SYSTEM AND METHOD FOR IN-CONTEXT VOLUME VISUALIZATION USING VIRTUAL INCISION

Abstract

A method for volume rendering a digitized medical image includes providing a digitized medical image volume comprising a plurality of intensities on a 3-dimensional grid of points, providing a projection plane comprising a 2-dimensional lattice of points onto which rendering rays are projected from a viewing point through said image volume, advancing a sampling point along a ray through said image volume, generating an incision region within said image volume, determining whether said sampling point is within said incision region, wherein a first transfer function is applied to a sample value interpolated from a first volume if said sampling point is within the incision region, and a second transfer function is applied to a sample value interpolated from a second volume if said sampling point is outside the incision region, and accumulating the output of the transfer function.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1( a)-(b) illustrate metaphors for a virtual incision method according to an embodiment of the invention.

FIG. 2 depicts a virtually opened head in a CT image, according to an embodiment of the invention.

FIGS. 3( a)-(d) show direct volume renderings of an abdomen CT data set with procedural opening of the data set using a virtual incision plane, according to an embodiment of the invention.

FIGS. 4( a)-(d) show further direct volume renderings of an abdomen CT data set with procedural opening of the data set using a virtual incision plane, according to an embodiment of the invention.

FIGS. 5( a)-(b) show renderings of curved multi-planar reconstructions (MPRs) on the boundary of the virtual incision, according to an embodiment of the invention.

FIG. 6 is a flowchart of a virtual incision method for in-context volume visualization, according to an embodiment of the invention.

FIG. 7 is a block diagram of an exemplary computer system for implementing a virtual incision method for in-context volume visualization, according to an embodiment of the invention.

Claims

1. A method of volume rendering a digitized medical image comprising the steps of: providing a digitized medical image volume, said image comprising a plurality of intensities on a 3-dimensional grid of points;providing a projection plane comprising a 2-dimensional lattice of points onto which rendering rays are projected from a viewing point through said image volume;advancing a sampling point along a ray through said image volume;generating an incision region within said image volume;determining whether said sampling point is within said incision region, wherein a first transfer function is applied to a sample value interpolated from a first volume if said sampling point is within the incision region, and a second transfer function is applied to a sample value interpolated from a second volume if said sampling point is outside the incision region; andaccumulating the output of the transfer function.

2. The method of claim 1, wherein said incision region is a plane of finite thickness parallel to the ray direction, and determining whether said sampling point is within the incision region comprises evaluating a product of the position of the sampling point with an equation representing the incision plane.

3. The method of claim 1, wherein said incision region is a sphere of finite radius within said image volume, and determining whether said sampling point is within the incision region comprises evaluating a distance of the position of the sampling point to the center point of the sphere.

4. The method of claim 1, wherein said first volume and said second volume are the same.

5. The method of claim 1, further comprising determining whether said sampling point is on a boundary of said incision region.

6. The method of claim 5, further comprising applying a third transfer function to a sample value interpolated from a volume about said sampling point, if said sampling point is sufficiently close to said boundary.

7. The method of claim 5, further comprising interpolating an output on the boundary of said incision region from the output of said first transfer function and the output of the second transfer function.

8. The method of claim 1, wherein the output of the first transfer function either discards or makes the intensities of the first volume transparent with respect to the intensities of the second volume.

9. The method of claim 1, wherein the first transfer function deforms the volume about the sampling point {right arrow over (x)} according to the transformation

10. The method of claim 5, further comprising performing a curved MPR visualization at said incision boundary.

11. The method of claim 10, further comprising changing a viewing distance for said curved MPR visualization between rendering frames.

12. The method of claim 1, further comprising changing parameters characterizing said incision region during rendering, wherein said parameters include position and orientation of said incision region with respect to the viewing point, and the shape and size of said incision region.

13. A method of volume rendering a digitized medical image comprising the steps of: providing a digitized medical image volume, said image comprising a plurality of intensities on a 3-dimensional grid of points;projecting a ray from a viewing point through said image volume onto a 2-dimensional projection plane wherein a sampling point is advanced along said ray;generating an incision region within said image volume by providing parameters characterizing said incision region, wherein said parameters include position and orientation of said incision region with respect to the viewing point, and a shape and size of said incision region; andcalculating a distance from said sampling point to a boundary of said incision region.

14. The method of claim 13, further comprising using said distance to determine which of a plurality of sub-volumes contains said sampling point, wherein each of said plurality of sub-volumes is associated with a transfer function, and applying the transfer function associated with the sub-volume containing said sampling point to a sample value interpolated from said sub-volume; and accumulating the output of the transfer function along said ray.

15. The method of claim 14, further comprising interpolating the output of the plurality of transfer functions between said sub-volumes.

16. A program storage device readable by a computer, tangibly embodying a program of instructions executable by the computer to perform the method steps for volume rendering a digitized medical image, the method comprising the steps of: providing a digitized medical image volume, said image comprising a plurality of intensities on a 3-dimensional grid of points;providing a projection plane comprising a 2-dimensional lattice of points onto which rendering rays are projected from a viewing point through said image volume;advancing a sampling point along a ray through said image volume;generating an incision region within said image volume;determining whether said sampling point is within said incision region, wherein a first transfer function is applied to a sample value interpolated from a first volume if said sampling point is within the incision region, and a second transfer function is applied to a sample value interpolated from a second volume if said sampling point is outside the incision region; andaccumulating the output of the transfer function.

17. The computer readable program storage device of claim 16, wherein said incision region is a plane of finite thickness parallel to the ray direction, and determining whether said sampling point is within the incision region comprises evaluating a product of the position of the sampling point with an equation representing the incision plane.

18. The computer readable program storage device of claim 16, wherein said incision region is a sphere of finite radius within said image volume, and determining whether said sampling point is within the incision region comprises evaluating a distance of the position of the sampling point to the center point of the sphere.

19. The computer readable program storage device of claim 16, wherein said first volume and said second volume are the same.

20. The computer readable program storage device of claim 16, the method further comprising determining whether said sampling point is on a boundary of said incision region.

21. The computer readable program storage device of claim 20, the method further comprising applying a third transfer function to a sample value interpolated from a volume about said sampling point, if said sampling point is sufficiently close to said boundary.

22. The computer readable program storage device of claim 20, the method further comprising interpolating an output on the boundary of said incision region from the output of said first transfer function and the output of the second transfer function.

23. The computer readable program storage device of claim 16, wherein the output of the first transfer function either discards or makes the intensities of the first volume transparent with respect to the intensities of the second volume.

24. The computer readable program storage device of claim 16, wherein the first transfer function deforms the volume about the sampling point {right arrow over (x)} according to the transformation

25. The computer readable program storage device of claim 20, the method further comprising performing a curved MPR visualization at said incision boundary.

26. The computer readable program storage device of claim 25, the method further comprising changing a viewing distance for said curved MPR visualization between rendering frames.

27. The computer readable program storage device of claim 16, the method further comprising changing parameters characterizing said incision region during rendering, wherein said parameters include position and orientation of said incision region with respect to the viewing point, and the shape and size of said incision region.