Computed tomography scanning apparatus and method for generating parallel projections using non-parallel slice data
First Claim
1. A method of generating a two-dimensional projection image of an object in a region having a longitudinal axis, said method comprising:
- scanning the region to generate scan data representative of the region, said scanning comprising;
providing a radiation source and an array of detectors on opposed sides of the region,rotating at least the radiation source about the longitudinal axis while the radiation source emits radiation toward the array of detectors, andwith the array of detectors, receiving radiation from the region to generate the scan data for the region;
defining a plurality of image data slices corresponding to a plurality of positions along the longitudinal axis of the region, successive image data slices being non-parallel with each other, each of said image data slices defining a plurality of scan data projections obtained from a respective plurality of view angles during the scanning step, each scan data projection containing scan data at its respective view angle;
selecting a projection angle for the two-dimensional projection image of the region;
for each of said image data slices, identifying the view angle that corresponds to the selected projection angle;
for each of said image data slices, selecting the scan data projection that corresponds to the identified view angle; and
generating the two-dimensional projection image of the region using the selected scan data projections.
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Abstract
A nutating slice CT image reconstruction apparatus and method generates a set of projection data using helical cone-beam scanning. The three-dimensional projection data is used to reconstruct a series of planar image slices. The slices are selected such that they define a tilt angle and a rotation angle with respect to the longitudinal axes of the object being scanned. Successive slices have equal tilt angles but changing rotation angles such that normal axes of successive slices define a nutation and precession about the longitudinal axis of the object. Projection data for the tilted slices are formed of selected one-dimensional fan-beam data. As such, the projection data can be applied to conventional two-dimensional reconstruction approaches to generate an image. The projection data can also be used to generate two-dimensional projection images at one or more stationary projection angles through an object being scanned. The nutation or tilt of image volume elements can be compensated for to provide a more accurate image and more accurate target assessment such as accurate total mass determination. A parallel processing architecture can be used to generate and process the nutated slices with improved efficiency.
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Citations
22 Claims
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1. A method of generating a two-dimensional projection image of an object in a region having a longitudinal axis, said method comprising:
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scanning the region to generate scan data representative of the region, said scanning comprising; providing a radiation source and an array of detectors on opposed sides of the region, rotating at least the radiation source about the longitudinal axis while the radiation source emits radiation toward the array of detectors, and with the array of detectors, receiving radiation from the region to generate the scan data for the region; defining a plurality of image data slices corresponding to a plurality of positions along the longitudinal axis of the region, successive image data slices being non-parallel with each other, each of said image data slices defining a plurality of scan data projections obtained from a respective plurality of view angles during the scanning step, each scan data projection containing scan data at its respective view angle; selecting a projection angle for the two-dimensional projection image of the region; for each of said image data slices, identifying the view angle that corresponds to the selected projection angle; for each of said image data slices, selecting the scan data projection that corresponds to the identified view angle; and generating the two-dimensional projection image of the region using the selected scan data projections. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13)
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14. An apparatus for generating a two-dimensional projection image of an object in a region having a longitudinal axis, said apparatus comprising:
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a radiation source and an array of detectors on opposed sides of the region, said radiation source being mounted on a rotatable member rotatable about the longitudinal axis of the region while the radiation source emits radiation toward the array of detectors, said array of detectors receiving radiation from the region to generate scan data for the region; means for defining a plurality of image data slices corresponding to a plurality of positions along the longitudinal axis of the region, successive image data slices being non-parallel with each other, each of said image data slices defining a plurality of scan data projections obtained from a respective plurality of view angles during the scanning step, each scan data projection containing scan data at its respective view angle; means for selecting a projection angle for the two-dimensional projection image of the region; means for identifying, for each of said image data slices, the view angle that corresponds to the selected projection angle; means for selecting, for each of said image data slices, the scan data projection that corresponds to the identified view angle; and means for generating the two-dimensional projection image of the region using the selected scan data projections. - View Dependent Claims (15, 16, 17, 18, 19, 20, 21, 22)
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Specification