Methods and apparatus for artifact reduction in computed tomography imaging systems
First Claim
1. A method for reconstructing an image of an object of a computed tomographic imaging system having a detector array and a radiation source, wherein an arc of the detector array is not concentric to a focal spot of the radiation source, said method comprising:
- scanning the object with the computed tomographic imaging system to obtain a projection dataset;
performing a geometric correction of the projection dataset according to a corrected fan angle; and
reconstructing an image utilizing the corrected projection dataset.
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Abstract
Some configurations of the present invention provide a method for reconstructing an image of an object of a computed tomographic imaging system having a detector array and a radiation source, wherein an arc of the detector array is not concentric to a focal spot of the radiation source. The method includes scanning the object with the computed tomographic imaging system to obtain a fan beam dataset, rebinning the fan beam dataset into a set of parallel datasets; and reconstructing an image utilizing the set of parallel datasets.
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Citations
28 Claims
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1. A method for reconstructing an image of an object of a computed tomographic imaging system having a detector array and a radiation source, wherein an arc of the detector array is not concentric to a focal spot of the radiation source, said method comprising:
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scanning the object with the computed tomographic imaging system to obtain a projection dataset; performing a geometric correction of the projection dataset according to a corrected fan angle; and reconstructing an image utilizing the corrected projection dataset. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A method for reconstructing an image of an object of a computed tomographic imaging system having a detector array and a radiation source, wherein an arc of the detector array is not concentric to a focal spot of the radiation source, said method comprising:
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scanning the object with the computed tomographic imaging system to obtain a projection dataset; rebinning the projection dataset into a set of parallel datasets including interpolating a sinogram along a line defined by a relationship written as;
β
=β
0−
γ
′
,where;
and β
0 is an angle of an isoray of a radiation beam from the radiation source, γ
is a detector fan angle, β
0 is a projection angle, R is a radiation source to detector element distance in an original geometry in which an arc of the detector array is concentric to a focal spot of the radiation source, and Δ
s and Δ
d are distances that the radiation source and the detector element are from their respective positions in the original geometry, respectively;resampling the parallel datasets so that the datasets are uniformly spaced; and reconstructing an image utilizing the set of resampled parallel datasets. - View Dependent Claims (10, 11, 12)
where t is the distance of a ray to the isocenter, r is the distance of the radiation source to the isocenter distance in an original geometry in which an arc of the detector array is concentric to a focal spot of the radiation source.
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12. A method in accordance with claim 11 further comprising determining a detector array index s utilizing said distance t in accordance with a relationship written as:
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where Δ
γ
is a fan angle between adjacent detector elements in the original geometry.
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13. A method for reconstructing an image of an object of a computed tomographic imaging system having a detector array and a radiation source, wherein an arc of the detector array is not concentric to a focal spot of the radiation source, said method comprising:
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scanning the object using step-and-shoot scanning with the computed tomographic imaging system, without applying a weighting function, to obtain a projection dataset; rebinning the projection dataset into a set of parallel datasets; and reconstructing an image utilizing the set of parallel datasets.
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14. A method for reconstructing an image of an object of a computed tomographic imaging system having a detector array and a radiation source, wherein an arc of the detector array is not concentric to a focal spot of the radiation source, said method comprising:
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scanning the object with the computed tomographic imaging system using helical or halfscan acquisition to obtain a projection dataset; weighting the projection dataset in accordance with a weighting function w′
, derived from a weighting function w for an original geometry in which the arc of the detector array is concentric to the focal spot of the radiation source, wherein
w′
=w(γ
′
, β
, n)and wherein γ
is a detector fan angle, β
is a projection angle, R is a radiation source to detector element distance in the original geometry, and Δ
s and Δ
d are distances that the radiation source and the detector element are from their respective positions in the original geometry, respectively;rebinning the projection dataset into a set of parallel datasets; and reconstructing an image utilizing the set of parallel datasets.
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15. A computed tomography imaging system having a detector array and an radiation source, wherein an arc of the detector array is not concentric to a focal spot of the radiation source, said imaging system configured to:
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scan an object to obtain a projection dataset; perform a geometric correction of the projection dataset according to a corrected fan angle; and reconstruct an image utilizing the corrected projection dataset. - View Dependent Claims (16, 17, 18, 19, 20, 21, 22)
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23. A computed tomography imaging system having a detector array and a radiation source, wherein an arc of the detector array is not concentric to a focal spot of the radiation source, said imaging system configured to:
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scan the object to obtain a projection dataset; rebin the projection dataset into a set of parallel datasets including interpolating a sinogram along a line defined by a relationship written as;
β
=β
0−
γ
′
,where;
and β
0 is an angle of an isoray of a radiation beam from the radiation source, γ
is a detector fan angle, β
is a projection angle, R is a radiation source to detector element distance in an original geometry in which an arc of the detector array is concentric to a focal spot of the radiation source, and Δ
s and Δ
d are distances that the radiation source and the detector element are from their respective positions in the original geometry, respectively;resample the parallel datasets so that the datasets are uniformly spaced; and reconstruct an image utilizing the set of resampled parallel datasets. - View Dependent Claims (24, 25, 26)
where t is the distance of a ray to the isocenter, r is the distance of the radiation source to the isocenter distance in an original geometry in which an arc of the detector array is concentric to a focal spot of the radiation source.
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26. A system in accordance with claim 25 further configured to determine a detector array index s utilizing said distance t in accordance with a relationship written as:
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where Δ
γ
is a fan angle between adjacent detector elements in the original geometry.
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27. A computed tomography imaging system having a detector array and a radiation source, wherein an arc of the detector array is not concentric to a focal spot of the radiation source, said imaging system configured to:
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scan the object using step-and-shoot scanning without applying a weighting function to obtain a projection dataset; rebin the projection dataset into a set of parallel datasets; and reconstruct an image utilizing the set of parallel datasets.
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28. A computed tomography imaging system having a detector array and a radiation source, wherein an arc of the detector array is not concentric to a focal spot of the radiation source, said imaging system configured to:
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scan the object using helical or halfscan acquisition to obtain a projection dataset; weight the projection dataset in accordance with a weighting function w′
, derived from a weighting function w for an original geometry in which the arc of the detector array is concentric to the focal spot of the radiation source, wherein
w′
=w(γ
′
, β
, n)and wherein γ
is a detector fan angle, β
is a projection angle, R is a radiation source to detector element distance in the original geometry, and Δ
s, and Δ
d are distances that the radiation source and the detector element are from their respective positions in the original geometry, respectively;rebin the projection dataset into a set of parallel datasets; and reconstruct an image utilizing the set of parallel datasets.
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Specification