Computed tomography method and apparatus for acquiring images dependent on a time curve of a periodic motion of the subject
First Claim
1. A method for producing a computed tomography (CT) image comprising the steps of:
- (a) scanning a subject, having a region exhibiting a periodic motion, with a conical x-ray beam emanating from a focus and detecting said beam, after attenuation by said subject, with a matrix-like detector array while moving said focus along a spiral path around said subject relative to a system axis, said detector array generating output data dependent on radiation from said x-ray beam that is incident thereon;
(b) dividing said output data, for a segment of said spiral path having a length adequate for reconstructing a CT image, into a plurality of datasets respectively for a plurality of sub-segments of said segment, each of said sub-segments having a length shorter than said length adequate for reconstructing a CT image;
(c) for each of said sub-segments, reconstructing a plurality of segment images having a plane inclined relative to said system axis from the dataset for that sub-segment;
(d) obtaining a signal representing a time curve of said periodic motion during said scanning;
(e) allocating a z-position on said system axis and a time position with respect to said periodic motion to the respective segment images;
(f) selecting segment images within a range of z-positions and a range of time positions so that the respective sub-segments of the selected segment images comprise a total length adequate for reconstruction of a CT image; and
(g) at least indirectly combining the selected segment images to form a resulting CT image with respect to a target image plane.
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Abstract
In a computed tomography method and apparatus, having a subject with a conical ray beam emanating from a focus and with a matrix-like detector array for detecting the ray beam, while the focus is moved on a spiral path around a system axis relative to the subject, and the detector array supplies output data corresponding to the received radiation. The output data respectively supplied during the motion of the focus on a spiral segment and having a length adequate for the reconstruction of a CT image are divided into output data with respect to sub-segments, with the length of each sub-segments being shorter than the length required for the reconstruction of a CT image. Segment images having an inclined image plane relative to the system axis are reconstructed for the sub-segments. A signal reproducing the time curve of the periodic motion is acquired during the scanning. A z-position on the system axis and a time position with respect to the periodic motion are allocated to the segment images. Segment images belonging to a desired range of z-positions and a desired range of time positions are selected such that the corresponding sub-segments have an overall length adequate for the reconstruction of a CT image. The selected segment images are at least indirectly combined into a resulting CT image with respect to a target image plane.
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Citations
80 Claims
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1. A method for producing a computed tomography (CT) image comprising the steps of:
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(a) scanning a subject, having a region exhibiting a periodic motion, with a conical x-ray beam emanating from a focus and detecting said beam, after attenuation by said subject, with a matrix-like detector array while moving said focus along a spiral path around said subject relative to a system axis, said detector array generating output data dependent on radiation from said x-ray beam that is incident thereon;
(b) dividing said output data, for a segment of said spiral path having a length adequate for reconstructing a CT image, into a plurality of datasets respectively for a plurality of sub-segments of said segment, each of said sub-segments having a length shorter than said length adequate for reconstructing a CT image;
(c) for each of said sub-segments, reconstructing a plurality of segment images having a plane inclined relative to said system axis from the dataset for that sub-segment;
(d) obtaining a signal representing a time curve of said periodic motion during said scanning;
(e) allocating a z-position on said system axis and a time position with respect to said periodic motion to the respective segment images;
(f) selecting segment images within a range of z-positions and a range of time positions so that the respective sub-segments of the selected segment images comprise a total length adequate for reconstruction of a CT image; and
(g) at least indirectly combining the selected segment images to form a resulting CT image with respect to a target image plane. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40)
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41. A computed tomography (CT) apparatus comprising:
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a CT scanner having an x-ray source with a focus and a matrix-like detector array for scanning a subject, having a region exhibiting a periodic motion, with a conical x-ray beam emanating from said focus and detecting said beam, after attenuation by said subject, with said matrix-like detector array while moving said focus along a spiral path around said subject relative to a system axis, said detector array generating output data dependent on radiation from said x-ray beam that is incident thereon;
a signal acquisition unit adapted for interaction with said subject for obtaining a signal from said subject representing said periodic motion;
a computer supplied with said output data and said signal, said computer dividing said output data, for a segment of said spiral path having a length adequate for reconstructing a CT image, into a plurality of datasets respectively for a plurality of sub-segments of said segment, each of said sub-segments having a length shorter than said length adequate for reconstructing a CT image;
said computer, for each of said sub-segments, reconstructing a plurality of segment images having a plane inclined relative to said system axis from the dataset for that sub-segment;
said computer allocating a z-position on said system axis and a time position with respect to said periodic motion to the respective segment images;
said computer selecting segment images within a range of z-positions and a range of time positions so that respective sub-segments for the selected segment images comprise a total length adequate for reconstruction of a CT image; and
said computer combining said selected segment images at least indirectly to form a resulting CT image with respect to a target image plane. - View Dependent Claims (42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80)
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Specification