METHOD AND APPARATUS FOR FAST VOLUME RENDERING OF 3D ULTRASOUND IMAGE

• US 20080262353A1
• Filed: 10/22/2007
• Published: 10/23/2008
• Est. Priority Date: 04/19/2007
• Status: Active Grant

• Current Assignee: Shenzhen Mindray Bio-Medical Electronics Co., Ltd. (Excelsior Union Ltd.)
• Original Assignee: Shenzhen Mindray Bio-Medical Electronics Co., Ltd. (Excelsior Union Ltd.)
• Inventors: Tian, Yong, Yao, Bin
• Granted Patent: US 8,064,723 B2
• Time in Patent Office: Days
• US Class Current: 600/443
• CPC Class Codes: A61B 8/483 involving the acquisition of a 3D volume of data
• CPC Class Codes: G01S 15/8993 Three dimensional imaging systems
• CPC Class Codes: G06T 15/08 Volume rendering

Abstract

The invention provides a method and apparatus for fast volume rendering of 3D ultrasound image, comprising a dividing step, a calculating step, a determining step, a morphological closing operation step and a filling step, wherein each flat grid can be entirely filled by obtaining gray-scale values for all pixels inside the grid through interpolating; for the non-flat grid, the steps of dividing, calculating, determining and filling are performed repeatedly until the non-flat grid is subdivided into atomic grids to calculate gray-scale values for remaining pixels by projection. As the method can be finished in the rear end, no difficulty occurs in the implementation, and no process for being adapted to previous frames is required. Therefore, the method can improve the rendering speed effectively without degrading the quality of image to put 3D ultrasound imaging to the best use.

Claims

1. A method for fast volume rendering of 3D ultrasound image, comprising steps of:

dividing a view plane into first-level grids arranged vertically and horizontally according to a predetermined size;

calculating gray-scale values of pixels on four vertices of each grid by projection;

comparing deviations among the gray-scale values of pixels on four vertices of each grid with a predetermined threshold, wherein if the deviation is smaller than the predetermined threshold, the grid is determined as a flat grid, and if the deviation is larger than the predetermined threshold, the grid is determined as a non-flat grid;

filling each flat grid by obtaining gray-scale values for all pixels inside the flat grid through interpolating the gray-scale values of pixels on four vertices thereof;

wherein for the non-flat grid, the dividing step, the calculating step, the determining step and the filling step are performed repeatedly until the non-flat grid is subdivided into atomic grids so as to calculate gray-scale values for remaining pixels by projection.

2. The method according to claim 1, further comprising step of:

a morphological closing operation for performing a morphological closing operation on a set of non-flat grids in this level each time when finishing the determining step;

wherein the non-flat grids generated in the closing operation which occur in the flat grids in this level are retained and which occur in low-level flat grids are discarded.

3. The method according to claim 1, wherein:

in the dividing step, adjacent grids can be divided to share vertices or boundaries.

4. The method according to claim 3, wherein:

in the calculating step, it is only to calculate the gray-scale values of pixels on non-sharing grids, and retrieve the calculated and saved results with regard to the gray-scale values of pixels on grids which share the vertices or boundaries.

5. The method according to claim 1, wherein:

in the dividing step, the view plane is divided into the first-level grids arranged vertically and horizontally according to a predetermined size that the width is equal to the height.

6. The method according to claim 5, wherein:

the width of the first-level grids is equal to its height and both are the integer power of 2, expressed as;

7. The method according to claim 1, wherein:

the non-flat grid is subdivided repeatedly in the dividing step into four even sub-grids shaped as , i.e. a 2×

2 array.

8. The method according to claim 1, wherein:

in the determining step, the deviation between gray-scale values of pixels on two diagonal vertices of each grid is compared with a predetermined threshold, which is expressed as follows;

9. The method according to claim 1, wherein:

in the determining step, the variance of the gray-scale values of pixels on four vertices of each grid is compared with a predetermined threshold to determine whether or not the grid is a flat or a non-flat grid.

10. The method according to claim 1, wherein:

in the filling step, the gray-scale values for all pixels inside each grid can be obtained through a bilinear or a non-linear interpolation using the gray-scale values of pixels on four vertices of each grid.

11. The method according to claim 1, wherein:

in the dividing step, dividing can be set to stop at a certain level; and

then, a ray casting algorithm is used to calculate all pixels in the non-flat grid.

12. An apparatus for fast volume rendering of 3D ultrasound image, comprising:

a dividing module for dividing a view plane into first-level grids arranged vertically and horizontally according to a predetermined size;

a calculating module for calculating gray-scale values of pixels on four vertices of each grid by projection;

a determining module for comparing deviations among the gray-scale values of pixels on four vertices of each grid with a predetermined threshold, wherein if the deviation is smaller than the predetermined threshold, the grid is a flat grid, and if the deviation is larger than the predetermined threshold, the grid is a non-flat grid; and

a filling module for entirely filling each flat grid by obtaining gray-scale values for all pixels inside the grid through interpolating the gray-scale values of pixels on four vertices thereof;

wherein the non-flat grid is processed repeatedly by the dividing module, the calculating module, the determining module and the filling module until the non-flat grid is subdivided into atomic grids so as to calculate gray-scale values for remaining pixels by projection.

13. The apparatus according to claim 12, further comprising

a morphological closing operation module for performing a morphological closing operation on a set of non-flat grids in this level each time when finishing the determining;

wherein the non-flat grids generated in the closing operation which occur in the flat grids in this level are retained and which occur in low-level flat grids are discarded.

14. The apparatus according to claim 12, wherein:

the dividing module can divide the adjacent grids to share vertices or boundaries.

15. The apparatus according to claim 14, wherein:

the calculating module only calculates gray-scale values of pixels on non-shared grids, and retrieves the calculated and saved result with regard to the gray-scale values of pixels on grids which share the vertices or boundaries.

16. The apparatus according to claim 12, wherein:

the dividing module divides the view plane into the first-level grids arranged vertically and horizontally according to a predetermined size that the width is equal to the height.

17. The apparatus according to claim 16, wherein:

the width of the first-level grids is equal to its height and both are the integer power of 2, expressed as;

18. The apparatus according to claim 12, wherein:

the non-flat grid is subdivided repeatedly by the dividing module into four even sub-grids shaped as i.e. a 2×

2 array.

19. The apparatus according to claim 12, wherein:

the determining module compares the deviation between the gray-scale values of pixels on two diagonal vertices of each grid with a predetermined threshold, which is expressed as follows;

20. The apparatus according to claim 12, wherein:

the determining module determines whether or not the grid is a flat or a non-flat grid by comparing the variance of the gray-scale values of pixels on four vertices of each grid with a predetermined threshold.

21. The apparatus according to claim 12, wherein:

the filling module can obtain the gray-scale values of all pixels inside each grid through a bilinear or a non-linear interpolation using the gray-scale values of pixels on four vertices of each grid.

22. The apparatus according to claim 12, wherein:

the dividing module can be set to stop at a certain level; and

then, a ray casting algorithm is used to calculate all pixels in the non-flat grid.