Systems and methods for scatter correction of image

1. A system, comprising:

at least one storage device including a set of instructions for scatter correction of an image; and

at least one processor configured to communicate with the at least one storage device, wherein when executing the set of instructions, the at least one processor is configured to direct the system to:

obtain an image of a subject, the image being generated by operating an X-ray imaging device to perform a first scan on the subject;

obtain a reference image of air, the reference image being generated by operating the X-ray imaging device to perform a second scan on the air;

identify an object of interest (OOI) from the image, the OOI including one or more pixels;

for each pixel of the one or more pixels of the OOI,

determine, based on a pixel value of the each pixel and the reference image, an equivalent thickness of the OOI corresponding to the each pixel, the equivalent thickness of the OOI corresponding to the pixel being a travelling distance of radiation photon(s) corresponding to the pixel through the subject;

determine a scatter correction coefficient of the each pixel based at least in part on the equivalent thickness of the OOI corresponding to the each pixel; and

correct the pixel value of the each pixel using the corresponding scatter correction coefficient.

2. The system of claim 1 , wherein to determine the equivalent thickness of the OOI corresponding to the each pixel, the at least one processor is further configured to direct the system to:

for each candidate pixel of one or more candidate pixels in the OOI, determine a thickness of the OOI corresponding to the each candidate pixel based on a pixel value of the each candidate pixel and the reference image;

determine, based on the thicknesses of the OOI corresponding to the one or more candidate pixels, an average thickness of the OOI corresponding to the one or more candidate pixels; and

designate the average thickness of the OOI corresponding to the one or more candidate pixels as the equivalent thickness of the OOI corresponding to the each pixel.

3. The system of claim 2 , wherein to determine a thickness of the OOI corresponding to the each candidate pixel based on a pixel value of the each candidate pixel and the reference image, the at least one processor is further configured to direct the system to:

determine a ratio of the pixel value the each candidate pixel in the image of the subject to a pixel value of a pixel in the reference image corresponding the each candidate pixel; and

determine the thickness of the OOI corresponding to the each candidate pixel based on the ratio and a linear attenuation coefficient of the OOI.

4. The system of claim 1 , wherein to determine the equivalent thickness of the OOI corresponding to the each pixel, the at least one processor is further configured to direct the system to:

identify the OOI into a plurality of sub-areas;

for each of the sub-areas,

for each candidate pixel of one or more candidate pixels in the sub-area, determine a thickness of the OOI corresponding to the each candidate pixel based on a pixel value of the each candidate pixel and the reference image;

determine, based on the thicknesses of the OOI corresponding to the one or more candidate pixels in the sub-area, an average thickness of the sub-area corresponding to the one or more candidate pixels in the sub-area; and

designate the average thickness of the sub-area corresponding to the one or more candidate pixels in the sub-area as the equivalent thickness of the OOI corresponding to each pixel in the sub-area.

5. The system of claim 1 , wherein to determine, for each pixel of the one or more pixels of the OOI, a scatter correction coefficient of the each pixel based at least in part on the equivalent thickness of the OOI corresponding to the each pixel, the at least one processor is further configured to direct the system to:

obtain a correction template that corresponds to a target equivalent thickness, the target equivalent thickness being the equivalent thickness of the OOI corresponding to the each pixel, the correction template including a plurality of scatter correction coefficients corresponding to a plurality of detector units of the X-ray imaging device; and

designate the scatter correction coefficient of the detector unit acquiring a portion of the scan data that corresponds to the each pixel as the scatter correction coefficient of the each pixel.

6. The system of claim 5 , wherein the correction template that corresponds to the target equivalent thickness is generated according to a correction template generation process comprising:

obtaining photon information related to a scan of a phantom, the photon information being related to a plurality of photons that are detected by the plurality of detector units of the X-ray imaging device during the scan, the phantom having thickness being substantially equal to the target equivalent thickness, the phantom having an attenuation characteristic being substantially equal to an attenuation characteristic of the OOI, the photon information including an incidence angle of each of the plurality of photons on the plurality of detector units and a photon energy of each of the plurality of photons;

identifying, based on the photon information, one or more scattered photons among the plurality of photons; and

determining, based on the photon information and the identified one or more scattered photons, the plurality of scatter correction coefficients corresponding to the plurality of detector units.

7. The system of claim 6 , wherein the correction template corresponding to the target equivalent thickness is generated according to a Monte-Carlo simulation technique.

8. The system of claim 5 , wherein the scan data of the subject is acquired by the X-ray imaging device under a target imaging condition, and

to obtain a correction template corresponding to the target equivalent thickness, the at least one processor is further configured to direct the system to:

obtain a plurality of candidate correction templates corresponding to the target equivalent thickness, each of the candidate correction templates corresponding to an imaging condition; and

select, among the plurality of candidate correction templates, the candidate correction template corresponding to the target imaging condition as the correction template corresponding to the target equivalent thickness.

9. The system of claim 1 , wherein the at least one processor is configured to further direct the system to:

identify a plurality of OOIs from the image, each of the OOI including one or more pixels;

for each OOI of the plurality of OOIs,

determine an equivalent thickness of the each OOI corresponding to each pixel in the each OOI based on a pixel value of the each pixel in the each OOI and the reference image;

determine a scatter correction coefficient of the each pixel in the each OOI based at least in part on the equivalent thickness of the each OOI corresponding to the each pixel in the each OOI; and

correct the pixel value of the each pixel in the each OOI using the corresponding scatter correction coefficient; and

generate a corrected image by combining the plurality of corrected OOIs.

10. The system of claim 1 , wherein a scatter correction coefficient includes at least one of a scatter-to-primary ratio (SPR), a scatter ratio, or a primary ratio.