Method and system for reconstructing image volumes from helical scan acquisitions

A computed tomography (CT) system for reconstructing an image volume of an object scanned in helical mode, the computed tomography system comprising:

• an X-ray source configured to project a plurality of X-ray beams through the object from a plurality of projection angles;
• a detector configured to produce a plurality of electrical signals corresponding to the plurality of X-ray beams;
• and
• a processor configured to process the electrical signals to generate one or more helical views corresponding to the imaged object, wherein the processor is configured to:
• determine a plurality of discrete focal lengths within an imaging plane of a reconstructed field of view comprising the image volume;
• generate a plurality of circular scan sinograms for the plurality of discrete focal lengths, wherein the plurality of circular scan sinograms are generated by interpolating the one or more helical views;
• select one or more circular scan sinograms from the plurality of circular scan sinograms, based on the plurality of discrete focal lengths, wherein the selection is performed within a projection operation, for one or more image points within the imaging plane, over one or more circular views;
• and
• use one or more of the selected circular scan sinograms, in the backprojection of one or more of the image points over one or more of the circular views;
• and
• performing a backprojection for the one or more image points, over the one or more circular views to generate a reconstructed image of the object.

A computer-readable medium storing computer instructions for instructing a computer system for reconstructing an image volume of an object scanned in helical mode, the computer instructions comprising:

• obtaining one or more helical views corresponding to an image volume of an object;
• determining a plurality of discrete focal lengths within an imaging plane of a reconstructed field of view comprising the image volume;
• generating a plurality of circular scan sinograms for the plurality of discrete focal lengths, wherein the plurality of circular scan sinograms are generated by interpolating the one or more helical views;
• selecting one or more circular scan sinograms, from the plurality of circular scan sinograms, based on the plurality of discrete focal lengths, wherein the selection is performed within a backprojection operation, for one or more image points within the imaging plane, over one or more circular views;
• using one or more of the selected circular scan sinograms, in the backprojection of one or more of the image points over one or more of the circular views;
• and,
• performing a backprojection for the one or more image points, over the one or more circular views to generate a reconstructed image of the object.