Systems and methods for improving a resolution of an image

A tomographic imaging system comprising:

• an X-ray source configured to generate a beam of radiation;
• a detector array configured to receive the beam of radiation;
• and
• an image reconstructor in communication with said X-ray source and said detector array for receiving image data, said image reconstructor configured to:
• generate a first estimate of the image;
• generate a second estimate of the image after generating the first estimate of the image;
• compare actual projection data and expected projection data of the second estimate of the image;
• adjust the first estimate using the comparison;
• generate a virtual X-ray source corresponding to a real X-ray source of the tomographic imaging system;
• generate a virtual X-ray detector plane including a plurality of virtual detector elements corresponding to a real X-ray detector array of the tomographic imaging system, the real X-ray detector array including a plurality of detector cells to which the plurality of virtual detector elements correspond;
• determine image volume data that includes a value representing an X-ray density of an image voxel using the virtual X-ray source and the virtual X-ray detector;
• and
• adjust the first estimate by:
• applying a forward projection function to the image voxel to generate a forward projection region that includes at least one virtual detector element of the virtual detector plane;
• determining a set of the virtual detector elements that contribute to a resolution of the image voxel by forward projecting the image voxel on to the virtual detector plane at a projection angle from the virtual X-ray source;
• adjusting a size of one of the virtual detector elements to be one of larger and smaller than a corresponding one of the detector cells of the real X-ray detector array;
• determining a plurality of values of a set of the virtual detector elements that are within the virtual detector plane and that are used to reconstruct the image volume data;
• assigning a first weight to a first portion of the actual projection data and a first forward projection function, wherein the first portion of the actual projection data and the first forward projection function are generated when the virtual X-ray source is at a first position and are used to reconstruct the image voxel;
• and
• assigning a second weight to a second portion of the actual projection data and a second forward projection function, wherein the second portion of the actual projection data and the second forward projection function are generated when the virtual X-ray source is at a second position and are used to reconstruct the image voxel, the second weight being lower than the first weight, and the first position being closer to the image voxel than the second position is to the image voxel;
• and
• output the image based on the adjusted first estimate of the image, the output image having a higher resolution than a resolution of the first estimate.

A method for reconstructing an image using a tomographic imaging system, said method comprising:

• generating a first estimate of the image across a field-of-view;
• generating a second estimate of the image across the field-of-view after generating the first estimate of the image;
• comparing actual projection data and expected projection data of the second estimate of the image;
• adjusting the first estimate using the comparison of the second estimate to generate a third estimate of the image across the field-of-view;
• generating a fourth estimate of the image across the field-of-view after adjusting the first estimate to generate the third estimate;
• comparing the actual projection data and expected projection data of the fourth estimate of the image;
• adjusting the third estimate using the comparison of the fourth estimate to generate a fifth estimate of the image across the field-of-view;
• and
• outputting the image based on the fifth estimate of the image, the output image having a higher resolution than a resolution of the first estimate.