Method and apparatus for CT image registration

• US 5,636,255 A
• Filed: 03/05/1996
• Issued: 06/03/1997
• Est. Priority Date: 03/05/1996
• Status: Expired due to Fees

• Current Assignee: iGO Technologies Inc.
• Original Assignee: Queen's University At Kingston
• Inventors: Ellis, Randy E.
• Primary Examiner(s): Tokar, Michael J.
• Assistant Examiner(s): Bruce, David Vernon
• Application Number:
  US08/610,938
• Time in Patent Office: 455 Days
• Field of Search: 378/20, 364/413.13, 364/413.14, 606/130
• US Class Current: 378/20
• CPC Class Codes: A61B 34/10 Computer-aided planning, simulation or modelling of surgical operations
• CPC Class Codes: A61B 6/583 using calibration phantoms
• CPC Class Codes: A61B 90/39 Markers, e.g. radio-opaque or breast lesions markers

Abstract

A method and system for correlating accuracy of computer tomography (CT) image resolution is described. Small radio-opaque markers having a diameter less than one slice width of a CT scan are embedded in the object, such as a bony skeletal member, to be measured, the object is then CT scanned so that the radio-opaque markers appear in at two slices of the scan. The markers are also physically located by detecting them with a sensor, such as a positioning pointer. Also described is one form of marker comprising a tantalum sphere mounted in a ceramic, preferably alumina, pin.

Claims

1. A method for deriving high accuracy correlation between data obtained by a computed tomography (CT) scan, in which an object is scanned in a plurality of CT slices, and data relating to said object obtained from other sources, comprising:

providing in said object at least one radio-opaque marker having a diameter less than one slice width of said CT scan;

detecting said radio-opaque marker in at least two said slices; and

determining a three dimensional position of said marker therefrom for comparison with said from other sources.

2. A method as claimed in claim 1 wherein said radio-opaque marker is a biocompatible metallic marker for implantation into a bone.

3. A method as claimed in claim 1 including the step of detecting a plurality of said markers with a sensor operatively coupled to a calibrating device.

4. A method as claimed in claim 1 wherein said other data is derived from at least one of (a) Roentgen stereogrammetric analysis (b) a mechanical pointing arm, (c) ultrasonic position sensor, (d) 3D optical tracking device (3) laser range sensor (f) stereoscopic camera (g) fluorscopic x-ray detector and (h) 3D magnetic position sensor.

5. A method as claimed in claim 3 wherein said calibrating device comprises an optical comparitor.

6. A method as claimed in claim 2 including surgically implanting said radio-opaque marker in a radio luscent biocompatible holder therefor, into a patient.

7. A marker for use in computed tomography (CT) scanning, comprising:

a radio-opaque marker elment;

a radio luscent holder

adapted to receive said marker element; and

means to secure said marker in said holder;

wherein said marker element has a diameter less than one CT scan slice width.

8. A marker as claimed in claim 7 wherein said radio luscent holder comprises a ceramic holder.

9. A marker as claimed in claim 8 wherein said radio luscent holder is an alumina holder.

10. A marker as claimed in claim 7 wherein said radio-opaque marker element is a sphere.

11. A marker as claimed in claim 10 wherein said sphere is a biocompatible metal.

12. A marker as claimed in claim 11 wherein said biocompatible metal is selected from the group consisting of tantalum, stainless steel, titanium alloys, and chrome-cobalt alloys.

13. A marker as claimed in claim 7 wherein said means to secure said marker element in said holder comprises a biocompatible, radio luscent adhesive material.

14. A marker as claimed in claim 7 wherein said holder comprises an elongated ceramic pin member having a longitudinal axial bore at one end thereof adapted to receive said marker element therein.

15. A system for deriving high accuracy correlation between data obtained by a CT scan, and data obtained from other sources, comprising:

(a) means for CT scanning in a plurality of slices of selected bandwith;

(b) radio opaque marker means having a diameter of less than said selected bandwidth;

(c) means for detecting said radio opaque marker in at least two said slices; and

(d) means for deriving said data obtained from other sources.

16. A system as claimed in claim 15 wherein said means for deriving said data obtained from other sources is selected from (a) Roentgen stereogrammatic analysis means (b) a mechanical pointing arm, (c) ultrasonic position sensor, (d) 3D optical tracking device, (e) laser range sensor (f) stereoscopic camera (g) fluorscopic x-ray detector and (h) 3D magnetic position sensor.

17. A system as claimed in claim 16 wherein said mechanical arm includes sensor means for detecting a plurality of said marker means, operatively coupled to a calibrating device.

18. A system as claimed in claim 17 wherein said sensor means comprises means to touch said marker means.

19. A system as claimed in claim 18 wherein said calibrating device comprises optical calibration means.