Cone beam CT apparatus using truncated projections and a previously acquired 3D CT image
First Claim
1. An apparatus for reconstructing a 3D image of at least a first region of an object from truncated cone beam projection data acquired by means of an x-ray device having a source-detector assembly moved along an acquisition trajectory such that a cone beam between the source and the detector encompasses said first region, the apparatus comprising:
- extrapolation means for processing the truncated projection data to derive pseudo-projection data associated with projection directions outside the detector;
first 3D reconstruction means for reconstructing an intermediate CT image covering at least the first region of the object based on the truncated projection data completed with the pseudo-projection data;
registration means for computing registration data representing a spatial transformation selected to register a prior CT image, representing a second region of the object including the first region and larger than the first region, with the intermediate CT image;
forward projection means for processing the truncated projection data and the registered prior CT image to derive forward projection data associated with projection directions outside the detector; and
second 3D reconstruction means for synthesizing a reconstructed CT image covering at least the first region of the object based on the truncated projection data completed with the forward projection data.
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Accused Products
Abstract
A 3D image of a region of an object is computed from truncated cone beam projection data acquired with an x-ray device and a prior CT image representing a larger region of the object. The truncated projection data are extrapolated to derive pseudoprojection data associated with projection directions outside the detector, and an intermediate CT image is reconstructed based on the truncated projection data completed with the pseudoprojection data. The prior CT image is then registered with the intermediate CT image. Forward projection data associated with projection directions outside the detector are computed from the truncated projection data and the registered prior CT image. The 3D image is finally reconstructed based on the truncated projection data completed with the forward projection data.
30 Citations
13 Claims
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1. An apparatus for reconstructing a 3D image of at least a first region of an object from truncated cone beam projection data acquired by means of an x-ray device having a source-detector assembly moved along an acquisition trajectory such that a cone beam between the source and the detector encompasses said first region, the apparatus comprising:
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extrapolation means for processing the truncated projection data to derive pseudo-projection data associated with projection directions outside the detector; first 3D reconstruction means for reconstructing an intermediate CT image covering at least the first region of the object based on the truncated projection data completed with the pseudo-projection data; registration means for computing registration data representing a spatial transformation selected to register a prior CT image, representing a second region of the object including the first region and larger than the first region, with the intermediate CT image; forward projection means for processing the truncated projection data and the registered prior CT image to derive forward projection data associated with projection directions outside the detector; and second 3D reconstruction means for synthesizing a reconstructed CT image covering at least the first region of the object based on the truncated projection data completed with the forward projection data. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A computer readable storage medium containing instructions which, when executed by a computer for reconstructing a 3D image of at least a first region of an object from truncated cone beam projection data acquired by means of an x-ray device having a source-detector assembly moved along an acquisition trajectory such that a cone beam between the source and the detector encompasses said first region, cause the computer to perform the step of:
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extrapolating the truncated projection data to derive pseudo-projection data associated with projection directions outside the detector; reconstructing an intermediate 3D CT image covering at least the first region of the object based on the truncated projection data completed with the pseudo-projection data; registering a prior CT image, representing a second region of the object including the first region and larger than the first region, with the intermediate CT image; processing the truncated projection data and the registered prior CT image to derive forward projection data associated with projection directions outside the detector; and synthesizing a reconstructed CT image covering at least the first region of the object based on the truncated projection data completed with the forward projection data. - View Dependent Claims (9, 10, 11, 12, 13)
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Specification