein coating the core comprises applying a pattern of slots in the outer coating layer, so as to control a formation of the eddy current distortion caused by the coating layer.

58. A method for manufacturing a medical tool for operating in a working volume of a magnetic position tracking system, the method comprising:

identifying an electrically conducting loop-shaped element in the tool; and

introducing an electrical discontinuity into the loop-shaped element, so as to reduce eddy current distortion caused by the loop-shaped element in a magnetic field generated by the magnetic position tracking system.

59. The method according to claim 58, wherein the loop-shaped element comprises at least one of a handle and a loop-shaped cross-section of the tool.