Method for surgical navigation utilizing scale-invariant registration between a navigation system and a localization system

• US 7,555,331 B2
• Filed: 08/26/2004
• Issued: 06/30/2009
• Est. Priority Date: 08/26/2004
• Status: Active Grant

• Current Assignee: Stereotaxis, Inc.
• Original Assignee: Stereotaxis, Inc.
• Inventors: Viswanathan, Raju R.
• Primary Examiner(s): Casler; Brian
• Assistant Examiner(s): KISH, JAMES M
• Application Number:
  US10/926,782
• Publication Number:
  US 20060058646A1
• Time in Patent Office: 1,769 Days
• Field of Search: 600/407, 600/424
• US Class Current: 600/424
• CPC Class Codes: G06T 7/30 Determination of transform parameters for the alignment of images, i.e. image registration
• CPC Class Codes: G06T 7/73 using feature-based methods

Abstract

A system for navigating a medical device through the lumens and cavities in an operating region in a subject, comprising an imaging system for displaying an image of the operating region, including a representation of the distal end of the medical device in the operating region. The system also includes a localization system for determining the position of the medical device in a frame of reference translatable to the displayed image. Finally, the system includes an algorithm for evaluating one or more rotation matrix using a cost function to determine an optimum rotation matrix for performing transformation of a vector in the local frame of the localization system to that of the reference frame of the navigation system. The rotation matrix can then provide a scale invariant transformation or “registration” of the coordinate systems of the localization system and the navigation system. This allows navigation to be performed to a significant extent from the localization system display alone, which avoids the frequent x-ray irradiation that occurs during the use of fluoro imaging for navigation purposes.

Claims

1. A navigation system for navigating the distal end of a medical device in operating region in a subject, the system comprising:

an orientation system for orienting the distal end of the medical device in the operating region in response to inputs made by a user, the orientation system having an associated display of the operating region in a first coordinate reference frame;

a localization system for identifying locations in the operating region, the localization system having an associated display of the operating region and a first grid that establishes a second local coordinate reference frame different from the first coordinate reference frame, where the first grid is used to determine the coordinates of points projected from the display plane in the second local coordinate reference frame;

a control for accepting user inputs of a minimum number of points from the display of the localization system, which points have known three dimensional coordinates from the orientation system'"'"'s first coordinate frame of reference, the control including an algorithm for determining a transformation matrix for transforming inputs from the display of the localization system in the second local coordinate reference frame to inputs for the orientation system in the first coordinate reference frame;

wherein the algorithm performs a search in coordinate space to find a rotation matrix point that minimizes a cost function, where the search is performed by subdividing the coordinate space to establish a second grid defining a plurality of points, and the algorithm evaluates the points using a cost function to find a point at which an associated rotation matrix minimizes the cost function, to determine a rotation matrix point that yields a minimum cost function value; and

wherein the navigation system utilizes the determined rotation matrix to transform a displacement that is input to the localization system display into the navigation system'"'"'s first coordinate reference frame, to deploy a medical device to a desired location within the subject.

2. The navigation system according to claim 1 wherein the control accepts inputs of locations in the second reference frame from the display of the localization system and transforms them to inputs of locations in the first reference frame.

3. The navigation system according to claim 1 wherein the control accepts inputs of directions in the second reference frame from the display of the localization system and transforms them to inputs of directions in the first reference frame.

4. The navigation system according to claim 1 wherein the control uses a transformation derived from a cost function for evaluating a given rotation matrix that is a function of the ratios of the distances between the points in the first reference frame and distances between the corresponding points in the second reference frame.

5. The navigation system according to claim 4 wherein the ratio of distances is a ratio of distance magnitudes.

6. The navigation system according to claim 4 wherein the ratio of distances is a ratio of distance vectors.

7. The navigation system according to claim 1 wherein the localization system displays a representation of the surfaces in the operating region.

8. The navigation system according to claim 1 wherein the localization system displays a physiologic properties at locations on surfaces in the operating region.

9. A method of registering a display of an information system having first frame of reference with a navigation system having a second frame of reference frame, the method comprising:

identifying a set of points in an operating region on the display of the information system and a first grid that establishes the first frame of reference, where the first grid is used to determine the coordinates of points projected from the display in the first frame of reference;

identifying corresponding set of points in the second frame of reference, which corresponding set of points have known three dimensional coordinates in the navigation system'"'"'s second frame of reference;

determining a transformation between the first frame of reference and the second frame of reference using a rotation matrix that is a function of the ratios of distances among the identified points in the first frame of reference, and corresponding distances among the corresponding points identified in the second frame of reference, wherein the transformation is determined using an algorithm that performs a search in coordinate space to find a rotation matrix point that minimizes a cost function, where the search is performed by subdividing the coordinate space to establish a second grid defining a plurality of points, and the algorithm evaluates the points using a cost function to find a point at which an associated rotation matrix minimizes the cost function, to determine a rotation matrix point that yields a minimum cost function value; and

using the determined rotation matrix to transform an input to the display of the information system into coordinates of the navigation system'"'"'s second frame of reference, which coordinates are used by the navigation system.

10. The method according to claim 9 wherein the step of determining a transformation between the first frame of reference and the second frame of reference comprises finding the transformation using a cost function.

11. The method according to claim 10 wherein the transformation is a rotational transformation associated with a given increment.

12. A method of registering a display of an information system having first frame of reference with a navigation system having a second frame of reference frame, the method comprising:

identifying a set of points in the operating region on the display of the information system in the first frame of reference;

identifying corresponding set of points in the second frame of reference;

determining a transformation between the first frame of reference and the second frame of reference using a rotation matrix that is a function of the ratios of distances among the identified points in the first frame of references, and corresponding distances among the corresponding points identified in the second frame of reference, wherein the transformation is determined using an algorithm, which defines a plurality of points for which associated rotation matrices may be determined, and the step of determining a transformation between the first frame of reference and the second frame of reference comprises finding the transformation using a cost function over a range of values for determining an error associated with a given rotation matrix, in evaluating each rotation matrix to determine the rotation matrix that minimizes the cost function, to thereby identify a rotation matrix that will yield an accurate transformation;

wherein the cost function is a function of at least one transformation variable, and wherein step of determining a transformation between the first frame of reference and the second frame of reference using the cost function comprises evaluating the cost function over a range of values for the at least one transformation variable, taken at a first increment, and subsequently evaluating the cost function over a subset of the range of values taken at a second increment, smaller than the first increment.

13. A method of registering a display of an information system having first frame of reference with a navigation system having a second frame of reference frame, the method comprising:

identifying a set of points in the operating region on the display of the information system in the first frame of reference;

identifying corresponding set of points in the second frame of reference;

determining a transformation between the first frame of reference and the second frame of reference using a rotation matrix that is a function of the ratios of distances among the identified points in the first frame of references, and corresponding distances among the corresponding points identified in the second frame of reference, wherein the transformation is determined using an algorithm, which defines a plurality of points for which associated rotation matrices may be determined, and the step of determining a transformation between the first frame of reference and the second frame of reference comprises finding the transformation using a cost function over a range of values for determining an error associated with a given rotation matrix, in evaluating each rotation matrix to determine the rotation matrix that minimizes the cost function, to thereby identify a rotation matrix that will yield an accurate transformation;

wherein the cost function is a function of at least one transformation variable, and wherein step of determining a transformation between the first frame of reference and the second frame of reference using the cost function comprises an initial evaluation step of evaluating the cost function over a range of values for the at least one transformation variable, taken at a first increment, to determine the transformation that minimizes the cost function, and at least one subsequent refinement step of evaluating the cost function over a range of values for the at least one transformation variable around a previously determined step, at a smaller increment than previously used, to determine the transformation that minimizes the cost function.

14. A method of applying inputs from the display of an information system displaying information from an operating region in a subject utilizing a first frame of reference to a navigation system for orienting medical devices in the operating region in the subject utilizing a second frame of reference, the method comprising:

identifying a set of points in the operating region in the first frame of reference on a display of the information system, where a first grid is used to determine the coordinates of the set of points projected from the display in the first frame of reference, and identifying a corresponding set of points in the second frame of reference, which corresponding set of points have known three dimensional coordinates in the second frame of reference;

selecting a transformation that minimizes the errors in a rotation matrix that is determined as a function of ratios of corresponding distances among the points in each frame of reference using a subdivision method, wherein the transformation is selected by performing a search in coordinate space to find a rotation matrix point that minimizes a cost function, where the search is performed by subdividing the coordinate space to establish a second grid defining a plurality of points, and the points are evaluated using a cost function to find a point at which an associated rotation matrix minimizes the cost function, to determine a rotation matrix point that yields a minimum cost function value; and

using the determined rotation matrix in the transformation of an input to the display of the information system into coordinates of the navigation system'"'"'s second frame of reference, which coordinates are used by the navigation system in orienting medical devices in the operating region.

15. The method according to claim 14 wherein the ratio of corresponding distances is a ratio of distance magnitudes.

16. The method according to claim 14 wherein the ratio of corresponding distances is a ration of distance vectors.

17. A method of controlling a navigation system operating in a first reference frame to orient the distal end of medical device in an operating region in a direction based upon user inputs, to an information system with a display of the operating region using a first grid that establishes a second reference frame, the method comprising:

identifying a set of points in the second reference frame on the information system'"'"'s display using a first grid, where the first grid is used to determine the coordinates of the set of points projected from the display in the second reference frame, and identifying a set of points in the first reference frame corresponding to the set of points in the second reference frame;

transforming inputs in the second reference frame to the first reference frame using a transformation derived from corresponding points selected in each frame of reference, wherein a transformation is determined by performing a search in coordinate space to find a rotation matrix point that minimizes a cost function, where the search is performed by subdividing the coordinate space to establish a second grid defining a number of points for which associated rotation matrices may be determined as a function of ratios of distances among the selected points, and the points are evaluated using a cost function to find a point at which an associated rotation matrix minimizes the cost function, to determine a rotation matrix point that yields a minimum cost function value; and

using the determined transformation including the rotation matrix in transforming an input to the information system into coordinates of the navigation system'"'"'s first frame of reference that are used by the navigation system in orienting the medical device in the operating region.

18. The method according to claim 17 wherein the transformation is determined using a cost function.

19. The method according to claim 18 wherein the cost function utilizes ratios of distances among corresponding points in each of the reference frames.

20. The method according to claim 17 wherein the ratio of distances is a ratio of distance magnitudes.

21. The method according to claim 17 wherein the ratio of distances is a ration of distance vectors.

22. A method of controlling a navigation system operating in a first reference frame to orient the distal end of medical device in an operating region in a direction based upon user inputs from a system with a display of the operating region in a second reference frame, the method comprising:

transforming inputs in the second reference frame to the first reference frame using a transformation derived from corresponding points selected in each frame of reference, wherein a transformation is determined by defining a number of points for which associated rotation matrices may be determined as a function of ratios of distances among the selected points, and evaluated using a cost function to find a rotation matrix that will yield an accurate transformation, wherein the transformation is determined using a cost function that is minimized using a subdivision method.

23. A system for controlling navigation of a medical device through the lumens and cavities in an operating region in a subject, the system comprising:

a navigation system for orienting the medical device in a selected direction in the operating region in the subject, having a display for displaying images of the operating region in a first coordinate reference frame;

an imaging system for displaying and transferring to the navigation system an image of the operating region;

a localization system for determining the position of the medical device, having a display for showing the position of the medical device;

a marking system for marking locations on a localization system display, the system including a first grid that establishes a second coordinate reference frame, where the first grid is used to determine the coordinates of the marked locations on the display in the second coordinate reference frame;

an input device for defining desired device positioning information with respect to the localization system display as input to the navigation system; and

a controller, responsive to inputs by the user of a plurality of location points on the localization system display in the second coordinate reference frame, wherein the controller is configured to determine a transformation, from the second coordinate reference frame to the first coordinate reference frame, using an algorithm which performs a search in coordinate space to find a rotation matrix point that minimizes a cost function, where the search is performed by subdividing the coordinate space to establish a second grid that defines a plurality of points for which associated rotation matrices may be determined as a function of ratios of distances among the marked locations on the display, and uses a cost function over a range of values for determining an error associated with a given rotation matrix, wherein the algorithm evaluates the points using the cost function to find a point at which an associated rotation matrix minimizes the cost function, to determine a rotation matrix point that yields a minimum cost function value; and

wherein the controller is configured to perform a transformation of the desired input information to provide control variable information to the navigation system for actuation and control of the distal end of the medical device.

24. The system of claim 23, where the marking system is used to register the localization system display to the navigation system.

25. The system of claim 23, where the desired device positioning information defined is directional information.

26. The system of claim 23, where the desired device positioning information defined is displacement information.

27. The system of claim 23, where the desired device positioning information defined is destination coordinates information for the distal tip of the device.

28. The system of claim 23, where the marking system is based on a touch screen.

29. The system of claim 23, wherein the input device is further capable of input of coordinate information of a minimum number of location points input by the user.

30. The system of claim 29, wherein the controller further utilizes an algorithm for interpreting a minimum number of data point inputs from the user, and responsively determining an optimum transformation of subsequent input of device positioning information for use by the navigation system.

31. The system of claim 30, wherein the algorithm further uses a cost function constructed from ratios of distances between data points, which is used to evaluate one or more rotation matrix for obtaining the optimum rotation matrix with the least cost function value.

32. The system of claim 23, wherein the device positioning information is a specification of device configuration.

33. The system of claim 23, wherein the input device comprises a joystick that enables the user to input device positioning information.

34. The system of claim 23, wherein the input device comprises a computer mouse that enables the user to input device positioning information.

35. The system of claim 23, wherein the input device comprises a localized hand-held stylus that enables the user to input device positioning information.

36. The system of claim 23, wherein the input device comprises a touch screen apparatus on the display of the localization system that enables the user to input device positioning information.

37. The system of claim 23, wherein the device positioning information is a specification of device configuration.

38. A system for controlling navigation of a medical device through the lumens and cavities in an operating region in a subject, the system comprising:

an elongate medical device, having a proximal end and a distal end adapted to be introduced into the operating region;

a navigation system for orienting the medical device in a selected direction in the operating region in the subject, and displaying images of the operating region in a first coordinate reference frame;

an imaging system for displaying and transferring to the navigation system an image of the operating region;

a localization system for determining the position of the medical device, having a display for showing the position of the medical device, and a first grid that establishes a second local coordinate reference frame, where the first grid is used to determine the coordinates of the set of points projected from the display in the second local coordinate reference frame;

a marking system for marking locations on the localization system display;

an input device for defining desired device positioning information with respect to the localization system display as input to the navigation system; and

a controller, responsive to inputs by the user of a plurality of location points on the localization system display in the second local coordinate reference frame, wherein the controller is configured to determine a transformation, from the second coordinate reference frame to the first coordinate reference frame, using an algorithm that performs a search in coordinate space to find a rotation matrix point that minimizes a cost function, where the search is performed by subdividing the coordinate space to establish a second grid that defines a plurality of points for which associated rotation matrices may be determined as a function of ratios of distances among the marked locations on the display, and uses a cost function over a range of values for determining an error associated with a given rotation matrix, wherein the algorithm evaluates the points using the cost function to find a point at which an associated rotation matrix minimizes the cost function, to determine a rotation matrix point that yields a minimum cost function value; and

wherein the controller is configured to perform a translation of the desired input information to provide control variable information to the navigation system for actuation and control of the distal end of the medical device.

39. The system of claim 38, where the desired device positioning information defined is directional information.

40. The system of claim 38, where the desired device positioning information defined is displacement information.

41. The system of claim 38, where the desired device positioning information defined is destination coordinates information for the distal tip of the device.

42. The system of claim 38, wherein the control utilizes an algorithm for interpreting a minimum number of data point inputs from the user, and responsively determining an optimum transformation of subsequent input of device positioning information for use by the navigation system.

43. The system of claim 42, wherein the algorithm further uses a cost function constructed from ratios of distances between data points, which is used to evaluate one or more rotation matrix for obtaining the optimum rotation matrix with the least cost function value.

44. A method of controlling a system for navigation of a medical device through an operating region in a subject, comprising a navigation system with a display of at least one image of the operating region, a localization system with a display and a first grid that establishes a second coordinate frame of reference, and an input device for defining desired device positioning information with respect to the localization system display as input to the navigation system, the method comprising the steps of:

identifying at least a minimum number of points on the image display of the navigation system that have known coordinates within the first coordinate reference frame of the navigation system;

identifying at least a minimum number of corresponding point locations on the localization display and identifying the coordinates of the corresponding point locations in the second coordinate reference frame, where the first grid is used to determine the coordinates of the corresponding point locations on the localization display in the second coordinate reference frame;

receiving the input of coordinates in the second coordinate reference frame to the navigation system for each of the known point locations identified on the localization display; and

using an algorithm that uses the known point location information input into the navigation system to compute a transformation of device positioning information in the second coordinate reference frame into navigation system coordinates in the first coordinate reference frame for controlling the operation of the navigation system, said algorithm performing a search in coordinate space to find a rotation matrix point that minimizes a cost function, where the search is performed by subdividing the coordinate space to establish a second grid that defines a plurality of points for which associated rotation matrices may be determined as a function of ratios of distances among the known point locations, wherein the algorithm evaluates the points using the cost function to find a point at which an associated rotation matrix minimizes the cost function, to determine a rotation matrix point that yields a minimum cost function value; and

using the determined rotation matrix to transform the desired device positioning information in the second coordinate reference frame into coordinates of the navigation system'"'"'s first frame of reference, which are used in navigation of the medical device in the operating region.

45. A method of controlling a system for navigation of a medical device through an operating region in a subject, having a navigation system, an imaging system, a localization system with a display and a first grid that establishes a second coordinate reference frame, and an input device for specification of device positioning information relative to the localization display, the method comprising the steps of:

identifying a minimum number of points on the imaging system that have known coordinates within the first coordinate reference frame of the navigation system;

identifying corresponding point locations on the localization display of the minimum number of points having known coordinates in the first coordinate reference frame;

using the first grid to determine the coordinates of the corresponding point locations on the localization display in the second coordinate reference frame; and

inputting the coordinates in the second coordinate reference frame into the localization system for each of the known point locations;

using an optimization algorithm to determine a rotation matrix that will yield a transformation between the second coordinate reference frame of the localization display and navigation system coordinates, where the optimization algorithm performs a search, in coordinate space to find a rotation matrix point that minimizes a cost function, by subdividing the coordinate space to establish a second grid defining a plurality of points, and the algorithm evaluates the points using a cost function to find a point at which an associated rotation matrix minimizes the cost function, to determine a rotation matrix point that yields a minimum cost function value; and

using the determined rotation matrix to transform an input of device positioning information to the localization display in the second coordinate reference frame into coordinates of the navigation system'"'"'s first frame of reference, which coordinates are used by the navigation system.

46. A system for navigating the distal end of an elongate medical device in an operating region in a subject, the system comprising:

an elongate medical device, having a proximal end and a distal end adapted to be inserted into the body;

a navigation system for remotely orienting the distal end of the medical device in a selected direction in the operating region;

a localization system for determining the position of the medical device having a display and a first grid for establishing a second local coordinate reference frame;

an input means of specifying in coordinate information on the navigation system;

an input means for specifying coordinate information of a number of points displayed on the localization system display where the first grid is used to determine the coordinates of the number of points on the localization system display in the second local coordinate reference frame;

an input means for specifying desired device positioning information; and

a control that is configured for;

receiving the coordinates of a minimum number of known point locations on the localization display;

receiving an input of desired device positioning information in the operating region;

wherein the control is configured to use an optimization algorithm to determine a transformation of the device positioning information in the second coordinate reference frame to navigation system coordinates in a first coordinate reference frame, said algorithm performing a search in coordinate space to find a rotation matrix point that minimizes a cost function, where the search is performed by subdividing the coordinate space to establish a second grid defining a plurality of points, said algorithm evaluating the points using a cost function to find a point at which an associated rotation matrix minimizes the cost function, to determine a rotation matrix point that yields a minimum cost function value; and

wherein the controller is configured to perform the transformed device positioning data in the second coordinate reference frame to the navigation system first coordinate reference frame to responsively move the medical device to the desired destination.