Reconstruction of images from three-dimensional cone beam data
First Claim
Patent Images
1. A computed tomography imaging system which comprises:
- a two-dimensional array of detector elements for receiving photons emanating in a cone beam from a source;
a digital acquisition system for acquiring two-dimensional arrays of cone beam data from the array of detector elements at a series of views in which the array of detector elements revolves around a central axis;
a filter for receiving the cone beam data and filtering the same;
means for back projecting the filtered cone beam data to produce image data fd({right arrow over (r)});
means for receiving the cone beam data and producing from the received cone beam data estimated cone beam values not provided by the received cone beam data;
means for receiving the estimated cone beam values and calculating from the estimated cone beam values corrected image data fC({right arrow over (r)}); and
summing means for combining the image data fD({right arrow over (r)}) with the corrected image data fC({right arrow over (r)}) to produce an image slice.
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Abstract
A computed tomography x-ray imaging system acquires a three-dimensional array of x-ray attenuation values using a cone beam x-ray source and a curved two-dimensional array of detector elements. Two-dimensional image slices are reconstructed using a filtered back projection method, and corrections are made to the images to account for incomplete data due to the cone beam geometry.
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Citations
9 Claims
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1. A computed tomography imaging system which comprises:
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a two-dimensional array of detector elements for receiving photons emanating in a cone beam from a source;
a digital acquisition system for acquiring two-dimensional arrays of cone beam data from the array of detector elements at a series of views in which the array of detector elements revolves around a central axis;
a filter for receiving the cone beam data and filtering the same;
means for back projecting the filtered cone beam data to produce image data fd({right arrow over (r)});
means for receiving the cone beam data and producing from the received cone beam data estimated cone beam values not provided by the received cone beam data;
means for receiving the estimated cone beam values and calculating from the estimated cone beam values corrected image data fC({right arrow over (r)}); and
summing means for combining the image data fD({right arrow over (r)}) with the corrected image data fC({right arrow over (r)}) to produce an image slice. - View Dependent Claims (2, 3, 4, 5)
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6. A method for producing an image with a computed tomography imaging system having a two-dimensional array of detector elements, the steps comprising:
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a) acquiring two-dimensional arrays of cone beam data from the array of detector elements at a series of views in which the array of detector elements revolves around a central axis;
b) filtering the acquired cone beam data;
c) back projecting the filtered cone beam data to produce image data fD({right arrow over (r)});
d) producing estimated cone beam values not provided by the acquired cone beam data, the estimated cone beam values being calculated from the acquired cone beam data;
e) calculating corrected image data fC({right arrow over (r)}) from the estimated cone beam values; and
f) producing an image slice by combining the image data fD({right arrow over (r)}) with the corrected image data fC({right arrow over (r)}). - View Dependent Claims (7, 8, 9)
i) determining boundaries in Radon space between regions therein for which complete cone beam data was acquired and regions therein for which cone beam data was not acquired; and
ii) interpolating between complete cone beam data at the Radon space boundaries to produce said estimated cone beam values.
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8. The method as recited in claim 6 which includes:
weighting the acquired cone beam data prior to filtering in step b).
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9. The method as recited in claim 6 which includes:
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preprocessing the acquired cone beam data to produce x-ray attenuation data for a three-dimensional region about the central axis; and
producing a plurality of two-dimensional image slices through said three-dimensional region in step f).
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Specification