METHOD FOR PROCESSING TOMOSYNTHESIS ACQUISITIONS IN ORDER TO OBTAIN A REPRESENTATION OF THE CONTENTS OF AN ORGAN

• US 20110150178A1
• Filed: 12/22/2010
• Published: 06/23/2011
• Est. Priority Date: 12/22/2009
• Status: Active Grant

• Current Assignee: General Electric Company
• Original Assignee: General Electric Company
• Inventors: Bernard, Sylvain, Iordache, Razvan, Souchay, Henri
• Granted Patent: US 9,842,415 B2
• Time in Patent Office: Days
• US Class Current: 378/22
• CPC Class Codes: G06T 11/008 Specific post-processing after tomographic reconstruction, e.g. voxelisation, metal artifact correction
• CPC Class Codes: G06T 2207/10112 Digital tomosynthesis [DTS]
• CPC Class Codes: G06T 2211/436 Limited angle

Abstract

A method for processing tomosynthesis images of an object of interest, using an imaging system, the imaging system comprising an X-ray source positioned facing a detector on which the object of interest is positioned. With the method of an embodiment of the invention, it is possible to obtain a representation of the contents of an organ.

Claims

1. A method for processing tomosynthesis images of an object of interest, using an imaging system, the imaging system comprising an X-ray source positioned facing a detector on which the object of interest is positioned, the method comprising the following steps:

acquiring a plurality of 2D projection images of the object of interest according to a plurality of orientations located with respect to the perpendicular to the detector, a zero orientation being the closest to the perpendicular;

applying a filter on the acquired 2D projection images so as to obtain filtered projection images of the object of interest;

determining reconstruction slices of the object of interest from at least two of the filtered projections, the whole of the reconstruction slices being the filtered reconstructed volume of the object of interest;

backprojecting reconstruction slices according to a determined orientation direction, the determined direction preferably being the so-called zero orientation direction, so as to obtain an intermediate 2D image of the object of interest; and

obtaining a final 2D image of the object of interest by combining the intermediate 2D image and the projection image corresponding to the determined orientation.

2. The method according to claim 1, wherein the filter applied to the projection images is a high pass filter, the characteristics of which preferably depend on the thickness of the object of interest.

3. The method according to any claim 1, wherein the reconstruction slices are determined by a non-linear backprojection algorithm.

4. The method according to any claim 1, wherein the backprojection of the reconstruction slices is an SIP reprojection in the determined orientation direction, the SIP reprojection consisting, for each pixel of the intermediate 2D image, in determining in the filtered reconstructed volume, an intensity voxel calculated by using sorting of the values of pixels along the ray from the source to the pixel of the intermediate 2D image and in storing in the memory unit of the imaging system, an identifier of the reconstruction slice in which is found the voxel from the sorting, so as to have in the memory unit, depth information (argMax) connecting each pixel of the intermediate 2D image to the associated reconstruction slice from which this pixel stems.

5. The method according to claim 1, wherein the reprojection of the reconstruction slices is an MIP reprojection in the determined orientation direction, the MIP reprojection consisting, for each pixel of the intermediate 2D image, in determining, in the filtered reconstructed volume, the maximum intensity voxel along the ray from the source to the pixel of the intermediate 2D image and in storing in the memory unit of the imaging system, an identifier of the reconstruction slice in which the maximum intensity voxel is found, so as to have in the memory unit, depth information (argMax) connecting each pixel of the intermediate 2D image to the associated reconstruction slice from which this pixel stems.

6. The method according to claim 1, comprising a step for determining a volume, obtained using a system for automatic detection of lesions, wherein each voxel represents a probability of belonging to a lesion.

7. The method according to claim 6, wherein the reprojection of the reconstruction slices consists in any pixel of the intermediate 2D image in selecting the voxel with the highest probability of belonging to a lesion along the ray from the source to this pixel, and in storing in the memory unit of the imaging system, an identifier of the reconstruction slice in which the voxel of maximum probability is found, in order to have in the memory unit, depth information (argMax) connecting each pixel of the intermediate 2D image to the associated reconstruction slice from which this pixel stems.

8. The method according to claim 4, further comprising:

a step for local regularization, by the processing unit, of depth information (argMax), so as to obtain regularized depth information (argMax′

).

9. The method according to claim 1, further comprising:

prior to the determination step of the final 2D image, a step for applying a filter to the projection image corresponding to the determined orientation so as to obtain a filtered projection image corresponding to the determined orientation, the determination of the final 2D image consisting in the combination of the intermediate 2D image and the filtered projection image corresponding to the determined orientation.

10. The method according to claim 9, wherein the filter applied to the projection image corresponding to the determined orientation of the object of interest is a low pass filter.

11. The method according to claim 1, wherein the final 2D image is determined for each orientation.

12. The method according to claim 1, further comprising:

determining display slices obtained from 2D projection images, the whole of the display slices being the reconstructed volume of the object of interest.

13. A display method for displaying a set of radiography images of an object of interest by a unit for displaying radiography images, the radiographic images being the display slices of the object of interest and a final 2D image of the object of interest obtained by a method for processing tomosynthesis images according to claim 9, the depth information (argMax′

) being stored in the memory unit (14), the display method comprising;

displaying the final 2D image on the display unit,

selecting a pixel from the final 2D image;

searching, among the depth information (argMax′

) stored in the memory unit, for an identifier of the reconstruction slice associated with the selected pixel;

adjusting the size of the display slice associated with the selected pixel to the size of the final 2D image; and

displaying by means of the display unit, the adjusted display slice and associated with the selected pixel.

14. The display method according to claim 13, further comprising:

following the display of the adjusted display slice, returning to a display of the final 2D image.

15. A display method for displaying a set of radiography images of an object of interest by a unit for displaying radiography images, the radiographic images being the display slices of the object of interest and a final 2D image of the object of interest obtained by a method for processing tomosynthesis images according to claim 9, the display method comprising:

displaying a display slice on the display unit;

adjusting the size of the final 2D image to a size of the display slice; and

displaying on demand from the user, on the display unit, the adjusted final 2D image.

16. The display method according to claim 15, further comprising:

following the display of the adjusted final 2D image, returning to a display of the display slice.

17. An imaging system comprising an X-ray detection, a source emitting X-rays, a processing unit and means for applying a processing method according to claim 1.