Methods and systems for segmentation and surface matching

• US 20070167699A1
• Filed: 12/20/2005
• Published: 07/19/2007
• Est. Priority Date: 12/20/2005
• Status: Active Grant

• Current Assignee: Elekta Ltd. (Elekta AB)
• Original Assignee: Elekta Ltd. (Elekta AB)
• Inventors: Falco, Tony, Lachaine, Martin, Lathuiliere, Fabienne, Audet, Veronique
• Granted Patent: US 8,929,621 B2
• Time in Patent Office: Days
• US Class Current: 600/407
• CPC Class Codes: G06T 2200/04 involving 3D image data
• CPC Class Codes: G06T 2207/10081 Computed x-ray tomography [CT]
• CPC Class Codes: G06T 2207/20104 Interactive definition of region of interest [ROI]
• CPC Class Codes: G06T 2207/20116 Active contour; Active surface; Snakes
• CPC Class Codes: G06T 2207/30096 Tumor; Lesion
• CPC Class Codes: G06T 7/12 Edge-based segmentation
• CPC Class Codes: G06T 7/149 involving deformable models, e.g. active contour models

Abstract

A contoured surface map of a lesion within a patient is obtained by shifting a reference surface to an estimated location in operational images. The process can be repeated to minimize errors, and the contoured surface map can then be segmented.

Claims

1. A method for obtaining a contoured surface of a lesion within a patient, the method comprising the steps of:

(a) providing a contoured reference surface of the lesion based on one or more images acquired at a first time;

(b) generating a set of operational images of the lesion at a second time;

(c) shifting the reference surface to an estimated location in the operational images;

(d) segmenting the operational images based at least in part on the shifted reference surface; and

(e) determining a contoured surface of the lesion at the second time based on the segmented images.

2. The method of claim 1 wherein the shifting comprises rotational movement.

3. The method of claim 1 wherein the shifting comprises translational movement.

4. The method of claim 1 wherein the shifting comprises scaling.

5. The method of claim 1 wherein the shifting comprises movement in three dimensions.

6. The method of claim 1 wherein the reference surface is created using one or more CT images, three-dimensional ultrasound images, two-dimensional ultrasound images, PET images and MRI images.

7. The method of claim 1 wherein the operational images are obtained using one of a CT scanner, an ultrasound device, a PET scanner and an MRI.

8. The method of claim 1 further comprising manually locating the reference surface with respect to the operational images.

9. The method of claim 1 further comprising indicating points within the operational images and mapping the points to surface elements on the reference surface to determine the shift.

10. The method of claim 9 wherein the surface elements on the reference surface comprise at least one of the group consisting of points, triangles, and lines.

11. The method of claim 9 further comprising minimizing the distance between the indicated points and mapped surface elements.

12. The method of claim 9 wherein the indicated points are in multiple planes.

13. The method of claim 9 wherein the indicated points are within one two-dimensional plane.

14. The method of claim 13 further comprising obtaining additional points from the contoured surface and repeating steps (c) through (d), substituting the shifted reference surface for the segmented operational images.

15. The method of claim 1 further comprising obtaining two-dimensional cross-sectional curves from the contoured reference surface.

16. The method of claim 15 wherein the two-dimensional cross-sectional curves are obtained from the shifted contoured reference surface.

17. The method of claim 15 wherein the two-dimensional cross-sectional curves are radially offset from each other.

18. The method of claim 15 wherein the two-dimensional cross-sectional curves are parallel to each other.

19. The method of claim 9 wherein the surface elements on the reference surface represent an edge boundary.

20. The method of claim 9 wherein weights are assigned to the surface elements on the reference surface and the weights are based at least in part on a clinical importance of an anatomical feature represented by the one or more surface elements.

21. The method of claim 20 wherein the clinical importance of the one or more surface elements is based at least in part on the proximity of an anatomical feature represented by the surface element to another anatomical structure of the patient.

22. The method of claim 9 wherein weights are assigned to one or more of the surface elements and the weights are based at least in part on a density of the one or more surface elements within an area of the segmented image.

23. The method of claim 9 wherein the mapping is determined by minimizing the mean square distance between surface elements in the reference surface and the indicated points.

24. The method of claim 1 wherein the first time is substantially proximate to a treatment planning session.

25. The method of claim 1 wherein the second time is substantially proximate to a treatment session.

26. A system for obtaining a contoured image of a lesion, the system comprising:

(a) a register for storing (i) a reference surface of the lesion based on one or more images acquired at a first time, (ii) a set of images of the lesion taken at a second time and (iii) estimated surface elements on at least one of the set of images;

(b) a mapping module for mapping surface elements on the reference surface to the estimated surface elements on at least one of the set of images; and

(c) a processor for shifting the reference surface based on the matched surface elements.

27. The system of claim 26 wherein the reference surface is based on images obtained using one of a CT scanner, a three-dimensional ultrasound device, a PET scanner and an MRI.

28. The system of claim 26 wherein the surface elements on the reference surface comprise at least one of the group consisting of points, triangles, and lines.

29. The system of claim 26 wherein the estimated surface elements on one of the set of images comprise at least one of the group consisting of points, triangles, and lines.

30. The system of claim 26 wherein the register further obtains two-dimensional cross-sectional curves from the shifted reference surface.

31. The system of claim 30 wherein the two-dimensional cross-sectional curves are radially offset from each other.

32. The system of claim 30 wherein the two-dimensional cross-sectional curves are parallel to each other.

33. The system of claim 26 wherein the mapping module and processor iteratively map surface elements on the reference surface to surface elements on the shifted reference surface.

34. The system of claim 26 further comprising a weighting module for assigning weights to the surface elements on the segmented image.

35. The system of claim 26 wherein the mapping is determined by minimizing the mean square distance between surface elements on the reference surface and the one or more estimated surface elements on one of the set of images.

36. The system of claim 26 wherein the first time is substantially proximate to a treatment planning session.

37. The system of claim 26 wherein the second time is substantially proximate to a treatment session.

38. An article of manufacture having computer-readable program portions embodied thereon for determining the changes to a lesion for the purpose of administering radiation treatment to the lesion, the article comprising computer-readable instructions for:

(a) providing a contoured surface of the lesion based on one or more images acquired at a first time as a reference surface;

(b) generating a set of images of the lesion at a second time as operational images;

(c) shifting the reference surface to an estimated location in the operational images;

(d) segmenting the operational images based at least in part on the shifted reference surface; and

(e) determining a contoured surface map of the lesion at the second time based on the segmented images.