Method and apparatus for correction of errors in surfaces

• US 8,867,806 B2
• Filed: 08/01/2011
• Issued: 10/21/2014
• Est. Priority Date: 08/01/2011
• Status: Active Grant

• Current Assignee: IMPAC Medical Systems, Inc. (Elekta AB)
• Original Assignee: IMPAC Medical Systems, Inc. (Elekta AB)
• Inventors: Hibbard, Lyndon S.
• Primary Examiner(s): CHANG, JON CARLTON
• Application Number:
  US13/195,771
• Publication Number:
  US 20130034276A1
• Time in Patent Office: 1,177 Days
• Field of Search: None
• US Class Current: 382/128
• CPC Class Codes: G06T 17/30 Polynomial surface description
• CPC Class Codes: G06T 19/20 Editing of 3D images, e.g. changing shapes or colours, aligning objects or positioning parts
• CPC Class Codes: G06T 2210/41 Medical
• CPC Class Codes: G06T 2219/2021 Shape modification

Abstract

Methods and systems are disclosed for correcting segmentation errors in pre-existing contours and surfaces. Techniques are disclosed for receiving one or more edit contours from a user, identifying pre-existing data points that should be eliminated, and generating a new corrected surface. Embodiments disclosed herein relate to using received edit contours to generate a set of points on a pre-existing surface, and applying a proximity test to eliminate pre-existing constraint points that are undesirable.

Claims

1. A computer-implemented method for processing image data of an anatomical object utilizing a processor executing computer-executable instructions, the method comprising:

receiving a first plurality of data points defining a three-dimensional surface reflecting a first contour and representing at least a portion of the anatomical object;

receiving a second plurality of data points defining at least one edit contour for modifying the three-dimensional surface;

generating a third plurality of data points based on the first and second plurality of data points, the third plurality of data points lying on the three-dimensional surface; and

identifying at least a subset of the first plurality of data points for elimination by applying a proximity threshold based on proximity between each of the first plurality of data points and at least one of the third plurality of data points,

wherein the identified subset defines a modification of at least a portion of the three-dimensional surface.

2. The computer-implemented method of claim 1, further comprising:

generating a fourth plurality of data points based on the first, second, and third plurality of data points, the fourth plurality of data points comprising the second plurality of data points, and the first plurality of data points excluding the identified subset of the first plurality of data points.

3. The computer-implemented method of claim 2, further comprising:

generating a corrected surface based on the fourth plurality of data points; and

displaying the corrected surface on a display device.

4. The computer-implemented method of claim 1, wherein the identifying step further comprises:

generating the third plurality of data points by projecting on the three-dimensional surface the second plurality of data points,

evaluating each data point in the first plurality of data points for its proximity to the third plurality of data points, and

identifying data points from the first plurality of data points based on a determination that the data point is within a pre-determined threshold distance from at least one of the third plurality of data points.

5. The computer-implemented method of claim 1, wherein the identifying step further comprises:

generating a surface patch based on the first and second plurality of data points, the surface patch comprising a plurality of vertices on the three-dimensional surface, the surface patch area being bounded by the end points of the at least one edit contour,

evaluating each data point in the first plurality of data points for its proximity to the plurality of vertices, and

identifying data points from the first plurality of data points for elimination based on a determination that the data point is within a pre-determined threshold distance from at least one of the vertices.

6. The computer-implemented method of claim 1, wherein the at least one edit contour corrects at least one of an over-segmentation error or an under-segmentation error for the object of interest.

7. The computer-implemented method of claim 1, wherein the at least one edit contour comprises a first edit contour in a first plane, and a second edit contour in a second plane.

8. The computer-implemented method of claim 7, wherein the at least one edit contour further comprises a third edit contour in a third plane.

9. The computer-implemented method of claim 1, wherein the anatomical object comprises at least one of a bladder or a prostate.

10. The computer-implemented method of claim 1, wherein the step of applying the proximity threshold comprises computing a value based on a function of a distance between two points and comparing the computed value to a threshold.

11. The computer-implemented method of claim 10, wherein the function comprises the distance squared or a logarithm of the distance.

12. An apparatus for processing image data of an anatomical object, the apparatus comprising:

a processor configured to;

receive a first plurality of data points defining a three-dimensional surface reflecting a first contour and representing at least a portion of the anatomical object;

receive a second plurality of data points defining at least one edit contour for modifying the three-dimensional surface;

generate a third plurality of data points based on the first and second plurality of data points, the third plurality of data points lying on the three-dimensional surface; and

identify at least a subset of the first plurality of data points for elimination by applying a proximity threshold based on proximity between each of the first plurality of data points and at least one of the third plurality of data points, wherein the identified subset defines a modification of at least a portion of the three-dimensional surface.

13. The apparatus of claim 12, wherein the processor is further configured to generate a fourth plurality of data points based on the first, second, and third plurality of data points, the fourth plurality of data points comprising the second plurality of data points plus the first plurality of data points excluding the identified data points.

14. The apparatus of claim 13, wherein the processor is further configured to:

generate a corrected surface based on the fourth plurality of data points; and

display the corrected surface on a display device.

15. The apparatus of claim 12, wherein the processor is further configured to:

generate the third plurality of data points by projecting on the three-dimensional surface the second plurality of data points;

evaluate each data point in the first plurality of data points for its proximity to the third plurality of data points; and

identify data points from the first plurality of data points for elimination based on a determination that the data point is within a pre-determined threshold distance from at least one of the third plurality of data points.

16. The apparatus of claim 12, wherein the processor is further configured to:

generate a surface patch based on the first and second plurality of data points, the surface patch comprising a plurality of vertices on the three-dimensional surface, the surface patch area being bounded by the end points of the at least one edit contour;

evaluate each data point in the first plurality of data points for its proximity to the plurality of vertices; and

identify data points from the first plurality of data points for elimination based on a determination that the data point is within a pre-determined threshold distance from at least one of the vertices.

17. The apparatus of claim 12, wherein the at least one edit contour corrects at least one of an over-segmentation error or an under-segmentation error for the object of interest.

18. The apparatus of claim 12, wherein the at least one edit contour comprises a first edit contour in a first plane, and a second edit contour in a second plane.

19. The apparatus of claim 18, wherein the at least one edit contour further comprises a third edit contour in a third plane.

20. The apparatus of claim 12, wherein the anatomical object comprises at least one of a bladder or a prostate.

21. The apparatus of claim 12, wherein the processor is configured to apply the proximity threshold by first computing a value based on a function of distance between two points and then comparing the computed value to a threshold.

22. The apparatus of claim 21, wherein the function of distance comprises at least one of a distance squared or a logarithm of the distance.

23. A computer program product for processing image data of an anatomical object, comprising:

a non-transitory computer-readable medium for storing a plurality of instructions that are executable by a processor to;

receive a first plurality of data points defining a three-dimensional surface reflecting a first contour and representing at least a portion of the anatomical object;

receive a second plurality of data points defining at least one edit contour for modifying the three-dimensional surface;

generate a third plurality of data points based on the first and second plurality of data points, the third plurality of data points lying on the three-dimensional surface; and

identify at least a subset of the first plurality of data points for elimination by applying a proximity threshold based on proximity between each of the first plurality of data points and at least one of the third plurality of data points, wherein the identified subset defines a modification of at least a portion of the three-dimensional surface.