Localized motion artifact reduction in projection imaging

Claim 1

A method for producing an image of a moving patient composed of a plurality of voxels, each voxel having reference coordinate defined at a reference time while the patient is in motion, and a displaced coordinate which at the reference time may equal the reference coordinate, but at other times may not equal the reference coordinate, the steps comprising: performing a scan in which a plurality of projections of a projection data set are acquired at different times and throughout a range of different projection angles (θ), each projection measuring physical characteristic of the voxels at their displaced coordinates; acquiring a motion parameter with each projection of the projection set, each acquired motion parameter being indicative of the movement of the patient as the projection set is acquired; and back projecting the set of projections to produce the image of the patient using a back projection formula which is modified to account for the displacement of the voxels from their reference coordinates at the time of the projection is acquired, the modification being according to a predetermined warping function that relates the displaced coordinates of the voxels to their reference coordinates as a function of the motion parameter; whereby artifacts produced in the image by movement of the patient from projection-to-projection during the scan are reduced.

Claim 2

A method for producing an image of a moving patient composed of a plurality of voxels, each voxel having reference coordinate defined at a reference time while the patient is in motion, and a displaced coordinate which at the reference time may equal the reference coordinate, but at other times may not equal the reference coordinate, the steps comprising: performing a scan in which a plurality of projections of a projection data set are acquired at different times and throughout a range of different projection angles (θ), each projection measuring physical characteristic of the voxels at their displaced coordinates; acquiring a motion parameter with each projection of the projection set, each acquired motion parameter being indicative of the movement of the patient as the projection set is acquired; and back projecting the set of projections to produce the image of the patient using a back projection formula which is modified to account for the displacement of the voxels from their reference coordinates at the time of the projection is acquired, the modification being according to a predetermined warping function that relates the displaced coordinates of the voxels to their reference coordinates as a function of the motion parameter; whereby artifacts produced in the image by movement of the patient from projection-to-projection during the scan are reduced.