C-arm calibration method for 3D reconstruction in an imaging system

• US 5,963,613 A
• Filed: 12/31/1997
• Issued: 10/05/1999
• Est. Priority Date: 12/31/1997
• Status: Expired due to Term

• Current Assignee: Siemens Medical Solutions USA Incorporated (Siemens AG)
• Original Assignee: Siemens Corporate Research Incorporated (Siemens AG)
• Inventors: Navab, Nassir
• Primary Examiner(s): Bruce, David Vernon
• Application Number:
  US09/001,505
• Time in Patent Office: 643 Days
• Field of Search: 378/4, 378/15, 378/901
• US Class Current: 378/4
• CPC Class Codes: A61B 2017/22034 for gripping the obstruction or the tissue part from inside
• CPC Class Codes: A61B 2090/367 creating a 3D dataset from 2D images using position information
• 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 6/12 Arrangements for detecting or locating foreign bodies
• CPC Class Codes: A61B 6/4441 the rigid structure being a C-arm or U-arm
• CPC Class Codes: A61B 6/583 using calibration phantoms
• CPC Class Codes: G06T 11/005 Specific pre-processing for tomographic reconstruction, e.g. calibration, source positioning, rebinning, scatter correction, retrospective gating
• CPC Class Codes: Y10S 378/901 Computer tomography program or processor

Abstract

A C-arm calibration method for 3D reconstruction in an imaging system comprising an imaging source and an imaging plane, utilizes a planar transformation for relating voxels in a voxel space and pixels in the imaging plane, and comprises the steps of defining a source coordinate system in reference to the imaging source; defining first and second normal planes in the voxel space, the planes being parallel to one another, neither including the origin of the source coordinate system and being substantially normal to an optical axis from the source to the imaging plane; defining a relationship between the source coordinate system and another coordinate system, herein referred to as a world coordinate system, by a rotation parameter, identifying pixel location coordinates for a respective pixel corresponding to each voxel in each of the first and second normal planes by utilizing the rotation parameter, storing a value of a filtered image at the respective pixel location; and accumulating contributions corresponding to a plurality of image projections so as to thereby reconstruct the each voxel on each of the first and second normal planes.

Claims

1. A C-arm calibration method for 3D reconstruction in an imaging system comprising an imaging source and an imaging plane, said method utilizing a planar transformation for relating voxels in a voxel space and pixels in said imaging plane, and comprising the steps of:

defining a source coordinate system in reference to said imaging source;

defining first and second normal planes in said voxel space, said planes being parallel to one another, neither including the origin of said source coordinate system and being substantially normal to an optical axis from said source to said imaging plane;

defining a relationship between said source coordinate system and another coordinate system, herein referred to as a world coordinate system, by a rotation parameter;

identifying pixel location coordinates for a respective pixel corresponding to each voxel in each of said first and second normal planes by utilizing said rotation parameter;

storing a value of a filtered image at said respective pixel location; and

accumulating contributions corresponding to a plurality of image projections so as to thereby reconstruct said each voxel on each of said first and second normal planes.

2. A C-arm calibration method in accordance with claim 1, including a step of forming said plurality of image projections as a succession of images as by rotation of an imaging C-arm.

3. A C-arm calibration method in accordance with claim 1, including a step of performing a calibration step for determining values for said transformation parameters.

4. A C-arm calibration method for 3D reconstruction in an imaging system comprising an imaging source and an imaging plane, said method utilizing a planar transformation for relating voxels in a voxel space and pixels in said imaging plane, and comprising the steps of:

defining a source coordinate system in reference to said imaging source;

defining first and second normal planes in said voxel space, said planes being parallel to one another, neither including the origin of said source coordinate system and being substantially normal to an optical axis from said source to said imaging plane;

defining a relationship between said source coordinate system and another coordinate system, herein referred to as a world coordinate system, by a rotation parameter;

identifying pixel location coordinates for a respective pixel corresponding to each voxel in each of said first and second normal planes by utilizing said rotation parameter;

storing a value of a filtered image at said respective pixel location; and

accumulating contributions corresponding to a plurality of image projections so as to thereby reconstruct said each voxel on each of said first and second normal planes.

dividing said voxel space into a plurality of planes parallel to said normal planes;

back projecting an image of a plurality of pixels on said image plane onto a set of coplanar voxels defining one of said plurality of parallel planes; and

defining a relationship in said source coordinate system between each of said plurality of pixels and corresponding ones of said coplanar voxels so as to obtain a 2-dimensional mapping between points on said one of said plurality of parallel planes and pixels on said image plane.

5. A C-arm calibration method in accordance with claim 4, wherein said plurality of pixels on said image plane comprises at least 4 pixels.

6. A C-arm calibration method in accordance with claim 5, including a step of imaging 2 further voxels outside of said one of said plurality of parallel planes, whereby coordinate information is obtained defining a position for said source in terms of said 2-dimensional mapping.

7. A C-arm calibration method in accordance with claim 5 including a step of deriving values for said transformation parameters from said coordinate information.

8. A C-arm calibration method in accordance with claim 5 including a step of utilizing said 2-dimensional mapping to backproject onto said one of said plurality of said planes an image formed of pixels on said imaging plane.

9. A C-arm calibration method in accordance with claim 5 including a step of utilizing scaling information between planes of said plurality of planes and said 2-dimensional mapping to backproject onto another of said plurality of planes, other than said one, an image formed of pixels on said imaging plane.

10. Apparatus for C-arm calibration for 3D reconstruction in an imaging system comprising an imaging source and an imaging plane, said apparatus utilizing a planar transformation for relating voxels in a voxel space and pixels in said imaging plane, and comprising.

means for storing a defined a source coordinate system in reference to said imaging source;

means for storing first and second normal planes in said voxel space, said planes being parallel to one another, neither including the origin of said source coordinate system and being substantially normal to an optical axis from said source to said imaging plane;

means for storing a defined relationship between said source coordinate system and another coordinate system, herein referred to as a world coordinate system, by a rotation parameter;

data processing means for identifying and storing pixel location coordinates for a respective pixel corresponding to each voxel in each of said first and second normal planes by utilizing said rotation parameter,

means for storing a value of a filtered image at said respective pixel location; and

data processing means for accumulating contributions corresponding to a plurality of image projections so as to thereby reconstruct said each voxel on each of said first and second normal planes.

11. Apparatus for C-arm calibration in accordance with claim 10, including data processing means for forming said plurality of image projections as a succession of images as by rotation of an imaging C-arm.

12. Apparatus for C-arm calibration in accordance with claim 10, including data processing means for performing a calibration step for determining values for said transformation parameters.

13. Apparatus for C-arm calibration for 3D reconstruction in an imaging system comprising an imaging source and an imaging plane, said apparatus utilizing a planar transformation for relating voxels in a voxel space and pixels in said imaging plane, and comprising:

means for storing a defined source coordinate system in reference to said imaging source;

means for storing defined first and second normal planes in said voxel space, said planes being parallel to one another, neither including the origin of said source coordinate system and being substantially normal to an optical axis from said source to said imaging plane;

means for storing a defined a relationship between said source coordinate system and another coordinate system, herein referred to as a world coordinate system, by a rotation parameter;

data processing means for identifying and storing pixel location coordinates for a respective pixel corresponding to each voxel in each of said first and second normal planes by utilizing said rotation parameter;

means for storing a value of a filtered image at said respective pixel location; and

data processing means for accumulating and storing contributions corresponding to a plurality of image projections so as to thereby reconstruct said each voxel on each of said first and second normal planes.

data processing means for dividing said voxel space into a plurality of planes parallel to said normal planes;

data processing means for back projecting an image of a plurality of pixels on said image plane onto a set of coplanar voxels defining one of said plurality of parallel planes; and

data processing means for defining a relationship in said source coordinate system between each of said plurality of pixels and corresponding ones of said coplanar voxels so as to obtain a 2-dimensional mapping between points on said one of said plurality of parallel planes and pixels on said image plane.

14. Apparatus for C-arm calibration in accordance with claim 13, wherein said plurality of pixels on said image plane comprises at least 4 pixels.

15. Apparatus for C-arm calibration in accordance with claim 13, including data processing means for imaging 2 further voxels outside of said one of said plurality of parallel planes, whereby coordinate information is obtained defining a position for said source in terms of said 2-dimensional mapping.

16. Apparatus for C-arm calibration in accordance with claim 13 including data processing means for deriving values for said transformation parameters from said coordinate information.

17. Apparatus for C-arm calibration in accordance with claim 13 including data processing means for utilizing said 2-dimensional mapping to backproject onto said one of said plurality, of said planes an image formed of pixels on said imaging plane.

18. Apparatus for C-arm calibration in accordance with claim 13 including data processing means for utilizing scaling information between planes of said plurality of planes and said 2-dimensional mapping to backproject onto another of said plurality of planes, other than said one, an image formed of pixels on said imaging plane.