Methods and systems for segmentation and surface matching

• US 8,929,621 B2
• Filed: 12/20/2005
• Issued: 01/06/2015
• 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, Lathuilire, Fabienne, Audet, Vronique
• Primary Examiner(s): Allison, Andrae S
• Application Number:
  US11/313,236
• Publication Number:
  US 20070167699A1
• Time in Patent Office: 3,304 Days
• Field of Search: 382128-134, 382/164, 382/171, 382/173, 600/443, 600/516, 600/587, 600/337, 600/344, 600/138, 600/139, 600/159, 600/190, 600/197, 600/209
• US Class Current: 382/128
• 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 of obtaining a contoured surface representation of a lesion within a patient, the method comprising:

obtaining a first contour representing an outer surface of the lesion at a first time prior to treatment, the first contour having been obtained from one or more planning images of the lesion acquired at the first time, the first contour including a first set of surface elements;

obtaining a set of treatment images of the lesion, the treatment images having been acquired from the patient during a treatment session at a second time later than the first time, wherein the treatment images include a second set of surface elements corresponding to the lesion during the treatment session at the second time;

positioning the first contour from the planning images within the set of treatment images at a location corresponding to the lesion;

calculating a mapping between the first set of surface elements and the second set of surface elements;

adjusting the first set of surface elements based on the calculated mapping by using the first contour as an initial estimate;

obtaining, based on the adjusted first set of surface elements, a second contour of the lesion from the treatment images obtained during the treatment session, the second contour representing the outer surface of the lesion at the second time; and

generating display data to present the second contour of the lesion on a display.

2. The method of claim 1, wherein the positioning comprises a rotational movement.

3. The method of claim 1, wherein the positioning comprises at least one of a translational movement, a scaling, and a movement in three dimensions.

4. The method of claim 1, wherein the first contour is created using at least one or more CT images, three-dimensional ultrasound images, two-dimensional ultrasound images, PET images, and MRI images.

5. The method of claim 1, further comprising receiving data representing user input from a user manually locating the first contour with respect to the treatment images.

6. The method of claim 1, wherein the first set of surface elements comprises at least one of a plurality of points, triangles, lines, shapes, other surface representations, or combinations thereof.

7. The method of claim 6, further comprising minimizing a distance between the first set of surface elements and the second set of surface elements.

8. The method of claim 7, wherein the second set of surface elements are in multiple planes.

9. The method of claim 7, wherein the second set of surface elements are within one two-dimensional plane.

10. The method of claim 9, further comprising obtaining additional surface elements from the first contour and repeating the steps of positioning, calculating, adjusting, and obtaining of claim 1.

11. The method of claim 7, wherein the mapping is determined by minimizing a mean square distance between the first set of surface elements in the first contour and the second set of surface elements in the treatment images.

12. The method of claim 6, wherein the first set of surface elements on the first contour represent an edge boundary on the planning images.

13. The method of claim 6, wherein weights are assigned to the first set of surface elements on the first contour and the weights are based at least in part on a proximity of an anatomical feature represented by the surface element to another anatomical structure of the patient on the planning images.

14. The method of claim 6, wherein weights are assigned to the second set of the surface elements and the weights are based at least in part on a density of the second set of surface elements within an area of the treatment images.

15. The method of claim 1, further comprising obtaining two-dimensional cross-sectional curves from the first contour positioned at a location corresponding to the lesion on the planning images.

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

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

18. The method of claim 1, further comprising obtaining a contoured surface representation of one or more lesions within a patient.

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

a register for storing;

(i) a first contour comprising a first set of surface elements representing an outer surface of the lesion at a first time prior to treatment, the first contour having been obtained from one or more planning images of the lesion acquired from a patient at the first time,

(ii) a set of treatment images of the lesion taken from the patient during a treatment at a second time later than the first time, and

(iii) a second set of surface elements for the lesion in at least one of the treatment images and corresponding to the lesion during the treatment at the second time;

a mapping module for calculating a mapping between the first set of surface elements of the first contour to the second set of surface elements on at least one of the treatment images; and

a processor for;

shifting the first set of surface elements of the first contour from the planning images to the second set of surface elements on the treatment images based on the mapping from the mapping module, wherein the first contour is used as an initial estimate for the shifting; and

obtaining, based on the adjusted first set of surface elements, a second contour of the lesion from the treatment images, the second contour representing the outer surface of the lesion at the second time.

20. The system of claim 19, wherein the first set of surface elements on the first contour comprise at least one member selected from the group consisting of points, triangles, and lines.

21. The system of claim 19, wherein the second set of surface elements in at least one of the treatment images comprise at least one member selected from the group consisting of points, triangles, and lines.

22. The system of claim 19, wherein the register further stores two-dimensional cross-sectional curves obtained from the shifted surface elements.

23. The system of claim 22, wherein the two-dimensional cross-sectional curves are radially offset from each other.

24. The system of claim 22, wherein the two-dimensional cross-sectional curves are parallel to each other.

25. The system of claim 19, wherein the mapping module and the processor iteratively map the first set of surface elements on the first contour to the second set of surface elements.

26. The system of claim 19, further comprising a weighting module for assigning weights to the second set of surface elements.

27. The system of claim 26, wherein the weights corresponding to the second set of surface elements indicate to a user if the second set of surface elements corresponds to a border.

28. The system of claim 26, wherein the weights further compensate for irregularities on the first contour.

29. The system of claim 26, wherein the weighting module is further configured to determine a degree of certainty to which at least a portion of the first contour corresponds to an actual anatomical feature of the patient.

30. The system of claim 19, wherein the mapping is determined by minimizing a mean square distance between the first set of surface elements on the first contour in the planning images and the second set of surface elements in at least one of the treatment images.

31. The system of claim 19, wherein the second time is substantially proximate to a treatment session.

32. The system of claim 19, wherein the register stores a plurality of initial contours, wherein each initial contour corresponds to one or more lesions within a patient.

33. One or more non-transitory computer-readable storage media having computer-executable instructions stored thereon for determining the changes to a lesion for the purpose of administering radiation treatment to the lesion, the computer-executable instructions for:

obtaining a first contour representing an outer surface of the lesion at a first time, the first contour having been obtained from one or more planning images of the lesion acquired from a patient at the first time, the first contour including a first set of surface elements;

obtaining a set of treatment images of the lesion, the treatment images having been acquired from the patient during a treatment at a second time later than the first time, wherein the treatment images include a second set of surface elements corresponding to the lesion during the treatment session at the second time;

positioning the first contour from the planning images within the set of treatment images at a location corresponding to the lesion shown on the treatment images;

calculating a mapping between the first set of surface elements and the second set of surface elements;

adjusting the first set of surface elements based on the calculated mapping by using the first contour as an initial estimate;

obtaining, based on the adjusted first set of surface elements, a second contour of the lesion from the treatment images, the second contour representing the outer surface of the lesion at the second time; and

generating display data to present the second contour of the lesion on a display.