X-ray or gamma ray systems or devices – Specific application – Computerized tomography
Reexamination Certificate
2002-06-29
2003-11-25
Bruce, David V. (Department: 2882)
X-ray or gamma ray systems or devices
Specific application
Computerized tomography
C378S019000, C378S901000
Reexamination Certificate
active
06654440
ABSTRACT:
BACKGROUND OF INVENTION
This invention relates generally to computed tomography (CT) and, more particularly to methods and apparatus for collecting CT scan data.
In at least one known computed tomography (CT) imaging system configuration, an x-ray source projects a divergent, cone-shaped beam. After passing through the sample, the attenuated x-rays are then collected by an array of detectors which, due to the divergent nature of the beam, is much larger than the object being sampled. Such large detector arrays can be expensive. To lower the cost it is desirable to develop a CT scanner system capable of using a smaller detector array yet capable of scanning relatively large samples, such as a patient.
SUMMARY OF INVENTION
In one aspect, a method for collecting computed tomography (CT) scan data is provided. The method includes positioning a gantry at a first position, collecting a partial inverted-cone beam projection at a first detector cell at the first gantry position such that the first detector cell defines a focusing position in space, and collecting data from a second detector cell different from the first detector cell as the gantry rotates such that the focusing position remains substantially stationary in space.
In another aspect, a method for collecting CT scan data is provided. The method includes separating a sampling pattern into a plurality of simplified sampling geometries corresponding to inverted-cone beam trajectories of a plurality of individual detector elements, reconstructing an image volume for each inverted-cone beam trajectory, and combining the reconstructed image volumes into a final image based on a weighted summation of a plurality of the reconstructed image volumes.
In yet another aspect, a method for collecting CT scan data is provided. The method includes collecting x-ray projection samples that arise from x-rays that are perpendicular to the axis of rotation, collecting x-ray projection samples that arise from x-rays that are oblique to the axis of rotation, utilizing the projection samples arising from x-rays perpendicular to the axis of rotation to reconstruct an initial estimate of an object near the object's boundaries, synthesizing a plurality of oblique projections by forward-projection, and combining the synthesized oblique projection samples and the measured oblique projection samples with the initial estimate of the object to produce a complete cone beam reconstruction.
In still another aspect, a method for collecting CT scan data is provided. The method includes positioning a gantry at a first position, collecting a partial cone beam projection from a single source emitter at the first detector position such that the particular emitter defines a focal position in space, switching between a plurality of single source emitters as the gantry rotates so that the focal spot from which radiation emanates is substantially stationary in space, and collecting a partial cone beam from a second emitter at a second detector position.
In another aspect, a method for collecting CT scan data is provided. The method includes positioning a gantry at a first position, collecting an inverted-cone beam projection at a first detector cell at the first gantry position such that the first detector cell defines a focusing position in space, moving the gantry to a second position different from the first such that the source emitters are intermediate between the positions they occupied at the first gantry position, and collecting an inverted-cone beam projection at the second gantry position, at a detector cell that occupies substantially the same point in space defined by the first detector cell during the first data collection cycle.
In yet another aspect, a computer for collecting computed tomography (CT) scan data is provided. The computer is programmed to position a gantry at a first position, collect a partial inverted-cone beam projection at a first detector cell at the first gantry position such that the first detector cell defines a focusing position in space, and collect data from a second detector cell different from the first detector cell as the gantry rotates such that the focusing position remains substantially stationary in space.
In still another aspect, a computer for collecting CT scan data is provided. The computer is programmed to separate a sampling pattern into a plurality of simplified sampling geometries corresponding to inverted-cone beam trajectories of a plurality of individual detector elements, reconstruct an image volume for each inverted-cone beam trajectory, and combine the reconstructed image volumes into a final image based on a weighted summation of a plurality of the reconstructed image volumes.
In another aspect, a computer for collecting CT scan data is provided. The computer is programmed to collect x-ray projection samples that arise from x-rays that are perpendicular to the axis of rotation, collect x-ray projection samples that arise from x-rays that are oblique to the axis of rotation, utilize the projection samples arising from x-rays perpendicular to the axis of rotation to reconstruct an initial estimate of an object near the object's boundaries, synthesize a plurality of oblique projections by forward-projection, and combine the synthesized oblique projection samples and the measured oblique projection samples with the initial estimate of the object to produce a complete cone beam reconstruction.
In yet another aspect, a computer for collecting CT scan data is provided. The computer is programmed to position a gantry at a first position, collect a partial cone beam projection from a single source emitter at the first detector position such that the particular emitter defines a focal position in space, switch between a plurality of single source emitters as the gantry rotates so that the focal spot from which radiation emanates is substantially stationary in space, and collect a partial cone beam from a second emitter at a second detector position.
In another aspect, a computer for collecting CT scan data is provided. The computer is programmed to position a gantry at a first position, collect an inverted-cone beam projection at a first detector cell at the first gantry position such that the first detector cell defines a focusing position in space, move the gantry to a second position different from the first such that the source emitters are intermediate between the positions they occupied at the first gantry position, and collect an inverted-cone beam projection at the second gantry position, at a detector cell that occupies substantially the same point in space defined by the first detector cell during the first data collection cycle.
In still another aspect, a computed tomographic (CT) imaging system for collecting scan data is provided. The CT system includes a two-dimensional x-ray source emitter, a two-dimensional detector array, and a computer coupled to the two-dimensional detector array and the two-dimensional x-ray source emitter. The computer is programmed to position a gantry at a first position, collect a partial inverted-cone beam projection at a first detector cell at the first gantry position such that the first detector cell defines a focusing position in space, and collect data from a second detector cell different from the first detector cell as the gantry rotates such that the focusing position remains substantially stationary in space.
In yet another aspect, a computed tomographic (CT) imaging system for collecting scan data is provided. The CT system includes a two-dimensional x-ray source emitter, a two-dimensional detector array, and a computer coupled to the two-dimensional detector array and the two-dimensional x-ray source emitter. The computer is programmed to separate a sampling pattern into a plurality of simplified sampling geometries corresponding to inverted-cone beam trajectories of a plurality of individual detector elements, reconstruct an image volume for each inverted-cone beam trajectory, and combine the reconstructed image volumes into a final image based on a
Armstrong Teasdale LLP
Bruce David V.
GE Medical Systems Global Technology Company LLC
Horton Esq. Carl B.
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