Registration correction for radiographic scanners with sandwich detectors
First Claim
1. A radiographic apparatus comprising:
- a source of radiation for projecting a radiation beam through an examination region which receives a subject to be examined radiographically;
an array of first radiographic detectors for detecting radiation that has traversed the examination region and generating first signals indicative thereof;
an array of second radiographic detectors for detecting radiation that has traversed the examination region and generating second signals indicative thereof;
a transform means for deriving an image representation from the first and second signals, the transform means being operatively connected with the first and second detector arrays;
a registration correction means for operating on at least one of the first and second signals to correct for spatial misalignment of the first and second detector arrays, the registration correction means being operatively connected between the transform means and at least one of the first and second arrays.
1 Assignment
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Accused Products
Abstract
A fan beam of radiation (12) is projected on first and second detector arrays (18, 20). The detector arrays and fan beam are swept across a phantom (D). Fine wires (82) in the phantom each cast shadows over fractions of a plurality of the detectors during the sweep. Phantom images (44, 46) are generated from the first and second detector arrays with corresponding pixels of each image corresponding to the same path between a radiation source (10) and corresponding detectors in the arrays. A linear interpolation (50) interpolates the pixels of one of the images to shift their effective spatial position. A transform means (52) transforms the linear interpolated and second phantom image into at least one composite image (54). The linear interpolation is iteratively adjusted (C) to minimize phase change artifacts in corresponding pixels of the composite image. After the appropriate interpolation for each detector or group of detectors has been determined, the appropriate linear interpolations are stored (72). Thereafter, the stored linear interpolations are utilized each time a subject is examined.
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Citations
23 Claims
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1. A radiographic apparatus comprising:
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a source of radiation for projecting a radiation beam through an examination region which receives a subject to be examined radiographically; an array of first radiographic detectors for detecting radiation that has traversed the examination region and generating first signals indicative thereof; an array of second radiographic detectors for detecting radiation that has traversed the examination region and generating second signals indicative thereof; a transform means for deriving an image representation from the first and second signals, the transform means being operatively connected with the first and second detector arrays; a registration correction means for operating on at least one of the first and second signals to correct for spatial misalignment of the first and second detector arrays, the registration correction means being operatively connected between the transform means and at least one of the first and second arrays. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13)
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14. A radiographic apparatus comprising:
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means for projecting a fan beam of radiation along a plane; a plurality of arrays of radiation detectors for detecting radiation and generating radiation signals indicative of the amount of radiation detected thereby, the detector arrays being disposed to detect radiation which has trasversed an at least partially common path; a phantom disposed between the radiation source and the detector arrays, the phantom including a plurality of strips of radiation absorptive material that are narrower than a width of a detector element in the arrays, the strips extending at an oblique angle relative to the fan beam plane; a drive means for sweeping the fan beam and detector arrays at an oblique angle relative to the phantom strips such that the strips of radiation absorptive material cast shifting shadows on a plurality of the detectors. - View Dependent Claims (15)
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16. A radiographic apparatus comprising:
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means for projecting a fan beam of radiation; a plurality of arrays of radiation detectors for detecting radiation and generating radiation signals indicative of the amount of radiation detected thereby, the detector arrays being disposed to detect radiation which has traversed an at least partially common path; a phantom disposed between the radiation source and the detector arrays, the phantom including a plurality of strips of radiation absorptive material extending at an angle relative to the fan beam plane; a drive means for sweeping the fan beam and detector arrays relative to the phantom such that the strips of radiation absorptive material cast shadows on a plurality of the detectors; first and second phantom image memory means for storing first and second phantom images, the first and second phantom image memory means being operatively connected with the plurality of detectors for receiving the first and second signals therefrom; a registration correction means operatively connected with at least the first phantom image memory means for interpolating values of adjacent pixels of the first phantom image memory; a transform means operatively connected with the registration correction means and the second phantom image memory means for transforming the registration corrected pixel values from the first phantom image memory means and pixel values from the second phantom image memory means into at least one composite image representation; and
,a composite image memory means for storing the composite image representation. - View Dependent Claims (17, 18, 19, 20)
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21. A method of radiography comprising:
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(a) collecting data representing generally the same spatial paths through an image region with each of at least two detector arrays; (b) repeating step (a) for each of a plurality of spatial paths at least some of which intersect segments of radiation absorptive material such that any misalignment in the spatial paths of corresponding detectors in the at least two arrays causes phase change artifacts; (c) interpolating data collected by corresponding detectors of the at least two arrays to bring the spatial path detected by the corresponding detectors into more precise spatial alignment; (d) after interpolation, transforming the data from the detector arrays into at least one composite image representation. - View Dependent Claims (22, 23)
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Specification