MARKER-FREE TRACKING REGISTRATION AND CALIBRATION FOR EM-TRACKED ENDOSCOPIC SYSTEM

• US 20120069167A1
• Filed: 04/02/2010
• Published: 03/22/2012
• Est. Priority Date: 05/18/2009
• Status: Abandoned Application

• Current Assignee: Koninklijke Philips Electronics N.V. (Koninklijke Philips N.V.)
• Original Assignee: Koninklijke Philips Electronics N.V. (Koninklijke Philips N.V.)
• Inventors: Liu, Xin, Gutierrez, Luis Felipe
• Application Number:
  US13/320,910
• Publication Number:
  US 20120069167A1
• Time in Patent Office: Days
• US Class Current: 348/65
• CPC Class Codes: A61B 6/584 determining position of components of the apparatus or device using images of the phantom
• CPC Class Codes: G06T 2207/10068 Endoscopic image
• CPC Class Codes: G06T 2207/10072 Tomographic images
• CPC Class Codes: G06T 7/32 using correlation-based methods
• CPC Class Codes: G06T 7/33 using feature-based methods
• CPC Class Codes: G06T 7/38 Registration of image sequences

Abstract

A system and method for image-based registration between images locating (304) a feature in a pre-operative image and comparing (307) real-time images taken with a tracked scope with the pre-operative image taken of the feature to find a real-time image that closely matches the pre-operative image. A closest match real-time image is registered (308) to the pre-operative image to determine a transformation matrix between a position of the pre-operative image and a position of the real-time image provided by a tracker such that the transformation matrix permits tracking real-time image coordinates using the tracker in pre-operative image space.

Claims

1. A method for image-based registration between images, comprising:

locating (304) a feature in a pre-operative image;

comparing (307) real-time images taken with a tracked scope with the pre-operative image taken of the feature to find a real-time image that closely matches the pre-operative image; and

registering (308) a closest match real-time image to the pre-operative image to determine a transformation matrix between a position of the pre-operative image and a position of the real-time image provided by a tracker such that the transformation matrix permits tracking real-time image coordinates using the tracker in pre-operative image space.

2. The method as recited in claim 1, wherein the real-time images are collected using an endoscope camera (45) with electromagnetic tracking.

3. The method as recited in claim 2, further comprising progressing the endoscope camera (45) other than along a middle line of a passage being observed.

4. The method as recited in claim 1, wherein comparing includes optimizing (18) a maximum similarity between the real images and the pre-operative image.

5. The method as recited in claim 1, wherein the transformation matrix is determined to align the pre-operative image space with electromagnetic tracking space during an endoscopic procedure.

6. The method as recited in claim 1, further comprising initially calibrating an endoscopic camera to a tracking device.

7. The method as recited in claim 1, further comprising determining a virtual camera pose for the pre-operative image and correlating the pre-operative pose with a real camera pose of the closest matched real image to determine the transformation matrix.

8. A system for image-based registration between images, comprising:

an endoscope (406) including a camera (408) for collecting real-time images during a procedure, the endoscope including a tracker (410) for locating a tip of the endoscope; and

a computer implemented program (412) stored in memory media configured to compare a set of real-time images taken by the camera with a pre-operative image for a same subject to find a closest match between the real-time images and the pre-operative image, the program being configured to determine a transformation matrix (420) to enable endoscopic tracking using pre-operative image space free from the use of contact markers.

9. The system as recited in claim 8, wherein endoscope progression is tracked other than along a middle line of a passage being observed.

10. The system as recited in claim 8, wherein the program (412) further includes an optimization feature (422) configured to find a maximum similarity to determine the closest match between images.

11. The system as recited in claim 8, wherein the transformation matrix (420) is employed to register coordinates of pre-operative images to electromagnetic tracking coordinates during an endoscopic procedure.

12. The system as recited in claim 8, further comprising a display (456) configured to show endoscope progression in pre-operative image space.

13. A method for camera position calibration for guided endoscopy, comprising:

collecting (350) pre-operative images of a subject having markers;

touching (352) each of the markers using a tracker to register the pre-operative image and a camera images associated with the tracker;

determining (354) a preoperative image associated with an endoscope location at a first position as determined by the tracker;

adjusting (356) the endoscope until an image obtained by the camera matches with the pre-operative image at a second position as determined by the tracker; and

determining (358) a rotation and translation matrix between the first and second positions to calibrate the tracker to the camera.

14. The method as recited in claim 13, wherein the marker includes fiducial markers (122) and touching each of the markers using the tracker includes fiducial-based registration.

15. The method as recited in claim 13, wherein adjusting (356) the scope is performed by an adjustment of the operator.

16. The method as recited in claim 13, wherein determining (358) a rotation and translation matrix is employed to calibrate coordinates of the camera to the tracker images such that the calibration and registration with pre-operative images permits updating the pre-operative images together with real-time images taken by the camera.

17. The method as recited in claim 13, wherein the camera calibration is performed on-line during a procedure.

18. A system for camera position calibration for guided endoscopy, comprising:

an endoscope (108) including a camera (130) for collecting real-time images during a procedure, the endoscope including a tracker (104) for locating a tip of the endoscope;

pre-operative images collected using markers (122), the pre-operative images having coordinates registered with coordinates of the tracker by touching each of the markers using the tracker; and

a rotation and translation matrix (113) stored in memory and derived by a motion of adjusting the endoscope from a first position to a second position where the first position includes a first camera pose and the second position includes a second camera pose which better matches a reference pre-operative image such that the matrix provides calibration between the tracker and the camera.

19. The system as recited in claim 18, wherein the markers (122) include fiducial markers and touching each of the markers using a tracker includes fiducial-based registration.

20. The system as recited in claim 18, wherein the endoscope (108) is adjusted by an adjustment of an operator.

21. The system as recited in claim 18, wherein a camera coordinate system is transformed to the tracker coordinate system using the matrix (113).