Device and method for ensuring the accuracy of a tracking device in a volume

• US 20060122497A1
• Filed: 11/14/2005
• Published: 06/08/2006
• Est. Priority Date: 11/12/2004
• Status: Active Grant

• Current Assignee: Philips Electronics Limited (Koninklijke Philips N.V.)
• Original Assignee: Philips Electronics Limited (Koninklijke Philips N.V.)
• Inventors: Glossop, Neil David
• Granted Patent: US 7,805,269 B2
• Time in Patent Office: Days
• US Class Current: 600/424
• CPC Class Codes: A61B 2017/00725 Calibration or performance testing
• CPC Class Codes: A61B 2034/2051 Electromagnetic tracking systems
• CPC Class Codes: A61B 2090/3983 Reference marker arrangements for use with image guided surgery
• 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 90/36 Image-producing devices or illumination devices not otherwise provided for
• CPC Class Codes: B33Y 80/00 Products made by additive manufacturing

Abstract

The invention provides a system and method for testing and correcting the accuracy of a tracking device in a volume using an accuracy device, wherein the accuracy device includes a rigid object and one or more position indicating elements within or upon the rigid object, wherein baseline position information regarding position indicating elements relative to a frame of reference of the rigid object is known. The invention may also include placing the rigid object into an experimental volume and sampling position and orientation information regarding the one or more position indicating elements relative to a frame of reference of the tracking device. The position and orientation information may then be compared to the baseline position and orientation information. If a difference between the experimental position and orientation information and the baseline position and orientation information exceeds a predetermined threshold, a correction map enabling adjustment of the tracking device to correct for the distortion in the experimental volume may be generated, and the tracking device may be adjusted accordingly.

Claims

1. A method for testing and correcting the accuracy of a magnetic tracking device in a volume using an accuracy device, wherein the accuracy device includes a rigid object and one or more position indicating elements placed at one or more known points within or upon the rigid object, wherein baseline position and orientation information regarding the one or more known points relative to a frame of reference of the rigid object is known, the method comprising:

placing the rigid object into a volume;

obtaining sampled position and orientation information of the one or more position indicating elements relative to a frame of reference of the tracking device in the volume; and

comparing the sampled position and orientation information to the baseline position and orientation information.

2. The method of claim 1, wherein the volume comprises an undistorted volume and the sampled position and orientation information comprises measured position and orientation information.

3. The method of claim 1, wherein the volume comprises an experimental volume and the sampled position and orientation information comprises experimental position and orientation information, the method further comprising:

characterizing a distortion in the experimental volume if a difference between the experimental position and orientation information and the baseline position and orientation information exceeds a predetermined threshold;

creating a correction map that enables adjustment of the tracking device to correct for the distortion in the experimental volume; and

adjusting the tracking device according to the correction map.

4. The method of claim 1, wherein obtaining sampled position and orientation information of the one or more position indicating elements further comprises registering the sampled position and orientation information to the frame of reference of the rigid object.

5. The method of claim 3, further comprising:

conducting a medical procedure on a patient in the experimental volume while the rigid object is in the experimental volume; and

monitoring the experimental volume for distortions by periodically obtaining additional experimental position and orientation information and comparing the additional experimental position and orientation information to the baseline position and orientation information.

6. The method of claim 3, further comprising:

conducting a medical procedure on a patient in the experimental volume while the rigid object is in the experimental volume; and

dynamically referencing a portion of the patient using the one or more position indicating elements.

7. The method of claim 6, wherein the dynamic reference is the rigid object.

8. The method of claim 1, wherein each of the one or more position indicating elements are connected to a multiplexer, and wherein the sampled position and orientation information is obtained by the tracking device via cycling through the one or more position indicating elements using the multiplexer.

9. A method for testing and correcting the accuracy of a magnetic tracking device in a volume using an accuracy device, wherein the accuracy device includes a rigid object having one or more passageways embedded therein and one or more position indicating elements, wherein baseline position and orientation information regarding the one or more passageways relative to a frame of reference of the rigid object is known, the method comprising:

placing the rigid object into a volume;

obtaining sample position and orientation information regarding the one or more passageways relative to a frame of reference of the tracking device in the volume by sampling position and orientation information regarding the one or more position indicating elements as the position indicating elements are placed into or continually moved within the one or more passageways;

registering the sampled position and orientation information to the frame of reference of the rigid object; and

comparing the sampled position and orientation information to the baseline position and orientation information.

10. The method of claim 9, wherein the volume comprises an experimental volume and the sampled position and orientation information comprises experimental position and orientation information, the method further comprising:

characterizing a distortion in the experimental volume if a difference between the experimental position and orientation information and the baseline position and orientation information exceeds a predetermined threshold;

creating a correction map that enables adjustment of the tracking device to correct for the distortion in the experimental volume; and

adjusting the tracking device according to the correction map.

11. A system for testing and correcting the accuracy of a magnetic tracking device in a volume, comprising:

a magnetic tracking device that tracks a position and orientation for each of one or more position indicating elements relative to a frame of reference of the tracking device;

a rigid object that includes a plurality of known points, wherein for each of the plurality of known points, baseline position and orientation information is known relative to a frame of reference of the rigid object, wherein the rigid object is placed into a volume and the one or more position indicating elements are positioned at one or more of the plurality of points to produce sampled position and orientation information regarding one or more of the position indicating elements in the frame of reference of the tracking device.

12. The system of claim 11, further comprising means for comparing the baseline position and orientation information of one or more of the plurality of points to the sampled position and orientation information of one or more of the position indicating elements.

13. The system of claim 11, wherein the volume comprises a surgical environment and further comprising means for calculating a correction map characterizing any distortions in the surgical environment and means for applying the correction map to the tracking device.

14. The system of claim 11, further comprising means for registering the sampled position and orientation information to the frame of reference of the rigid object.

15. The system of claim 11, wherein the sampled position and orientation information is obtained by sampling position and orientation information of one or more of the position indicating elements as the one or more position indicating elements are moved or placed within predefined passageways within the rigid object.

16. The system of claim 15, wherein the predefined passageways are made using a rapid prototyping process chosen from one of selective laser sintering (SLS), stereolithography (SLA), or 3D printing.

17. The system of claim 12, further comprising a multiplexer connected to the one or more position indicating elements, wherein the sampled position and orientation information is obtained by cycling through the one or more position indicating elements using the multiplexer.

18. A method for testing and correcting the accuracy of a magnetic tracking device in a volume using an accuracy device, wherein the accuracy device includes a rigid object and one or more position indicating elements placed at one or more known points within or upon the rigid object, wherein baseline position information regarding the one or more known points relative to a frame of reference of the rigid object is known, the method comprising:

placing the rigid object into a known undistorted volume;

obtaining measured position information of the one or more position indicating elements relative to a frame of reference of the tracking device in the known undistorted volume;

registering the measured position information to the frame of reference of the rigid object;

comparing the measured position information to the baseline position information;

placing the rigid object into an experimental volume if a difference between the measured position information and the baseline position information does not exceed a predetermined threshold;

obtaining experimental position information of the one or more position indicating elements relative to a frame of reference of the tracking device in the experimental volume;

registering the experimental position information to the frame of reference of the rigid object;

comparing the experimental position information to the baseline position information;

characterizing a distortion in the experimental volume if a difference between the experimental position information and the baseline position information exceeds a predetermined threshold;

creating correction map that enables adjustment of the tracking device to correct for the distortion in the experimental volume; and

adjusting the tracking device according to the correction map.