Method and apparatus for reconstruction of 3D image volumes from projection images
First Claim
1. An apparatus for computed tomography of the type that reconstructs density distribution of a volume from a plurality of measured projection images, comprisinga graphics processing unit (GPU) including a plurality of programmable vertex shaders that are coupled to a plurality of programmable pixel shaders,the vertex shaders and the pixel shaders being adapted to generate, for at least one measured projection image, a respective forward-projection image of an estimated density distribution assigned to the volume and to generate one or more correction terms based on comparison of one or more pixels in the forward-projection image with respective pixels in that measured projection image.
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Abstract
The invention provides improvements in reconstructive imaging of the type in which a volume is reconstructed from a series of measured projection images (or other two-dimensional representations) by utilizing the capabilities of graphics processing units (GPUs). In one aspect, the invention configures a GPU to reconstruct a volume by initializing an estimated density distribution of that volume to arbitrary values in a three-dimensional voxel-based matrix and, then, determining the actual density distribution iteratively by, for each of the measured projections, (a) forward-projecting the estimated volume computationally and comparing the forward-projection with the measured projection, (b) generating a correction term for each pixel in the forward-projection based on that comparison, and (c) back-projecting the correction term for each pixel in the forward-projection onto all voxels of the volume that were mapped into that pixel in the forward-projection.
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Citations
16 Claims
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1. An apparatus for computed tomography of the type that reconstructs density distribution of a volume from a plurality of measured projection images, comprising
a graphics processing unit (GPU) including a plurality of programmable vertex shaders that are coupled to a plurality of programmable pixel shaders, the vertex shaders and the pixel shaders being adapted to generate, for at least one measured projection image, a respective forward-projection image of an estimated density distribution assigned to the volume and to generate one or more correction terms based on comparison of one or more pixels in the forward-projection image with respective pixels in that measured projection image.
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3. An apparatus for computed tomography of the type that reconstructs density distribution of a volume from a plurality of measured projection images, comprising
a graphics processing unit (GPU) including a plurality of programmable vertex shaders that are coupled to a plurality of programmable pixel shaders, the vertex shaders and the pixel shaders being adapted to generate for at least one measured projection image a respective forward-projection image of an estimated density distribution assigned to the volume and to generate one or more correction terms based on comparison of one or more pixels in the forward-projection image with respective pixels in that measured projection image; -
wherein the volume is represented as a plurality of slices, and wherein one or more of the vertex shaders are configured to map to each pixel in the forward-projection image a plurality of voxels that lie substantially at vertices of one or more selected polygonal portions of the slices. - View Dependent Claims (4, 5, 6, 7, 8, 9, 13, 14, 15, 16)
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Specification