Cone beam type of X-ray CT system for three-dimensional reconstruction
First Claim
1. An X-ray CT system comprising:
- an X-ray source for radiating a cone-beam X-ray;
a two-dimensional X-ray detector for detecting the X-ray radiated from the X-ray source through an object to be examined and for outputting projection data depending on an amount of the detected X-ray;
scanning means configured to scan the object with the X-ray radiated from the X-ray source within a particular scan range predetermined spatially under a desired scan technique involving at least a movement of the X-ray source along a predetermined orbit for the scan, thus enabling the X-ray detector to acquire the projection data generated during the scan;
a Radon data producing means for producing three-dimensional Radon data distributed three-dimensionally, from the projection data acquired by the scanning means;
weighting means for weighting the three-dimensional Radon data using a weighting function providing a non-constant weight in which a degree of reliability of the projection data is reflected, the degree of reliability being previously determined depending on an acquisition time of the projection data during the scan along the orbit; and
reconstruction means for reconstructing the three-dimensional Radon data weighted by the weighting means, based on a desired three-dimensional reconstruction algorithm, the reconstruction providing an image.
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Abstract
An X-ray CT system is equipped with a gantry, couch and control cabinet and configured to scan a cone-beam X-ray toward an object along a given orbit to acquire cone-beam data in which a three-dimensional distribution of an X-ray absorption coefficient within the object is reflected. The control cabinet decides a degree of reliability for the cone-beam data according to an acquisition time of the cone-beam data, and then decides a weight for three-dimensional Radon data from the cone-beam data on the basis of the degree of reliability. Using this weight, the control cabinet reconstructs the three-dimensional Radon data based on a three-dimensional reconstruction algorithm. Thus, when the three-dimensional reconstruction algorithm for cone-beam CT is applied to medical CT, artifacts attributable to object'"'"'s motion can be suppressed and temporal resolution can be improved.
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Citations
25 Claims
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1. An X-ray CT system comprising:
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an X-ray source for radiating a cone-beam X-ray;
a two-dimensional X-ray detector for detecting the X-ray radiated from the X-ray source through an object to be examined and for outputting projection data depending on an amount of the detected X-ray;
scanning means configured to scan the object with the X-ray radiated from the X-ray source within a particular scan range predetermined spatially under a desired scan technique involving at least a movement of the X-ray source along a predetermined orbit for the scan, thus enabling the X-ray detector to acquire the projection data generated during the scan;
a Radon data producing means for producing three-dimensional Radon data distributed three-dimensionally, from the projection data acquired by the scanning means;
weighting means for weighting the three-dimensional Radon data using a weighting function providing a non-constant weight in which a degree of reliability of the projection data is reflected, the degree of reliability being previously determined depending on an acquisition time of the projection data during the scan along the orbit; and
reconstruction means for reconstructing the three-dimensional Radon data weighted by the weighting means, based on a desired three-dimensional reconstruction algorithm, the reconstruction providing an image. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A three-dimensional reconstruction method comprising the steps of:
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acquiring two-dimensional projection data into which a three-dimensional distribution of an X-ray absorption coefficient of an object to be examined is reflected, by scanning the object with a cone-beam X-ray;
producing three-dimensional Radon data from the projection data;
correcting the three-dimensional Radon data based on a weighting function in which a degree of reliability of the projection data is reflected, the degree of reliability being previously decided depending on an acquisition time of the projection data; and
reconstructing the three-dimensional Radon data based on a three-dimensional reconstruction algorithm to obtain an image of the object. - View Dependent Claims (12, 13, 14)
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15. The three-dimensional reconstruction method according to claim 15, wherein the scan technique of the cone-beam X-ray is one selected from a group of scan techniques including a scan technique based on a circular-orbit full scan representing as the orbit a one-time circular orbit, a circular-orbit half scan (MHS:
- Modified Half Scan) along an extended circle using the projection data from the scan range of 360 degrees while the orbit representing a one-time circular orbit, a circular-orbit under scan representing as the orbit a one-time circular orbit, a circular-orbit scan representing as the orbit two or more rotations along a circular orbit, a scan representing as the orbit an orbit formed by combining a linear orbit and a circular orbit, and a helical scan representing as the orbit a helical orbit.
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16. A weight setting method for X-ray CT comprising the steps of:
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deciding a degree of reliability for two-dimensional projection data on the basis of a acquisition time of the two-dimensional projection data in which a three-dimensional distribution of an X-ray absorption coefficient of an object to be examined is reflected, the three-dimensional distribution being acquired with a cone-beam X-ray; and
deciding a weight used to correct a three-dimensional Radon data obtained from the projection data on the basis of the degree of reliability. - View Dependent Claims (17)
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18. An X-ray CT system comprising:
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an X-ray source configured to radiate a cone-beam X-ray;
a two-dimensional X-ray detector configured to detect the X-ray radiated from the X-ray source through an object to be examined and output projection data depending on an amount of the detected X-ray;
a scanning unit configured to scan the object with the X-ray radiated from the X-ray source within a particular scan range predetermined spatially under a desired scan technique involving at least a movement of the X-ray source along a predetermined orbit for the scan, thus enabling the X-ray detector to acquire the projection data generated during the scan;
a Radon data producing unit configured to produce three-dimensional Radon data distributed three-dimensionally, from the projection data acquired by the scanning unit;
a weighting unit configured to weight the three-dimensional Radon data using a weighting function providing a non-constant weight in which a degree of reliability of the projection data is reflected, the degree of reliability being previously determined depending on an acquisition time of the projection data during the scan along the orbit; and
a reconstruction unit configured to reconstruct the three-dimensional Radon data weighted by the weighting unit, based on a desired three-dimensional reconstruction algorithm, the reconstruction providing an image. - View Dependent Claims (19, 20, 21, 22, 23, 24, 25)
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Specification