Tomosynthesis gain calibration and image correction

1. A method for gain calibration at a plurality of imaging parameters for a tomosynthesis sweep, the method comprising:

performing one or more tomosynthesis sweeps to acquire a plurality of tomosynthesis projection x-ray images, each of the plurality of tomosynthesis projection x-ray images associated with one of the plurality of imaging parameters:

generating a high-dose x-ray image by averaging the plurality of tomosynthesis projection x-ray images:

generating a high-dose gain map associated with the high-dose x-ray image:

generating a plurality of low-dose gain maps, each of the plurality of low-dose gain maps associated with one of the plurality of tomosynthesis projection x-ray images associated with one of the plurality of imaging parameters:

decomposing each of the plurality of low-dose gain maps into a plurality of component levels:

extracting low-resolution components from the plurality of component levels for each of the plurality of low-dose gain maps; and

for each of the plurality of imaging parameters, combining the high-dose gain map with the each of the low-resolution components of the low-dose gain maps to generate a final gain map for each of the plurality of imaging parameters.

2. The method of claim 1 , further comprising:

storing the final gain map for each of the plurality of imaging parameters:

acquiring tomosynthesis x-ray images of a patient's breast at each of the plurality of imaging parameters; and

gain correcting the tomosynthesis x-ray images of the patient's breast using the stored final gain map for each of the plurality of imaging parameters to produce gain-corrected breast images.

3. The method of any of claims 1-2 , wherein the imaging parameters includes one of: projection angle, kVp, filter material type, breast thickness and grid position.

4. The method of any of claims 1-3 , wherein the one or more tomosynthesis sweeps are performed by an image acquisition unit comprising an x-ray source and an x-ray image receptor, wherein the image acquisition unit acquires projection x-ray images of an object at the plurality of imaging parameters.

5. The method of any of claims 1-4 , wherein generating the high-dose gain map comprises:

determining a mean signal count for an array of pixels associated with the high-dose x-ray image:

determining a raw signal count for each of the pixels from the array of pixels associated with the high-dose x-ray image:

calculating the gain correction coefficient for each of the pixels in the array of pixels associated with the high-dose x-ray image, wherein the gain correction coefficient is a product of the mean signal count and an inverse of the raw signal count for the particular pixel; and

assembling the gain correction coefficient for each of the pixels in the array of pixels into the high-dose gain map.

6. The method of any of claims 1-5 , wherein decomposing each of the plurality of low-dose gain maps includes decomposing into a plurality of resolution levels, wherein each level of the plurality of resolution levels includes a detail image and a residual image.

7. The method of claim 6 , wherein decomposing each of the plurality of low-dose gain maps is performed using a multi-scale decomposition process.

8. The method of any of claims 6-7 , wherein extracting the low-resolution components includes extracting low-resolution components from the residual image of a last level of the plurality of resolution levels.

9. The method of any of claims 1-8 , wherein the high-dose gain map comprises x-ray detector pixel-to-pixel gain variation data.

10. The method of any of claims 1-9 , wherein the low-resolution components comprise one of: an angle data, a kV data, a filter data, a grid data, and a thickness data.

11. A tomosynthesis imaging system for gain calibration at a plurality of projection angles, the system comprising:

an image acquisition unit comprising an x-ray source and an x-ray image receptor, wherein the image acquisition unit acquires projection x-ray images of an object at the plurality of projection angles:

a processor:

memory including instructions that when executed by the processor cause the processor to:

perform one or more tomosynthesis sweeps to acquire a plurality of tomosynthesis projection x-ray images, each of the plurality of tomosynthesis projection x-ray images associated with one of the plurality of projection angles:

generate a high-dose x-ray image by averaging the plurality of tomosynthesis projection x-ray images:

generate a high-dose gain map associated with the high-dose x-ray image:

decompose the high-dose gain map into a first plurality of component levels:

extract a high-resolution component from the first plurality of component levels:

generate a plurality of low-dose gain maps, each of the plurality of low-dose gain maps associated with one of the plurality of tomosynthesis projection x-ray images associated with one of the plurality of projection angles:

decompose each of the plurality of low-dose gain maps into a second plurality of component levels:

extract low-resolution components from each of the plurality of low-dose gain maps, wherein the low-resolution components comprise an angle map; and

for each of the plurality of projection angles, combine the high-resolution component of the high-dose gain map with the each of the low-resolution components of the low-dose gain maps to generate a final gain map for each of the plurality of projection angles.

12. The system of claim 11 , wherein the instructions when executed by the processor further cause the processor to:

store the final gain map for each of the plurality of projection angles:

acquire tomosynthesis x-ray images of a patient's breast at each of the plurality of projection angles; and

gain correct the tomosynthesis x-ray images of the patient's breast using the stored final gain map for each of the plurality of projection angles to produce gain-corrected breast images.

13. The system of any of claims 11-12 , wherein the one or more tomosynthesis sweeps are performed to acquire a plurality of tomosynthesis projection x-ray images of a phantom.

14. The system of any of claims 11-13 , wherein the instructions when executed by the processor to generate the high-dose gain map cause the processor to:

determine a mean signal count for an array of pixels associated with the high-dose x-ray image:

determine a raw signal count for each of the pixels from the array of pixels associated with the high-dose x-ray image:

calculate the gain correction coefficient for each of the pixels in the array of pixels associated with the high-dose x-ray image, wherein the gain correction coefficient is a product of the mean signal count and an inverse of the raw signal count for the particular pixel; and

assemble the gain correction coefficient for each of the pixels in the array of pixels into the high-dose gain map.

15. The system of any of claims 11-14 , wherein decomposing the high-dose gain map and decomposing each of the plurality of low-dose gain maps includes decomposing into a plurality of resolution levels, wherein each level of the plurality of resolution levels includes a detail image and a residual image.

16. The system of claim 15 , wherein decomposing the high-dose gain map and decomposing each of the plurality of low-dose gain maps is performed using a multi-scale decomposition process.

17. The system of any of claims 15-16 , wherein extracting the high-resolution component includes extracting a high-resolution component from the detail image of a level above a last level of the plurality of resolution levels and extracting the low-resolution components includes extracting low-resolution components from the residual image of a last level of the plurality of resolution levels.

18. The system of any of claims 11-17 , wherein the high-resolution component comprises x-ray detector pixel-to-pixel gain variation data.

19. The system of any of claims 11-18 , wherein the low-resolution components further comprise one of an angle data, a kV data, a filter data, a grid data, and a thickness data.

20. A method for gain calibration at a plurality of projection angles for a tomosynthesis sweep, the method comprising:

performing one or more tomosynthesis sweeps to acquire a plurality of tomosynthesis projection x-ray images, each of the plurality of tomosynthesis projection x-ray images associated with one of the plurality of projection angles:

generating a high-dose x-ray image by averaging the plurality of tomosynthesis projection x-ray images:

generating a high-dose gain map associated with the high-dose x-ray image:

decomposing the high-dose gain map into a first plurality of component levels:

extracting a high-resolution component from the first plurality of component levels:

generating a plurality of low-dose gain maps, each of the plurality of low-dose gain maps associated with one of the plurality of tomosynthesis projection x-ray images associated with one of the plurality of projection angles:

decomposing each of the plurality of low-dose gain maps into a second plurality of component levels;

extracting low-resolution components from each of the plurality of low-dose gain maps, wherein the low-resolution components comprise an angle map; and

for each of the plurality of projection angles, combining the high-resolution component with the each of the low-resolution components to generate a final gain map for each of the plurality of projection angles.