System and method for image reconstruction

1. An image reconstruction method comprising:

obtaining image data, at least a portion of the image data relating to a region of interest (ROI);

determining local information of the image data, wherein the local information including orientation information of the image data and gradient information of the image data;

determining a regularization item based on a product of the orientation information of the image data and the gradient information of the image data, wherein the orientation information of the image data is modified by an Eigenvalue adjustment function that includes a factor of a scale of the Eigenvalues and at least one factor of a location of a peak of a characteristic curve;

modifying the image data based on the regularization item; and

generating an image based on the modified image data.

2. The method of claim 1 , the determining a regularization item based on the local information comprising:

smoothing the image data;

determining orientation information of the smoothed image data; and

determining the regularization item based on the gradient information of the image data and the orientation information of the smoothed image data.

3. The method of claim 2 , the smoothing the image data comprising smoothing the image data based on a first low-pass filter.

4. The method of claim 2 , the orientation information comprising a structure tensor of the smoothed image data or a modified structure tensor of the smoothed image data.

5. The method of claim 4 , the determining orientation information of the smoothed image data comprising:

determining the structure tensor of the smoothed image data;

smoothing the structure tensor;

determining Eigenvalues of the smoothed structure tensor;

modifying the Eigenvalues; and

determining a modified structure tensor based on the modified Eigenvalues.

6. The method of claim 5 , the modifying the Eigenvalues comprising:

determining the Eigenvalue adjustment function based on the at least a portion of the image data relating to the ROI; and

revising the Eigenvalues based on the Eigenvalue adjustment function.

7. The method of claim 6 , the ROI comprising a region relating to a liver, a bone, or a kidney.

8. The method of claim 5 , the determining the structure tensor of the smoothed image data comprising:

determining a first-order differentiation of the smoothed image data;

determining a transpose of the first-order differentiation of the smoothed image data; and

determining the structure tensor of the smoothed image data based on the first-order differentiation of the smoothed image data and the transpose of the first-order differentiation of the smoothed image data.

9. The method of claim 5 , the smoothing the structure tensor comprising applying a second low-pass filter on the structure tensor.

10. The method of claim 2 , the determining gradient information of the image data comprising determining the gradient information based on a first-order differentiation of the image data.

11. The method of claim 1 , the obtaining image data comprising:

obtaining projection data; and

generating the image data based on the projection data.

12. The method of claim 11 , the generating the image data based on the projection data comprising updating the image data based on an iterative statistical reconstruction algorithm.

13. The method of claim 1 , the image data comprising a 2D image, 2D image data, a 3D image, or 3D image data.

14. An image reconstruction method comprising:

obtaining image data, at least a portion of the image data relating to a region of interest (ROI);

determining gradient information of the image data;

determining a structure tensor of the image data;

determining a regularization item based on a product of the gradient information and the structure tensor, wherein the structure tensor is modified by an Eigenvalue adjustment function that includes a factor of a scale of the Eigenvalues and at least one factor of a location of a peak of a characteristic curve;

modifying the image data based on the regularization item; and

generating an image based on the modified image data.

15. The method of claim 14 , the determining a structure tensor of the image data comprising:

optimizing the structure tensor by smoothing algorithm or/and modifying algorithm.

16. The method of claim 15 , wherein the smoothing algorithm includes Gaussian filter, and the modifying algorithm includes the Eigenvalue adjustment function.

17. A system, comprising:

at least one storage medium including a set of instructions for image reconstruction; and

at least one processor configured to communicate with the at least one storage medium, wherein the set of instructions, when executed by the at least one processor, cause the system to perform operations including:

obtaining image data, at least a portion of the image data relating to a region of interest (ROI);

determining local information of the image data, the local information including orientation information of the image data and gradient information of the image data;

determining a regularization item based on a product of the orientation information of the image data and the gradient information of the image data, wherein the orientation information of the image data is modified by an Eigenvalue adjustment function that includes a factor of a scale of the Eigenvalues and at least one factor of a location of a peak of a characteristic curve;

modifying the image data based on the regularization item; and

generating an image based on the modified image data.

18. The system of claim 17 , the operations further including:

smoothing the image data;

determining orientation information of the smoothed image data; and

determining the regularization item based on the gradient information of the image data and the orientation information of the smoothed image data.

19. The system of claim 18 , the operations further including:

determining a structure tensor of the smoothed image data;

smoothing the structure tensor;

determining Eigenvalues of the smoothed structure tensor;

modifying the Eigenvalues; and

determining a modified structure tensor based on the modified Eigenvalues.

20. The system of claim 17 , the operations further including:

determining the Eigenvalue adjustment function based on the at least a portion of the image data relating to the ROI; and

revising the Eigenvalues based on the Eigenvalue adjustment function.