Method of and system for computing effective atomic number images in multi-energy computed tomography
First Claim
1. A method of computing Z images from the CT projection data acquired by scanning a set of objects using at least two x-ray spectra, wherein said projection data includes a set of low energy projections and a set of high energy projections, comprising:
- a. reconstructing a CT image from one of the two sets of projections, which are not processed by any decomposition methods;
b. obtaining the photoelectric projections from the high energy projections and low energy projections without decomposition to Compton projections;
c. reconstructing a photoelectric image from the photoelectric projections; and
d. computing the Z image from the photoelectric image and the CT image, without using any Compton images.
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Abstract
A method of and a system for computing Z (effective atomic number) images from projection data are provided, wherein the projections are acquired using at least two x-ray spectra for a set of scanned objects, including a set of low energy projections and a set of high energy projections; the method comprises decomposing the low energy projections and high energy projections into photoelectric projections, reconstructing the photoelectric projections into photoelectric images, reconstructing one of the two sets of projections into CT images, and computing Z images from the CT images and the photoelectric images with parameters obtained from a calibration procedure.
120 Citations
14 Claims
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1. A method of computing Z images from the CT projection data acquired by scanning a set of objects using at least two x-ray spectra, wherein said projection data includes a set of low energy projections and a set of high energy projections, comprising:
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a. reconstructing a CT image from one of the two sets of projections, which are not processed by any decomposition methods; b. obtaining the photoelectric projections from the high energy projections and low energy projections without decomposition to Compton projections; c. reconstructing a photoelectric image from the photoelectric projections; and d. computing the Z image from the photoelectric image and the CT image, without using any Compton images. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A system for computing Z images from the projection data acquired by scanning a set of objects using at least two x-ray spectra, wherein said projection data includes a set of low energy projections and a set of high energy projections, comprising:
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a. a reconstruction subsystem constructed and arranged so as to reconstruct CT images from one of the two sets of projections, which are not processed by any decomposition methods; b. a dual energy decomposition subsystem constructed and arranged so as to obtain the photoelectric projections from low energy projections and high energy projections without decomposition to Compton projections; c. a reconstruction subsystem constructed and arranged so as to reconstruct photoelectric images from the photoelectric projections; and d. a Z image calculator constructed and arranged so as to compute the Z images from the CT images and the photoelectric images, without using any Compton images. - View Dependent Claims (9, 10, 11, 12, 13, 14)
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Specification