Method and system for reconstructing cone-beam projection data with reduced artifacts

1. A method for generating an image of an object, the method comprising:

acquiring projection data at one or more projection views, wherein the projection data is acquired along a circular scan trajectory;

generating a corrected projection dataset by:

computing a correction term for a subset of the projection data to generate a weighted filtered projection dataset corresponding to the subset;

for a remainder of the projection data, applying a ramp filter to the remainder of the projection data and weighting the ramp filtered remainder of the projection data to generate a ramp filtered weighted projection dataset;

combining the weighted filtered projection dataset and the ramp filtered weighted projection dataset to generate a corrected projection dataset; and

backprojecting the corrected projection dataset along one or more projection rays associated with one or more of the projection views, to generate a reconstructed image of the object.

2. The method of claim 1 , wherein generating the correction term comprises applying a derivative to the subset of the projection data.

3. The method of claim 1 , wherein computing the correction term comprises applying a derivative to at least the subset of the projection data, and performing a Hilbert filtering of the subset of the projection data to generate a filtered projection dataset.

4. The method of claim 3 , wherein the derivative is applied to at least the subset of the projection data in a direction parallel to the axis of rotation of a CT scanner.

5. The method of claim 3 , wherein the Hilbert filtering of the subset of the projection data is performed along one or more detector rows.

6. The method of claim 3 , wherein computing the correction term further comprises weighting the filtered projection dataset based upon a derivative of a view weight, computed for one or more of the projection views.

7. The method of claim 6 , wherein the filtered projection dataset is further weighted based on one or more cone angles associated with one or more of the projection views.

8. The method of claim 1 , wherein the projection data comprises cone-beam projection data.

9. A method for generating an image of an object, the method comprising:

acquiring projection data at one or more projection views, wherein the projection data is acquired along a helical scan trajectory;

processing the projection data by:

computing a correction term for a subset of the projection data to generate a filtered projection dataset corresponding to the subset;

for a remainder of the projection data, applying a ramp filter to the remainder of the projection data and weighting the ramp filtered remainder of the projection data to generate a ramp filtered projection dataset;

computing a corrected projection data value for each voxel by weighting one or more projection data values of the ramp filtered projection dataset using a standard weight factor and weighting one or more projection data values of the filtered projection dataset using a correction weight factor; and

performing a backprojection of the corrected data value computed for each voxel to generate a reconstructed image of the object.

10. The method of claim 9 , wherein computing the correction term comprises applying a derivative to the subset of the projection data and performing a Hilbert filtering of the subset of the projection data to generate the filtered projection dataset.

11. The method of claim 10 , wherein the derivative is applied to at least the subset of the projection data in a direction that is substantially parallel to the axis of rotation of a CT scanner.

12. The method of claim 10 , wherein the Hilbert filtering of the subset of the projection data is performed along one or more detector rows.

13. The method of claim 9 , wherein the standard weight factor is computed as a function of at least one of a detector row, a detector column, the view angle associated with each projection view and the position of each voxel along a projection ray.

14. The method of claim 9 , wherein the correction weight factor is computed based on computing at least one of a cone angle associated with a projection ray and one or more data values of the partial derivatives of the standard weight factor computed for the projection rays.

15. The method of claim 9 , wherein the projection data is acquired using a computed tomography (CT) system.

16. The method of claim 9 , wherein the projection data comprises cone-beam projection data.

17. A computed tomography (CT) system for generating an image of an object, the system comprising:

an x-ray source configured to project an x-ray beam from a plurality of positions through the object;

a detector configured to produce a plurality of electrical signals corresponding to the x-ray beam; and

a processor configured to process the plurality of electrical signals to generate projection data, to compute a correction term for a subset of the projection data to generate a weighted filtered projection dataset corresponding to the subset, to apply a ramp filter to a remainder of the projection data and weight the ramp filtered remainder of the projection data to generate a ramp filtered weighted projection dataset, to combine the weighted filtered projection dataset and the ramp filtered weighted projection dataset to generate a corrected projection dataset, and to backproject the corrected projection dataset along one or more projection rays associated with one or more of the projection views, to generate a reconstructed image of the object, wherein the projection data is acquired along a circular scan trajectory, along one or more projection views.

18. A computed tomography (CT) system for generating an image of an object, the system comprising:

an x-ray source configured to project an x-ray beam from a plurality of positions through the object;

a detector configured to produce a plurality of electrical signals corresponding to the x-ray beam; and

a processor configured to process the plurality of electrical signals to generate projection data, to compute a correction term for a subset of the projection data to generate a filtered projection dataset corresponding to the subset; to apply a ramp filter to a remainder of the projection data and weight the ramp filtered remainder of the projection data to generate a ramp filtered projection dataset, to compute a corrected projection data value for each voxel by weighting one or more projection data values of the ramp filtered projection dataset using a standard weight factor and weighting one or more projection data values of the filtered projection dataset using a correction weight factor, to perform a backprojection of the corrected data value computed for each voxel to generate a reconstructed image of the object, wherein the projection data is acquired along a helical scan trajectory, along one or more projection views.