Methods and apparatus for FOV-dependent aliasing artifact reduction
First Claim
1. A method for reducing aliasing artifacts in a computed tomography system, said method comprising:
- scanning an object with a computed tomography system to acquire a projection data set of measured views;
synthesizing additional views of the projection data set utilizing view interpolation; and
filtering and backprojecting the projection data set utilizing a weighting function dependent upon parameters Rf and Rt, where radius Rf around an isocenter of the CT imaging system is selected in accordance with a low artifact criterion and Rt is a parameter defining a transition region outside of radius Rf around the isocenter of the CT imaging system.
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Abstract
In one aspect, there is provided a method for reducing aliasing artifacts in a computed tomography system. The method includes scanning an object with a computed tomography system to acquire a projection data set of measured views; synthesizing additional views of the projection data set utilizing view interpolation; and filtering and backprojecting the projection data set utilizing a weighting function dependent upon parameters Rf and Rt, where radius Rf around an isocenter of the CT imaging system is selected in accordance with a low artifact criterion and Rt is a parameter defining a transition region outside of radius Rf around the isocenter of the CT imaging system.
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Citations
40 Claims
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1. A method for reducing aliasing artifacts in a computed tomography system, said method comprising:
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scanning an object with a computed tomography system to acquire a projection data set of measured views;
synthesizing additional views of the projection data set utilizing view interpolation; and
filtering and backprojecting the projection data set utilizing a weighting function dependent upon parameters Rf and Rt, where radius Rf around an isocenter of the CT imaging system is selected in accordance with a low artifact criterion and Rt is a parameter defining a transition region outside of radius Rf around the isocenter of the CT imaging system. - View Dependent Claims (2)
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3. A method for reducing aliasing artifacts in a computed tomography system, said method comprising:
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scanning an object with a computed tomography (CT) imaging system to acquire a projection data set of measured views;
reconstructing a first image utilizing the measured views to produce an image having a central, essentially artifact-free zone;
interpolating views between measured views to produce a projection data set having interpolated views;
reconstructing a second image utilizing both the interpolated views and the measured views; and
producing a blended image from the first image and the second image utilizing a weighting function selected to smoothly transition from the first image to the second image in a transition region surrounding an isocenter of the CT imaging system. - View Dependent Claims (4, 5, 6, 7, 8)
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9. A method for reducing aliasing artifacts in a computed tomography system, said method comprising:
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scanning an object with a computed tomography (CT) imaging system to acquire a projection data set of measured views;
reconstructing a first image utilizing the projection data of measured views set to produce an image having a central, essentially artifact-free zone;
interpolating views between the measured views to produce a projection data set having interpolated views;
reconstructing a second image utilizing the interpolated views; and
producing a blended image from the first image and the second image utilizing a weighting function selected to smoothly transition from the first image to the second image in a transition region surrounding an isocenter of the CT imaging system;
and further wherein the first image is written P1(i, j), the second image is written P2(i, j), pixel (i, j) is a distance r from the isocenter, and images P1(i, j) and P2(i, j) are combined by weighting P1(i, j) and P2(i, j) with weights w1(i, j) and w2 (i, j), respectively, where a sum of weights w1(i, j) and w2 (i, j) is a constant, and w2 (i, j) increases in magnitude relative to w1(i, j) at least within a transition region in a vicinity of a radius Rf of the central, essentially artifact-free zone. - View Dependent Claims (10)
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11. A computed tomographic (CT) imaging system having a rotating gantry, a detector array on said rotating gantry, and a radiation source on said rotating gantry configured to project a beam of radiation towards said detector array through an object to be imaged;
said system configured to;
scan an object to acquire a projection data set of measured views;
synthesize additional views of said projection data set utilizing view interpolation; and
filter and backproject said projection data set utilizing a weighting function dependent upon parameters Rf and Rt, where radius Rf around an isocenter of said CT imaging system is selected in accordance with a low artifact criterion and Rt is a parameter defining a transition region outside of radius Rf around said isocenter of said CT imaging system. - View Dependent Claims (12)
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13. A computed tomographic (CT) imaging system having a rotating gantry, a detector array on said rotating gantry, and a radiation source on said rotating gantry configured to project a beam of radiation towards said detector array through an object to be imaged;
said system configured to;
scan an object to acquire a projection data set of measured views;
reconstruct a first image utilizing said measured views to produce an image having a central, essentially artifact-free zone;
interpolate views between measured views to produce a projection data set having both interpolated views and said measured views;
reconstruct a second image utilizing both said interpolated views and said measured views; and
produce a blended image from said first image and said second image utilizing a weighting function selected to smoothly transition from said first image to said second image in a transition region surrounding an isocenter of said CT imaging system. - View Dependent Claims (14, 15, 16, 17, 18)
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19. A computed tomographic (CT) imaging system having a rotating gantry, a detector array on said rotating gantry, and a radiation source on said rotating gantry configured to project a beam of radiation towards said detector array through an object to be imaged;
said system configured to;
scan an object to acquire a projection data set of measured views;
reconstruct a first image utilizing said measured views to produce an image having a central, essentially artifact-free zone;
interpolate views between said measured views to produce a projection data set of interpolated views;
reconstruct a second image utilizing said interpolated views; and
produce a blended image from said first image and said second image utilizing a weighting function selected to smoothly transition from said first image to said second image in a transition region surrounding an isocenter of said CT imaging system;
and further wherein said first image is written P1(i, j), said second image is written P2(i, j), pixel (i, j) is a distance r from said isocenter, and said system is configured to combine said images P1(i, j) and P2(i, j) by weighting P1(i, j) and P2(i, j) with weights w1(i, j) and w2 (i, j), respectively, where a sum of said weights w1(i, j) and w2(i, j) is a constant, and w2 (i, j) increases in magnitude relative to w1(i, j) at least within a transition region in a vicinity of a radius Rf of said central, essentially artifact-free zone. - View Dependent Claims (20)
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21. A computer configured to:
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read a projection data set of measured views obtained by scanning an object with a computed tomographic (CT) imaging system;
synthesize additional views of the projection data set utilizing view interpolation; and
filter and backproject the projection data set utilizing a weighting function dependent upon parameters Rf and Rt, where radius Rf around an isocenter of the CT imaging system is selected in accordance with a low artifact criterion and Rt is a parameter defining a transition region outside of radius Rf around the isocenter of said CT imaging system. - View Dependent Claims (22)
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23. A computer configured to:
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read a projection data set of measured views obtained by scanning an object with a computed tomographic imaging system;
reconstruct a first image utilizing the measured views to produce an image having a central, essentially artifact-free zone;
interpolate views between the measured views to produce a projection data set having interpolated views;
reconstruct a second image utilizing said interpolated views; and
produce a blended image from said first image and said second image utilizing a weighting function selected to smoothly transition from said first image to said second image in a transition region surrounding an isocenter of the CT imaging system. - View Dependent Claims (24, 25, 26, 27, 28, 29, 30)
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31. A computer readable medium having instructions recorded thereon configured to instruct a computer to:
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read a projection data set of measured views obtained by scanning an object with a computed tomographic (CT) imaging system;
synthesize additional views of the projection data set utilizing view interpolation; and
filter and backproject the projection data set utilizing a weighting function dependent upon parameters Rf and Rt, where radius Rf around an isocenter of the CT imaging system is selected in accordance with a low artifact criterion and Rt is a parameter defining a transition region outside of radius Rf around the isocenter of said CT imaging system. - View Dependent Claims (32)
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33. A computer readable medium having instructions recorded thereon configured to instruct a computer to:
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read a projection data set of measured views obtained by scanning an object with a computed tomographic imaging system;
reconstruct a first image utilizing the measured views to produce an image having a central, essentially artifact-free zone;
interpolate views between the measured views to produce an projection data set having interpolated views;
reconstruct a second image utilizing said interpolated views; and
produce a blended image from said first image and said second image utilizing a weighting function selected to smoothly transition from said first image to said second image in a transition region surrounding an isocenter of the CT imaging system. - View Dependent Claims (34, 35, 36, 37, 38, 39, 40)
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Specification