Automatic improvement of tracking data for intraoperative C-arm images in image guided surgery

Patent metadata

Field	Value
Publication number	US-9560291-B2
Application number	US-96867108-A
Country	US
Kind code	B2
Filing date	Jan 3, 2008
Priority date	Jan 4, 2007
Publication date	Jan 31, 2017
Grant date	Jan 31, 2017

Abstract

A system and method of determining a measure of accuracy of a registration mapping combining data indicative of spatial positions in a three-dimensional operating space and imaging data acquired with an imaging device located in a position and orientation in operating space is provided. A phantom is brought into a first pose, wherein the phantom is at least in partial view of the imaging device located in a second pose, the phantom comprising a marker assembly that can be imaged by the imaging device. Image data of the marker assembly of the phantom is acquired with the imaging device in the second pose. Imaged markers in the acquired image data of the marker assembly are located, and mapped markers are obtained by submitting spatial positions of the markers in the marker assembly of the phantom in the first pose to the registration mapping using the second pose as the imaging pose. A distance measure of the imaged markers and the mapped markers is determined as the measure of accuracy of the registration mapping.

First claim

What is claimed is:

1. A method using a system including a computer, a phantom, a tracking system and an imaging device, wherein a registration mapping is provided that combines data indicative of spatial positions in a three-dimensional operating space and imaging data acquired with the imaging device located in a second position and orientation in operating space referred to as an imaging pose, the method comprising:
a) orienting the imaging device with the phantom in a first position and orientation in the operating space, referred to as a first pose, wherein the phantom is at least in partial view of the imaging device located in a second pose, the phantom comprising a marker assembly having a plurality of markers that can be imaged by the imaging device, using X-ray dense and/or X-ray opaque crosses and/or symbols arranged in a predetermined pattern as marker elements on the marker assembly, and changing a characteristic of the marker elements to form the X-ray dense and/or X-ray opaque crosses and/or symbols;
b) acquiring by the imaging device image data of the marker assembly with the imaging device disposed in the second pose;
c) identifying by the computer imaged markers in the image data of the marker assembly acquired by the imaging device and determining by the computer first marker positions of the imaged markers identified by the computer;
d) determining by the computer second marker positions by applying the registration mapping to spatial positions of the plurality of markers of the marker assembly determined by the tracking system with the phantom in the first pose using the second pose as the imaging pose;
e) determining a distance measure of the first marker positions and the second marker positions, wherein the distance measure represents spatial differences between said first marker positions and said second marker positions by positive, non-zero values;
f) transforming the imaging pose used in the registration mapping to a different imaging pose, of the imaging device, using a rigid body transformation reducing the distance measure, if the distance measure is outside a predetermined threshold; and
g) determining whether two consecutive distance measures of the imaging poses approach one another up to the predetermined threshold or until a predetermined convergence criterion is met, thereby calibrating the imaging device.

2. The method according to claim 1 , wherein the registration mapping is rejected if the distance measure exceeds a predetermined threshold.

3. The method according to claim 1 , wherein bringing the phantom into the first pose includes automatically or manually bringing the phantom into the first pose.

4. The method according to claim 1 , further comprising determining the registration mapping based on markers in known positions relative to the imaging device.

5. The method according to claim 1 , further comprising acquiring anatomical image data before and/or after acquiring image data of the marker assembly of the phantom.

6. The method according to claim 1 , wherein the imaging device is an X-ray C-arm device.

7. The method according to claim 1 , further comprising acquiring a pose of at least one of the imaging device, the phantom, or an anatomical part of a patient via a reference marker in a known position and orientation relative to a respective imaging device, phantom or anatomical part via a position sensing system and/or a navigation system.

8. The method according to claim 1 , wherein changing a characteristic comprises switching the X-ray dense and/or X-ray opaque crosses and/or symbols on or off to form the X-ray dense and/or X-ray opaque crosses and/or symbols arranged in a predetermined pattern.

9. The method according to claim 8 , wherein switching the X-ray dense and/or X-ray opaque crosses and/or symbols on or off comprises dynamically switching the X-ray dense and/or X-ray opaque crosses and/or symbols on or off to form the X-ray dense and/or X-ray opaque crosses and/or symbols arranged in a predetermined pattern.

10. The method according to claim 1 , wherein determining first marker positions includes determining first marker positions of the imaged markers with sub-pixel accuracy in the image data of the marker assembly acquired by the imaging device.

11. The method according to claim 1 , wherein determining the second marker positions based on a position of the phantom includes using a medical tracking system to determine a position of the phantom.

12. A system comprising:
an imaging device located in a position and orientation in operating space and referred to as an imaging pose, said imaging device operable to acquire said imaging data;
a phantom comprising an assembly of markers that can be imaged by the imaging device, a marker assembly comprising X-ray dense and/or X-ray opaque crosses and/or symbols arranged in a predetermined pattern and configured to have a characteristic changed to form the X-ray dense and/or X-ray opaque crosses and/or symbols, wherein when the phantom is placed in a first position and orientation in operating space, referred to as a first pose, and in at least partial view of the imaging device located in a second pose, said imaging device is configured to acquire image data of the marker assembly of the phantom with the imaging device in the second pose;
a tracking system for tracking reference markers on the imaging device and/or the phantom; and
a computer system configured to
identify imaged markers in the image data of the marker assembly acquired by the imaging device and determine first marker positions of the imaged markers that have been identified,
determine second marker positions by applying a registration mapping combining data indicative of spatial positions in a three-dimensional operating space and imaging data to spatial positions of the assembly of markers in the marker assembly with the phantom in the first pose using the second pose as the imaging pose,
determine a distance measure of the first marker positions and the second marker positions, wherein the distance measure represents spatial differences between said first marker positions and said second marker positions by positive, non-zero values,
transform the imaging pose used in the registration mapping to a different imaging pose, of the imaging device, using a rigid body transformation reducing the distance measure, if the distance measure is outside a predetermined threshold, and
determine whether two consecutive distance measures of the imaging poses approach one another up to a predetermined threshold or until a predetermined convergence criterion is met, thereby calibrating the imaging device.

13. The system according to claim 12 , wherein the computer system is further configured to reject the registration mapping if the distance measure exceeds a predetermined threshold.

14. The system according to claim 12 , wherein the computer system is configured to determine the registration mapping based on markers in known positions relative to the imaging device.

15. The system according to claim 12 , wherein the imaging device is an X-ray C-arm device.

16. The system according to claim 12 , wherein the computer system is configured to acquire a pose of at least one of the imaging device, the phantom, and an anatomical part of a patient based on a reference marker in a known position and orientation relative to a respective at least one imaging device, phantom or anatomical part via a position sensing system and/or a navigation system.

17. The system according to claim 12 , wherein the X-ray dense and/or X-ray

Assignees

• Weiser Manfred
• Lachner Rainer
• Brainlab Ag

Inventors

• Weiser Manfred
• Lachner Rainer

Classifications

• A61B6/583 Primary

  using calibration phantoms · CPC title

• H04N23/30

  for generating image signals from X-rays · CPC title

• A61B2090/376

  using X-rays, e.g. fluoroscopy · CPC title

• H04N5/32 Primary

  Transforming X-rays (cameras or camera modules for generating image signals from X-rays H04N23/30; circuitry of SSIS for transforming X-rays into image signals H04N25/30) · CPC title

• A61B2090/364

  Correlation of different images or relation of image positions in respect to the body · CPC title