Simplified cone beam image reconstruction using 3D backprojection
First Claim
1. A scanning and data acquisition method for three dimensional (3D) computerized tomography (CT) imaging of a region-of-interest (ROI) in an object, comprising the steps of:
- applying radiation energy from a cone beam source to at least the ROI of the object;
defining a source scanning trajectory as a scan path traversed by the source;
using the cone beam source, fixed relative to an area detector with both source and detector movably positioned relative to the object, to scan about the ROI in the object along the scan path;
scanning at a plurality of source positions in a direction along the scan path to cause said area detector to acquire a set of cone beam projection data at each of said source positions;
applying a mask to each set of the projection data to form masked data sets;
convolution processing each masked data set along a plurality of parallel lines formed therein that are parallel with and in the direction of a parallel projection into the data set of a line that is tangent to the scan path at the source position that acquired that data set and in the direction of scanning, to generate filtered data sets;
subjecting the data of each filtered data set to a weighted 3D backprojection into a 3D space, thereby reconstructing in a piecewise manner a 3D image of the ROI in the object.
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Abstract
A scanning and data acquisition method and apparatus for three dimensional (3D) computerized tomography (CT) imaging of a region-of-interest (ROI) in an object, wherein image reconstruction processing is applied to a plurality of sets of cone beam projection data, each set being acquired on a detector at a corresponding plurality of scan path source positions. A first image reconstruction processing step comprises applying a mask to each set of the projection data to form masked data sets. The mask for each data set is formed by cone beam projections onto the plane of the detector of portions of the source scan path that are above and below the source position that acquired the data set being masked. The next image reconstruction processing step comprises ramp filtering of each masked data set along a plurality of parallel lines formed therein that are parallel with and in the direction of a parallel projection into the data set of a line that is tangent to the scan path at the source position that acquired that data set and in the direction of the next source position, to generate filtered data sets. Each filtered data set is then subjected to a weighted 3D backprojection into a 3D space, thereby reconstructing in a piecewise manner a 3D image of the ROI in the object.
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Citations
25 Claims
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1. A scanning and data acquisition method for three dimensional (3D) computerized tomography (CT) imaging of a region-of-interest (ROI) in an object, comprising the steps of:
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applying radiation energy from a cone beam source to at least the ROI of the object; defining a source scanning trajectory as a scan path traversed by the source; using the cone beam source, fixed relative to an area detector with both source and detector movably positioned relative to the object, to scan about the ROI in the object along the scan path; scanning at a plurality of source positions in a direction along the scan path to cause said area detector to acquire a set of cone beam projection data at each of said source positions; applying a mask to each set of the projection data to form masked data sets; convolution processing each masked data set along a plurality of parallel lines formed therein that are parallel with and in the direction of a parallel projection into the data set of a line that is tangent to the scan path at the source position that acquired that data set and in the direction of scanning, to generate filtered data sets; subjecting the data of each filtered data set to a weighted 3D backprojection into a 3D space, thereby reconstructing in a piecewise manner a 3D image of the ROI in the object. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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- 12. The method of claim I 1, wherein the 3D object volume corresponds to the ROI volume in the object that is scanned by the cone beam source.
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14. Apparatus for three dimensional (3D) computerized tomography (CT) imaging of a region-of-interest (ROI) in an object, comprising:
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a cone beam source for applying radiation energy to at least the ROI of the object; an area detector for detecting radiation energy; means for defining a source scanning trajectory as a scan path traversed by the source; a manipulator for causing the cone beam source, fixed relative to an area detector with both source and detector movably positioned relative to the object, to scan about the ROI in the object at a plurality of source positions in a direction along the scan path to cause said area detector to acquire a set of cone beam projection data at each of said source positions; a masking means for applying a mask to each set of the projection data to generate masked data sets; a convolution processing means for convolution processing each masked data set along a plurality of parallel lines formed therein that are parallel with and in the direction of a parallel projection into the data set of a line that is tangent to the scan path at the source position that acquired that data set and in the direction of scanning, to generate filtered data sets; and 3D backprojection means for subjecting the data of each filtered data set to a weighted 3D backprojection into a 3D space, thereby reconstructing in a piecewise manner a 3D image of the ROI in the object. - View Dependent Claims (15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25)
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Specification