Linking of an intra-body tracking system to external reference coordinates

• US 6,574,498 B1
• Filed: 04/27/2001
• Issued: 06/03/2003
• Est. Priority Date: 09/16/1999
• Status: Expired due to Term

• Current Assignee: Covidien LP (Medtronic Plc)
• Original Assignee: Super Dimension Ltd.
• Inventors: Gilboa, Pinhas
• Primary Examiner(s): Smith, Ruth S.
• Application Number:
  US09/830,484
• Time in Patent Office: 767 Days
• Field of Search: 600/424, 600/407, 600/437, 600/427, 600/438, 128/899, 607/122
• US Class Current: 600/424
• CPC Class Codes: A61B 2034/2051 Electromagnetic tracking systems
• CPC Class Codes: A61B 2034/2053 Tracking an applied voltage gradient
• CPC Class Codes: A61B 2090/0818 Redundant systems, e.g. using two independent measuring systems and comparing the signals
• 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 6/12 Arrangements for detecting or locating foreign bodies
• CPC Class Codes: A61B 8/0833 involving detecting or locating foreign bodies or organic structures
• CPC Class Codes: A61B 8/0841 for locating instruments

Abstract

A method, and system for determining the position, and optionally, the orientation of a work piece such as a catheter within a cavity of an opaque body such as a patient. The position, and orientation are to be determined relative to a primary coordinate system, for example, the coordinate system of an imaging device. Using a primary reference transducer (210) that interacts with a primary field, and several secondary reference transducers (310) that interact with a secondary field, the coordinates of the secondary reference transducers are determined in the primary coordinate system.

Claims

1. A method for determining a position and an orientation of a workpiece relative to a primary coordinate system, comprising the steps of:

(a) providing a primary reference transducer that interacts with a primary field;

(b) providing a plurality of secondary reference transducers that interact with a secondary field different from said primary field, said secondary transducers being in a fixed mutual spatial relationship so as to define a secondary coordinate system, said primary reference transducer being in a fixed spatial relationship to said secondary transducers;

(c) measuring at least one value of said primary field, using said primary reference transducer;

(d) inferring, from said at least one value of said primary field, a position and an orientation of said reference transducers relative to the primary coordinate system, thereby determining a position and an orientation of said secondary coordinate system relative to the primary coordinate system;

(e) providing the workpiece with at least one workpiece transducer that interacts with said secondary field;

(f) measuring a plurality of values of said secondary field, using said secondary reference transducers and said workpiece transducer;

(g) inferring, from said values of said secondary field, a first measure of a position of the workpiece relative to said secondary coordinate system; and

(h) combining said first measure of said position of the workpiece relative to said secondary coordinate system with said position and said orientation of said secondary coordinate system relative to the primary coordinate system to provide the position and the orientation of the workpiece relative to the primary coordinate system.

2. The method of claim 1, wherein said primary field is a vector field.

3. The method of claim 2, wherein said primary field is an electromagnetic field.

4. The method of claim 1, wherein said secondary field is a scalar field.

5. The method of claim 4, wherein said secondary field is an acoustic field.

6. The method of claim 5, wherein each of said secondary reference transducers and each of said at least one workpiece transducer includes a piezoelectric crystal.

7. The method of claim 4, wherein said secondary field is an electric potential field.

8. The method of claim 7, wherein each of said secondary reference transducers and each of said at least one workpiece transducer includes an electrode.

9. The method of claim 1, further comprising the step of:

(i) calibrating said inferring of said first measure of said position of the workpiece.

10. The method of claim 9, wherein said calibrating includes the steps of:

(i) providing the workpiece with at least one calibration transducer that interacts with said primary field and that is in a fixed spatial relationship to said at least one workpiece transducer,

(ii) measuring at least one value of said primary field, using said calibration transducer, and

(iii) inferring, from said at least one value of said primary field, a position and an orientation of the workpiece relative to said primary coordinate system.

11. The method of claim 10, wherein said calibrating further includes the step of:

(iv) inferring, from said position and said orientation of the workpiece relative to said primary coordinate system, and from said position and said orientation of said secondary coordinate system relative to the primary coordinate system, a second measure of said position of the workpiece relative to said secondary coordinate system.

12. The method of claim 1, wherein the workpiece is provided with a plurality of said workpiece transducers, the method further comprising the step of:

(i) inferring, from said values of said secondary field, an orientation of the workpiece relative to said secondary coordinate system.

13. A method of navigating a probe inside a body, comprising the steps of:

(a) providing a primary reference transducer that interacts with a primary field;

(b) providing a plurality of secondary reference transducers that interact with a secondary field different from said primary field, said secondary transducers being in a fixed mutual spatial relationship and in a fixed spatial relationship to the body, said primary reference transducer being in a fixed spatial relationship to said secondary transducers;

(c) providing a device for acquiring an image of the body;

(d) simultaneously;

(i) acquiring said image of the body,

(ii) measuring at least one value of said primary field, using said primary reference transducer, and

(iii) inferring, from said at least one value of said primary field, a position and an orientation of said reference transducers relative to the device, thereby determining a position and an orientation of the body relative to the image;

(e) determining a position of the probe relative to the body by;

(i) providing the probe with at least one probe transducer that interacts with said secondary field;

(ii) measuring a plurality of values of said secondary field, using said secondary reference transducers and said probe transducer, and

(iii) inferring, from said values of said secondary field, said position of the probe relative to the body; and

(f) displaying said image of the body with a representation of the probe superposed thereon according to said positions and said orientation.

14. The method of claim 13, wherein said primary field is a vector field.

15. The method of claim 14, wherein said primary field is an electromagnetic field.

16. The method of claim 13, wherein said secondary field is a scalar field.

17. The method of claim 16, wherein said secondary field is an acoustic field.

18. The method of claim 17, wherein each of said secondary reference transducers and each of said at least one probe transducer includes a piezoelectric crystal.

19. The method of claim 16, wherein said secondary field is an electric potential field.

20. The method of claim 19, wherein each of said secondary reference transducers and each of said at least one probe transducer includes an electrode.

21. The method of claim 13, wherein said image is selected form the group of modalities consisting of CT, MRI, ultrasound and fluoroscopy.

22. A system for navigating a probe through an opaque body, comprising:

(a) a primary reference transducer that interacts with a primary field;

(b) a plurality of secondary reference transducers that interact with a secondary field, said secondary field being an electric potential field;

(c) a mechanism for deploying said reference transducers in a fixed mutual spatial relationship; and

(d) at least one probe transducer, having a fixed spatial relationship to the probe, that interacts with said secondary field,

wherein each of said secondary reference transducers and each of said at least one probe transducer includes an electrode.

23. The system of claim 22, wherein said mechanism includes a reference object to which said reference transducers are rigidly attached.

24. The system of claim 22, wherein said at least one probe transducer is rigidly attached to said probe.

25. The system of claim 22, further comprising:

(e) at least one calibration transducer that interacts with said primary field and that has a fixed spatial relationship to said at least one probe transducer.

26. A method for determining a position and an orientation of a first workpiece relative to both a second workpiece and a primary coordinate system, comprising the steps of:

(a) providing the second workpiece with at least one primary transducer that interacts with a primary field and that defines a workpiece coordinate system that is fixed with respect to the second workpiece;

(b) providing a mechanism for generating a secondary field and for defining a secondary coordinate system;

(c) providing the first workpiece with at least one secondary transducer that interacts with said secondary field;

(d) providing a transformation from said secondary coordinate system to said workpiece coordinate system;

(e) measuring at least one value of said secondary field, using said at least one secondary transducer;

(f) inferring, from said at least one value of said secondary field, a position of the first workpiece relative to said secondary coordinate system;

(g) measuring at least one value of said primary field, using said at least one primary transducer;

(h) inferring, from said at least one value of said primary field, a position and an orientation of said at least one primary transducer relative to the primary coordinate system, thereby providing a transformation from said workpiece coordinate system to the primary coordinate system;

(i) combining said position of the first workpiece relative to said secondary coordinate system with said transformation from said secondary coordinate system to said workpiece coordinate system to provide the position and the orientation of the first workpiece relative to the second workpiece; and

(j) combining the position and the orientation of the first workpiece relative to the second workpiece with said transformation from said workpiece coordinate system to the primary coordinate system to provide the position and the orientation of the first workpiece relative to the primary coordinate system.

27. The method of claim 26, wherein said primary field is a vector field.

28. The method of claim 27, wherein said primary field is an electromagnetic field.

29. The method of claim 28, wherein said secondary field is a scalar field.

30. The method of claim 29, wherein said secondary field is an electric potential field.

31. The method of claim 30, wherein each of said at least one workpiece transducer includes an electrode.

32. The method of claim 26, wherein said providing of said transformation from said secondary coordinate system to said workpiece coordinate system includes the steps of:

(i) providing the first workpiece with at least one calibration transducer that interacts with said primary field and that is in a fixed spatial relationship to said at least one workpiece transducer;

(ii) simultaneously measuring a plurality of values of said primary field, using said at least one primary transducer and said calibration transducer; and

(iii) inferring, from said simultaneously measured plurality of values of said primary field, positions and orientation of both workpieces with respect to the primary field.

33. A method of navigating a probe inside a body, comprising the steps of:

(a) providing a device for acquiring an image of the body;

(b) providing the body with at least one body transducer that is in a fixed spatial relationship to the body and that interacts with a primary field;

(c) simultaneously;

(i) acquiring said image of the body,

(ii) measuring at least one value of said primary field, using said at least one body transducer, and

(iii) inferring, from said at least one value of said primary field, a position and an orientation of said at least one body transducer relative to the device, thereby determining a position and an orientation of the body relative to the image;

(d) determining a position of the probe relative to the body by;

(i) providing the probe with at least one probe transducer that interacts with a secondary field;

(ii) measuring a plurality of values of said secondary field, using said at least one probe transducer, and

(iii) inferring, from said values of said secondary field, said position of the probe relative to the body; and

(e) displaying said image of the body with a representation of the probe superposed thereon according to said positions and said orientation.

34. The method of claim 33, wherein said primary field is a vector field.

35. The method of claim 34 wherein said primary field is an electromagnetic field.

36. The method of claim 33, wherein said secondary field is a scalar field.

37. The method of claim 36, wherein said secondary field is an electric potential field.

38. The method of claim 37, wherein each of said probe transducers includes an electrode.

39. The method of claim 33, wherein said image is selected from the group of modalities consisting of CT, MRI, ultrasound and fluoroscopy.