System and methods for intraoperative guidance feedback
Systems and methods for surgical guidance and image registration are provided, in which three-dimensional image data associated with an object or patient is registered to topological image data obtained using a surface topology imaging device. The surface topology imaging device may be rigidly attached to an optical position measurement system that also tracks fiducial markers on a movable instrument. The instrument may be registered to the topological image data, such that the topological image data and the movable instrument are registered to the three-dimensional image data. The three-dimensional image data may be CT or MRI data associated with a patient. The system may also co-register images pertaining to a surgical plan with the three-dimensional image data. In another aspect, the surface topology imaging device may be configured to directly track fiducial markers on a movable instrument. The fiducial markers may be tracked according to surface texture.
1. A method of determining a calibration transform between a first frame of reference associated with a surface topology imaging device and a second frame of reference associated with an optical tracking system, the method comprising the steps of:
positioning three or more fiducial markers such that they reside within respective fields of view of both the surface topology imaging device and the optical tracking system, and such that the fiducial markers are stationary with respect to one another;
employing the surface topology imaging device to scan the fiducial markers and acquire surface data;
processing the surface data to locate each fiducial marker in the first frame of reference;
employing the optical tracking system to track the fiducial markers and locate each fiducial marker in the second frame of reference; and
registering the locations of the fiducial markers in the first frame of reference with the locations of the fiducial markers in the second frame of reference, thereby obtaining the calibration transform between the first frame of reference and the second frame of reference.
2. The method according to claim 1 wherein the step of processing the surface data to locate a given optical tracking fiducial marker in the first frame of reference comprises:
segmenting the surface data to obtain segmented surface data associated with the given optical tracking fiducial marker; and
processing the segmented surface data to locate the given optical tracking fiducial marker in the first frame of reference.
3. The method according to claim 2 wherein the segmented surface data associated with the given optical tracking fiducial marker is processed to determine a center location of the given optical tracking fiducial marker in the first frame of reference.
4. The method according to claim 3 wherein the given optical tracking fiducial marker is spherical in shape, and wherein the center location of the given optical tracking fiducial marker is determined by:
processing the segmented surface data to identify a plurality of surface normals associated with a surface of the given optical tracking fiducial marker;
backprojecting the surface normals beneath the surface of the given optical tracking fiducial marker; and
processing the backprojected surface normals to identify the center location.
5. The method according to claim 4 wherein processing the backprojected surface normals comprises identifying the center location based on average point of closest approach between the backprojected surface normals.
6. The method according to claim 2 wherein spectral filtering is employed to segment the surface data.
7. The method according to claim 2 wherein the surface data is manually segmented.
8. The method according to claim 1 wherein the calibration transform is generated by computing a landmark transformation.
9. The method according to claim 1 wherein the surface topology imaging device is movable relative to the optical tracking system.
10. The method according to claim 1 wherein the surface topology imaging device is rigidly fixed relative to the optical tracking system.
11. The method according to claim 1 wherein the fiducial markers reside on a surgical tool.
12. The method according to claim 1 wherein the fiducial markers are passive.
13. A surgical guidance system comprising:
an optical tracking system;
a surface topology imaging device; and
a surgical guidance controller operatively connected to the surface topology imaging device and the optical tracking system, wherein the surgical guidance controller includes a processor configured to generate a calibration transform between a first frame of reference associated with the surface topology imaging device and a second frame of reference associated with the optical tracking system by:
controlling the surface topology imaging device to scan fiducial markers residing within respective fields of view of both the surface topology imaging device and the optical tracking system, thereby obtaining surface data;
processing the surface data to locate each fiducial marker in the first frame of reference;
employing the optical tracking system to track the fiducial markers and locate each fiducial marker in the second frame of reference; and
registering the locations of the fiducial markers in the first frame of reference with the locations of the fiducial markers in the second frame of reference, thereby obtaining the calibration transform between the first frame of reference and the second frame of reference.
14. The surgical guidance system according to claim 13 wherein surgical guidance controller is configured such that processing the surface data to locate a given optical tracking fiducial marker in the first frame of reference comprises:
segmenting the surface data to obtain segmented surface data associated with the given optical tracking fiducial marker; and
processing the segmented surface data to locate the given optical tracking fiducial marker in the first frame of reference.
15. The surgical guidance system according to claim 14 wherein the surgical guidance controller is configured such that the segmented surface data associated with the given optical tracking fiducial marker is processed to determine a center location of the given optical tracking fiducial marker in the first frame of reference.
16. The surgical guidance system according to claim 15 wherein the surgical guidance controller is configured such that the center location of the given optical tracking fiducial marker is determined by:
processing the segmented surface data to identify a plurality of surface normals associated with a surface of the given optical tracking fiducial marker, modelling the given optical tracking fiducial marker as being spherical in shape;
backprojecting the surface normals beneath the surface of the given optical tracking fiducial marker; and
processing the backprojected surface normals to identify the center location.
17. The surgical guidance system according to claim 16 wherein the surgical guidance controller is configured such that processing the backprojected surface normals comprises identifying the center location based on average point of closest approach between the backprojected surface normals.
18. The surgical guidance system according to claim 14 wherein the surface topology imaging device and the surgical guidance controller are configured such that spectral filtering is employed to segment the surface data.
19. The surgical guidance system according to claim 13 wherein the surgical guidance controller is configured such that the calibration transform is generated by computing a landmark transformation.
20. The surgical guidance system according to claim 13 wherein the surface topology imaging device is movable relative to the optical tracking system.
21. The surgical guidance system according to claim 13 wherein the surface topology imaging device is rigidly fixed relative to the optical tracking system.