Mask boundary correction in a cone beam imaging system using simplified filtered backprojection image reconstruction
First Claim
1. A scanning and data acquisition method for three dimensional (3D) computerized tomographic (CT) imaging of a region-of-interest (ROI) in an object, wherein image reconstruction processing is applied to a plurality of sets of 2D cone beam projection data, each set being acquired by irradiation of the object by energy from a cone beam source that is directed to a 2D detector at a corresponding plurality of scan path source positions, comprising the steps of:
- applying a mask to each set of the projection data so that data inside the boundaries of each mask form a corresponding plurality of masked 2D data sets;
ramp filtering each masked 2D data set along a plurality of parallel lines formed therein, to generate a corresponding plurality of filtered 2D data, each filtered 2D data set corresponding to a calculation of a first estimate of Radon derivative data determined from a given set of the 2D cone beam projection data;
developing 2D correction data for each of the first estimates of Radon derivative data by processing portions of the given set of cone beam projection data that are adjacent boundaries of the mask; and
combining each filtered 2D data set and the 2D correction data calculated therefore, in a weighted 3D backprojection manner into a 3D space, thereby reconstructing 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 tomographic (CT) imaging of a region-of-interest (ROI) in an object, wherein image reconstruction processing is applied to a plurality of sets of 2D cone beam projection data, each set being acquired on a 2D 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 so that data inside the boundaries of each mask form a corresponding plurality of masked 2D data sets. The next step comprises ramp filtering of each masked 2D data set along a plurality of parallel lines formed therein, to generate a corresponding plurality of filtered 2D data sets. Each filtered 2D data set is a calculation of a first estimate of Radon derivative data determined from a given set of the 2D cone beam projection data. The next step comprises developing 2D correction data for each of the first estimates of Radon derivative data by processing portions of the given set of cone beam projection data that are adjacent boundaries of the mask. The final step comprises combining each filtered 2D data set and the 2D correction data calculated therefore, in a weighted 3D backprojection manner into a 3D space, thereby reconstructing a 3D image of the ROI in the object.
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Citations
24 Claims
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1. A scanning and data acquisition method for three dimensional (3D) computerized tomographic (CT) imaging of a region-of-interest (ROI) in an object, wherein image reconstruction processing is applied to a plurality of sets of 2D cone beam projection data, each set being acquired by irradiation of the object by energy from a cone beam source that is directed to a 2D detector at a corresponding plurality of scan path source positions, comprising the steps of:
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applying a mask to each set of the projection data so that data inside the boundaries of each mask form a corresponding plurality of masked 2D data sets; ramp filtering each masked 2D data set along a plurality of parallel lines formed therein, to generate a corresponding plurality of filtered 2D data, each filtered 2D data set corresponding to a calculation of a first estimate of Radon derivative data determined from a given set of the 2D cone beam projection data; developing 2D correction data for each of the first estimates of Radon derivative data by processing portions of the given set of cone beam projection data that are adjacent boundaries of the mask; and combining each filtered 2D data set and the 2D correction data calculated therefore, in a weighted 3D backprojection manner into a 3D space, thereby reconstructing a 3D image of the ROI in the object. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15)
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16. Apparatus for three dimensional (3D) computerized tomographic (CT) imaging of a region-of-interest (ROI) in an object, comprising:
- a cone beam source for applying radiation energy to at least the ROI of the object;
a 2D 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 2D cone beam projection data at each of said source positions; a masking means for applying a mask to each set of the 2D cone beam projection data to generate masked data sets; a ramp filtering means for ramp filtering each masked 2D data set along a plurality of parallel lines formed therein, to generate a corresponding plurality of filtered 2D data, each filtered 2D data set corresponding to a calculation of a first estimate of Radon derivative data determined from a given set of the 2D cone beam projection data; processing means for developing 2D correction data for each of the first estimates of Radon derivative data by processing portions of the given set of 2D cone beam projection data that are adjacent boundaries of the mask; and 3D backprojection means for combining each filtered 2D data set and the 2D correction data calculated therefore, in a weighted 3D backprojection manner into a 3D space, thereby reconstructing a 3D image of the ROI in the object. - View Dependent Claims (17, 18, 19, 20, 21, 22, 23, 24)
- a cone beam source for applying radiation energy to at least the ROI of the object;
Specification