Method and system for tomosynthesis projection image enhancement and review

1. A method for obtaining at least one enhanced image of an object of interest using a system comprising an X-ray source facing an X-ray detector, the method comprising:

moving the X-ray source to a plurality of positions relative to the X-ray detector, the X-ray detector being stationary, and acquiring a 2D tomosynthesis projection image of the object of interest at each of the plurality of positions;

enhancing each acquired 2D tomosynthesis projection image;

projecting each enhanced image on an isocentric virtual X-ray detector to produce a plurality of virtual projections, wherein the normal to the isocentric virtual X-ray detector points towards the X-ray source for each position of the plurality positions to produce a plurality of virtual projections;

displaying successively the virtual projection images;

enhancing a selected projection image of the acquired 2D tomosynthesis projection images using at least a subset of the acquired tomosynthesis projection images at a plurality of heights, wherein a most likely height is determined for each pixel (i, j) of the selected projection image, and wherein enhancing the selected projection image comprises:

for each pixel (i, j) of the selected projection image and for a given height, accumulating gray level intensity values of the corresponding pixel position in at least one of the tomosynthesis projection images;

ranking the accumulated gray level intensity values for each pixel over all possible heights;

determining the most likely height for each pixel (i, j) by selecting a maximum accumulated gray level intensity value; and

combining each pixel's (i, j)'s gray level intensity level with the accumulated gray level intensity value at a height corresponding to the most likely height for pixel (i, j); and

displaying an enhanced 2D projection image.

2. The method according to claim 1 , wherein the displaying step is performed at an adjustable speed.

3. The method according to claim 1 , wherein the accumulating step is performed for different frequency bands obtained by filtering the acquired 2D tomosynthesis projection images.

4. The method according to claim 3 , wherein the most likely height of each pixel (i, j) is obtained by: filtering the acquired 2D tomosynthesis projection images;

for each pixel (i, j) of the selected projection image and for a given height, accumulating the filtered gray level intensity values of the corresponding pixel position in at least one of the 2D tomosynthesis projection images;

deriving energy values from the accumulated gray level intensity values;

optionally spatially smoothing the energy values of a given height; and

determining the most likely height for each pixel (i, j) by selecting the maximum energy value among all possible heights.

5. The method according to claim 1 , wherein the most likely height of each pixel (i, j) is obtained as a combination of maximum accumulated gray level intensity values and 3D marks provided by a computer-aided diagnosis (CAD) system or indicated by a user through a 3D review system.

6. The method according to claim 1 , wherein the most likely height of each pixel (i, j) is stored as a height map associated to the enhanced 2D projection image.

7. The method according to claim 1 , wherein the selected projection image is the central projection (0°), which is the projection perpendicular to the X-ray detector.

8. The method according to claim 1 , wherein at least one 2D tomosynthesis projection image is denoised prior to improving the image quality of at least one of the at least one 2D tomosynthesis projection image.

9. A system for obtaining enhanced images of an object of interest comprising:

an imaging system comprising an X-ray source and an X-ray detector configured to acquire 2D tomosynthesis projection images of the object of interest by moving the X-ray source to a plurality of positions relative to the X-ray detector, wherein a 2D tomosynthesis projection image is acquired at each of the plurality of positions;

a processing unit configured enhance each of the acquired 2D tomosynthesis projection images, and project each enhanced image on an isocentric virtual X-ray detector to produce a plurality of virtual projections, wherein the normal to the isocentric virtual detector points towards the X-ray source for each position of the plurality positions to produce a plurality of virtual projections;

a display configured to successively display the virtual projections;

wherein the processing unit is further configured to compute an enhancement for a selected projection image of the acquired 2D tomosynthesis projection images using at least a subset of the acquired 2D tomosynthesis projection images at a plurality of heights, wherein a most likely height is determined for each pixel (i, j) of the selected projection image, and wherein in computing the enhancement, the processing unit is further configured to:

for each pixel (i, j) of the selected projection image and for a given height, accumulate the gray level intensity values of the corresponding pixel position in at least one of the 2D tomosynthesis projection images;

rank the accumulated gray level intensity values for each pixel over all possible heights;

determine the most likely height for each pixel (i, j) by selecting the maximum accumulated gray level intensity value; and

combine pixel (i, j)'s gray level intensity value with the determined maximum gray level intensity values for each pixel (i, j); and

the display is configured to display an enhanced projection image.

10. The system according to claim 9 , wherein the object of interest is a patient's breast.

11. The system according to claim 9 , wherein the most likely height of each pixel (i, j) is obtained as a combination of maximum accumulated gray level intensity value and 3D marks provided by a CAD system or indicated by a user through a 3D review system.

12. The system according to claim 11 , wherein the most likely height of each pixel (i, j) is stored as a height map associated to the enhanced 2D projection image.

13. The system according to claim 9 , wherein the selected projection image is the central projection (0°), which is the projection perpendicular to the X-ray detector.

14. The system according to claim 9 , wherein at least one 2D tomosynthesis projection image is denoised prior to improving the image quality of at least one of the at least one 2D tomosynthesis projection image.