Image generation from limited projections in positron emission tomography using multi-slice rebinning
First Claim
1. A method of reconstructing an image in a medical imaging system, the medical imaging system including a plurality of detectors capable of detecting a plurality of rays occurring within a range of projection angles, the rays including transverse rays and oblique rays, the method comprising the steps of:
- detecting the plurality of rays using the detectors;
generating a collection of data representative of the detected rays;
rebinning the data to create a stack of two-dimensional data sets corresponding to individual transverse slice images, wherein the slice images signify in the aggregate a three-dimensional image, wherein for each data set, the data included in said data set corresponds to less than all possible projection angles for the corresponding slice image;
applying a two-dimensional iterative reconstruction algorithm to each of the data sets to reconstruct a three-dimensional image slice-by-slice from the data sets; and
axially filtering the rebinned data.
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Abstract
A method of reconstructing an image in a medical imaging system comprises the steps of detecting transverse rays and oblique rays using a limited range of projection angles. The limited range of projection angles is achieved by either limiting the range of rotation of the detectors at each position along the z axis, or by causing the detectors to trace a continuous-motion helical path along the z axis. Data is then rebinned to create a stack of partially-complete sinograms corresponding to individual transverse slice images corresponding to, in the aggregate, a three-dimensional image. Because of the limited projection angles, each sinogram represents an incomplete data set. The rebinning includes, for each oblique ray, identifying among the sinograms the images intersected by the ray, and, applying to each of the sinograms associated with the images intersected by the ray an increment that is representative of the ray. A two-dimensional iterative reconstruction algorithm is applied to each partial sinogram in order to reconstruct a three-dimensional image slice-by-slice, followed or preceded by axially filtering to reduce blurring in the z direction.
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Citations
30 Claims
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1. A method of reconstructing an image in a medical imaging system, the medical imaging system including a plurality of detectors capable of detecting a plurality of rays occurring within a range of projection angles, the rays including transverse rays and oblique rays, the method comprising the steps of:
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detecting the plurality of rays using the detectors; generating a collection of data representative of the detected rays; rebinning the data to create a stack of two-dimensional data sets corresponding to individual transverse slice images, wherein the slice images signify in the aggregate a three-dimensional image, wherein for each data set, the data included in said data set corresponds to less than all possible projection angles for the corresponding slice image; applying a two-dimensional iterative reconstruction algorithm to each of the data sets to reconstruct a three-dimensional image slice-by-slice from the data sets; and axially filtering the rebinned data. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13)
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14. A method of reconstructing an image using a medical imaging system, the medical imaging system including a plurality of detectors capable of detecting a plurality of rays, the rays including transverse rays lying within a plurality of transverse planes and oblique rays not lying within the transverse planes, the detectors being rotatable about a z axis, the method comprising the steps of:
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performing a first scan pass along the z axis using to detectors to detect the rays over a range of projection angles, wherein the first scan pass is characterized by a helical path of relative motion between the detectors and an object to be imaged wherein the range of projection angles used is substantially less than 180 degrees for each of the transverse planes; converting the detected rays to a collection of data representative of the detected rays; rebinning the data to create a stack of two-dimensional data sets corresponding to individual transverse slice images, wherein the slice images signify in the aggregate a three-dimensional image, wherein the step of rebinning the data comprises the steps of; for each oblique ray, identifying among said data sets the images intersected by said ray; and applying to each of the data sets associated with the images intersected by the ray an increment representative of the ray; applying an iterative reconstruction algorithm to each of the data sets to reconstruct a three-dimensional image slice-by-slice from the data sets; and axially filtering the rebinned data. - View Dependent Claims (15, 16, 17, 18, 19)
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20. An apparatus for reconstructing an image in a medical imaging system, comprising:
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means for detecting both transverse and oblique rays emitted within a range of projection angles, the means for detecting including a plurality of detectors, the transverse rays lying within a plurality of transverse planes perpendicular to a z axis, the oblique rays not lying within the transverse planes, the projection angles defined within the transverse planes, wherein the range of projection angles is less than 180 degrees; means for converting the detected rays to data; means for collecting and assembling the data representative of the detected rays; means for rebinning the data to create a stack of two-dimensional data sets representative of individual transverse slice images, such that the slice images signify in the aggregate a three-dimensional image, the means for rebinning the data including; means for, for each oblique ray, identifying among said data sets the images intersected by said ray; and means for applying to each of the data sets associated with the images intersected by the ray an increment representative of the ray; means for applying a two-dimensional iterative reconstruction algorithm to each data set to reconstruct a three-dimensional image slice-by-slice from the data sets; and means for axially filtering the rebinned data. - View Dependent Claims (21, 22, 23, 24, 25, 26, 27, 28)
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29. In a medical imaging system having a detector for detecting radiation emitted from an object, the detector being rotatable relative to the object about an axis of rotation, a method of performing emission computed tomography, the method comprising the steps of:
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detecting radiation emitted from the object using a first scan pass characterized by a helical path of relative motion between the detector and the object; following completion of the first scan pass, rotating the detector approximately 90°
relative to the object to a starting position; anddetecting radiation emitted from the object using a second scan pass starting from the starting position, wherein the second scan pass is opposite in direction from the first scan pass and is characterized by a helical path of relative motion between the detector and the object, such that the first scan pass and the second scan pass together result in the acquisition of orthogonal sets of data.
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30. An apparatus for performing computed tomography imaging of an object, the apparatus comprising:
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a radiation detector that is rotatable relative to the object about an axis of rotation; means for controlling the radiation detector to detect radiation using a first scan pass characterized by a helical path of relative motion between the detector and the object; means for rotating the detector, following completion of the first scan pass, approximately 90°
relative to the object to a starting position; andmeans for controlling the detector to detect radiation using a second scan pass, the second scan pass starting from the starting position, wherein the second scan pass is opposite in direction from the first scan pass and is characterized by a helical path of relative motion between the detector and the object, such that the first scan pass and the second scan pass result in the acquisition of orthogonal sets of data.
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Specification