Automatic navigation for virtual endoscopy

• US 20030152897A1
• Filed: 12/18/2002
• Published: 08/14/2003
• Est. Priority Date: 12/20/2001
• Status: Abandoned Application

• Current Assignee: Siemens Medical Solutions USA Incorporated (Siemens AG)
• Original Assignee: Siemens Medical Solutions USA Incorporated (Siemens AG)
• Inventors: Geiger, Bernhard
• Application Number:
  US10/322,326
• Publication Number:
  US 20030152897A1
• Time in Patent Office: Days
• US Class Current: 434/262
• CPC Class Codes: G06T 15/00 3D [Three Dimensional] image rendering

Abstract

A method for navigating a viewpoint of a virtual endoscope in a lumen of a structure is provided. The method includes the steps of (a)determining an initial viewpoint of the virtual endoscope, the initial viewpoint having a first center point and first direction; (b)determining a longest ray from the initial viewpoint to the lumen, the longest ray having a first longest ray direction; (c)determining a second direction between the first direction of the initial viewpoint and the first longest ray direction; (d)turning the viewpoint to the second direction and moving the initial viewpoint a first predetermined distance in a first direction of the initial viewpoint; (e)calculating a second center point of the viewpoint; (f)moving the viewpoint to the second center point; and repeating steps (b) through (f) until the viewpoint reaches an intended target.

Claims

1. A method for navigating a viewpoint of a virtual endoscope in a lumen of a structure, the method comprising the steps of:

(a)determining an initial viewpoint of the virtual endoscope, the initial viewpoint having a first center point. and first direction;

(b)determining a longest ray from the initial viewpoint to the lumen, the longest ray having a first longest ray direction;

(c)determining a second direction between the first direction of the initial viewpoint and the first longest ray direction;

(d)turning the viewpoint to the second direction and moving the initial viewpoint a first predetermined distance in a first direction of the initial viewpoint;

(e)calculating a second center point of the viewpoint; and

(f)moving the viewpoint to the second center point.

2. The method as in claim 1, further comprising the step of repeating steps (b) through (f) until the viewpoint reaches an intended target.

3. The method as in claim 1, further comprising the step of rendering a three-dimensional (3D) image of the structure.

4. The method as in claim 3, wherein the rendering step further includes scanning the structure to acquire a plurality, of two-dimensional (2D) images and rendering the 3D image from the plurality of 2D images.

5. The method as in claim 3, wherein the determining a longest ray step and the rendering step are performed by a raycasting image rendering technique.

6. The method as in claim 1, wherein the second direction of the viewpoint is determined as a weighted sum of the first direction of the initial viewpoint and the first longest ray direction.

7. The method as in claim 6, wherein the weighted sum is calculated as

V′

=wR+(1−

w)V

where V is the direction of the initial viewpoint, R is the first longest ray direction and w is a weight factor.

9. The method as in claim 1, wherein the calculating a second center point comprises the steps of:

casting a plurality of rays in a plane perpendicular to second direction of the viewpoint;

determining an intersection point of each of the plurality of rays with the lumen; and

determining an average of the intersection points as the second center point.

10. The method as in claim 1, wherein the calculating a second center point comprises the steps of:

determining a plurality of planes intersecting the first center point, each plane having a different orientation;

casting a plurality of rays in each of the plurality of planes;

determining an intersection point of each of the plurality of rays with the lumen; and

determining an average of the intersection points as the second center point.

8. The method as in 7, wherein the weight factor w is calculated as

w=minimum(abs(d/f), 1.0)

where d is the first predetermined distance and f is a scaling factor.

11. A program storage device readable by a machine, tangibly embodying a program of instructions executable by the machine to perform method steps for navigating a viewpoint of a virtual endoscope in a lumen of a structure, the method steps comprising:

(a)determining an initial viewpoint of the virtual endoscope, the initial viewpoint having a first center point and first direction;

(b)determining a longest ray from the initial viewpoint to the lumen, the longest ray having a first longest ray direction;

(c)determining a second direction between the first direction of the initial viewpoint and the first longest ray direction;

(d)turning the viewpoint to the second direction and moving the initial viewpoint a first predetermined distance in a first direction of the initial viewpoint;

(e)calculating a second center point of the viewpoint; and

(f)moving the viewpoint to the second center point.

12. The program storage device as in claim 11, further comprising the step of repeating steps (b) through (f) until the viewpoint reaches an intended target.

13. The program storage device as in claim 11, further comprising the step of rendering a three-dimensional (3D) image of the structure.

14. The program storage device as in claim 13, wherein the rendering step further includes scanning the structure to acquire a plurality of two-dimensional (2D) images and rendering the 3D image from the plurality of 2D images.

15. The program storage device as in claim 13, wherein the determining a longest ray step and the rendering step are performed by a raycasting image rendering technique.

16. The program storage device as in claim 11, wherein the second direction of the viewpoint is determined as a weighted sum of the first direction of the initial viewpoint and the first longest ray direction.

17. The program storage device as in claim 16, wherein the weighted sum is calculated as

V′

=wV+(1−

w)R

Where V is the direction of the initial viewpoint, R is the first longest ray direction and w is a weight factor.

19. The program storage device as in claim 11, wherein the calculating a second center point comprises the steps of:

determining a plurality of planes intersecting the first center point, each plane having a different orientation;

casting a plurality of rays in each of the plurality of planes;

determining an intersection point of each of the plurality of rays with the lumen; and

determining an average of the intersection points as the second center point.

18. The program storage device as in 17, wherein the weight factor w is calculated as

w=minimum(abs(d/f), 1.0)

where d is the first predetermined distance and f is a scaling factor.

20. A system for virtual endoscopy comprising:

an image renderer for rendering a three-dimensional (3D) image of a structure from a plurality of two-dimensional (2D) images;

a processor for navigating a viewpoint of a virtual endoscope in the 3D image of the structure; and

a display device for displaying the viewpoint.

21. The system as in claim 20, wherein the processor determines an initial viewpoint of the virtual endoscope, the initial viewpoint having a first center point and first direction, determines a longest ray from the initial viewpoint to the lumen, the longest ray having a first longest ray direction, determines a second direction between the first direction of the initial viewpoint and the first longest ray direction, turns the viewpoint to the second direction and moves the initial viewpoint a first predetermined distance in a first direction of the initial viewpoint, calculates a second center point of the viewpoint, and moves the viewpoint to the second center point.

22. The system as in claim 20, further comprising a scanner device for scanning the plurality of two-dimensional (2D) images of the structure.

23. The system as in claim 21, further comprising a cursor control device for determining a speed of movement of the viewpoint.