System and method for providing normalization correction for image reconstruction in a reduced pitch spiral scan cone beam computed tomography imaging system
First Claim
1. A method for image reconstruction in a spiral scan imaging system, comprising the steps of:
- acquiring cone beam projection data for a 1/n reduced-pitch spiral scan of a ROI (region of interest) of an object, wherein the step of acquiring comprises applying radiation from a cone beam source towards the object from a plurality of source positions along the 1/n reduced-pitch spiral scan path that encircles the ROI, and acquiring a set of cone beam projection data on an area detector, the set of cone beam data corresponding to a respective portion of the ROI at each of said source positions;
identifying a set of integration planes that intersect the ROI and that intersect the 1/n reduced-pitch spiral scan path at M<
n locations;
computing a contribution of cone beam image data for the identified set of integration planes;
computing a correction factor for the identified set of integration planes and adding the correction factor to the cone beam image data associated with the identified set of integration planes so as to increase the S/N (signal-to-noise) ratio;
reconstructing an image of the ROI using the corrected cone beam image data.
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Abstract
A system and method for 3D image reconstruction in a spiral scan cone beam computed tomography (CT) imaging system that allows the pitch of spiral scan projection to be reduced by a factor of 1/n (where n=3, 5, 7, 9, etc), thereby increasing the x-ray dosage to obtain a higher S/N (signal-to-noise) ratio, while achieving efficient use of a fixed-size detector. In addition, an image reconstruction protocol computes a correction factor for integration planes that intersect the reduced-pitch spiral path (which surrounds a ROI) at only M<n locations within an angular range that is determined, e.g., for M=1 planes, based on mask boundaries applied to the cone beam data. Despite the reduced pitch, the M<n integration planes do not provide increased flux (in contrast to other integration planes that intersect the object and scan path in M∃n locations).
33 Citations
16 Claims
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1. A method for image reconstruction in a spiral scan imaging system, comprising the steps of:
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acquiring cone beam projection data for a 1/n reduced-pitch spiral scan of a ROI (region of interest) of an object, wherein the step of acquiring comprises applying radiation from a cone beam source towards the object from a plurality of source positions along the 1/n reduced-pitch spiral scan path that encircles the ROI, and acquiring a set of cone beam projection data on an area detector, the set of cone beam data corresponding to a respective portion of the ROI at each of said source positions;
identifying a set of integration planes that intersect the ROI and that intersect the 1/n reduced-pitch spiral scan path at M<
n locations;
computing a contribution of cone beam image data for the identified set of integration planes;
computing a correction factor for the identified set of integration planes and adding the correction factor to the cone beam image data associated with the identified set of integration planes so as to increase the S/N (signal-to-noise) ratio;
reconstructing an image of the ROI using the corrected cone beam image data. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A program storage device readable by a machine, tangibly embodying a program of instructions executable by the machine to perform method steps for image reconstruction in a spiral scan imaging system, the method steps comprising:
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acquiring cone beam projection data for a 1/n reduced-pitch spiral scan of a ROI (region of interest) of an object, wherein the step of acquiring comprises applying radiation from a cone beam source towards the object from a plurality of source positions along the reduced-pitch spiral scan path that encircles the ROI, and acquiring a set of cone beam projection data on an area detector, the set of cone beam data corresponding to a respective portion of the ROI at each of said source positions;
identifying a set of integration planes that intersect the ROI and that intersect the reduced-pitch spiral scan path at M<
n locations;
computing a contribution of cone beam image data for the identified set of integration planes;
computing a correction factor for the identified set of integration planes and adding the correction factor to the cone beam image data associated with the identified set of integration planes so as to increase the S/N (signal-to-noise) ratio;
reconstructing an image of the ROI using, in part, the corrected cone beam image data. - View Dependent Claims (10, 11, 12, 13, 14, 15, 16)
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Specification