Methods and apparatus for reducing z-axis non-uniformity artifacts
First Claim
1. A system for calibrating projection data for generating a tomographic image of an object, said system comprising an x-ray source and a detector array comprising a plurality of cells arranged in rows and columns and displaced along a z-axis, the detector array column cells being arranged in channels, said system being configured to:
- determine an x-ray beam z-axis profile; and
determine a true x-ray flux utilizing detector gain profiles and the determined x-ray beam profile;
wherein;
said system being configured to determine an x-ray beam z-axis profile comprises said system being configured to obtain signals from a select number of detector cells in at least one channel of the detector array; and
said system being configured to obtain signals from a selected number of detector cells comprises said system being configured to select at least one detector cell having a uniform gain measurement.
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Accused Products
Abstract
Methods and apparatus of correcting image data for z-axis non-uniformity in a computed tomography (CT) system are described. In one embodiment, the CT system includes a configurable multislice detector array and a calibration algorithm. In accordance with one embodiment of the algorithm, output signals from a plurality of detector cells are sampled to generate an x-ray beam z-axis non-uniformity profile. The x-ray beam z-axis profile is then used to determine a detector z-axis non-uniformity profile for the detector array. Utilizing the z-axis profiles, the output signals from the detector cells may be calibrated to reduce z-axis non-uniformity errors.
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Citations
48 Claims
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1. A system for calibrating projection data for generating a tomographic image of an object, said system comprising an x-ray source and a detector array comprising a plurality of cells arranged in rows and columns and displaced along a z-axis, the detector array column cells being arranged in channels, said system being configured to:
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determine an x-ray beam z-axis profile; and determine a true x-ray flux utilizing detector gain profiles and the determined x-ray beam profile; wherein; said system being configured to determine an x-ray beam z-axis profile comprises said system being configured to obtain signals from a select number of detector cells in at least one channel of the detector array; and said system being configured to obtain signals from a selected number of detector cells comprises said system being configured to select at least one detector cell having a uniform gain measurement.
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2. A method for calibrating projection data in a multi-slice computed tomography system, the system including an x-ray source and a detector array comprising a plurality of cells arranged in rows and columns and displaced along a z-axis, and the detector array cells are arranged in channels, said method comprising the steps of:
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determining an x-ray beam z-axis profile including obtaining signals from detector cells in at least one fully sampled channel of the detector array; and determining a true x-ray flux utilizing detector gain profiles and the determined x-ray beam profile. - View Dependent Claims (3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17)
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18. A system for calibrating projection data for generating a tomographic image of an object, said system comprising an x-ray source and a detector array comprising a plurality of cells arranged in rows and columns and displaced along a z-axis, the detector array column cells being arranged in channels, said system being configured to:
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determine an x-ray beam z-axis profile; and determine a true x-ray flux utilizing detector gain profiles and the determined x-ray beam profile; wherein; said system being configured to determine an x-ray beam z-axis profile comprises said system being configured to obtain signals from a select number of detector cells in at least one channel of the detector array; said system being configured to determine an x-ray beam z-axis profile comprises said system being configured to; estimate an x-ray flux profile; adjust the output signals of each channel; and generate a revised x-ray beam z-axis profile utilizing the adjusted output signals.
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19. A system for calibrating projection data for generating a tomographic image of an object, said system comprising an x-ray source and a detector array comprising a plurality of cells arranged in rows and columns and displaced along a z-axis, wherein said detector cell columns are arranged in channels said system configured to:
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determine at least one z-axis x-ray beam profile; and determine a true x-ray flux utilizing detector gain profiles and said determined x-ray beam profile; and wherein to determine said x-ray beam profile, said system is configured to obtain signals from a select number of detector cells in at least one channel of said detector array. - View Dependent Claims (20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34)
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35. A method for calibrating projection data in a multislice computed tomography system, the system including an x-ray source and a detector array comprising a plurality of cells arranged in rows and columns and displaced along a z-axis, the detector array column cells being arranged in channels, said method comprising the steps of:
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determining an x-ray beam z-axis profile, including obtaining signals from a select number of detector cells in at least one channel of the detector array; and determining a true x-ray flux utilizing detector gain profiles and the determined x-ray beam profile; wherein obtaining signals from a selected number of detector cells comprises the step of selecting at least one detector cell having a uniform gain measurement.
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36. A method for calibrating projection data in a multislice computed tomography system, the system including an x-ray source and a detector array comprising a plurality of cells arranged in rows and columns and displaced along a z-axis, the detector array column cells being arranged in channels, said method comprising the steps of:
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determining an x-ray beam z-axis profile, including obtaining signals from a select number of detector cells in at least one channel of the detector array; and determining a true x-ray flux utilizing detector gain profiles and the determined x-ray beam profile; wherein determining an x-ray beam z-axis profile comprises the steps of; estimating an x-ray flux profile; adjusting the output signals of each channel; and generating a revised x-ray beam z-axis profile utilizing the adjusted output signals.
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37. A method for calibrating projection data in a multislice computed tomography system, the system including an x-ray source and a detector array comprising a plurality of cells arranged in rows and columns and displaced along a z-axis, the detector array column cells arranged in channels, said method comprising the steps of:
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determining an x-ray beam z-axis profile including obtaining signals from a select number of detector cells in at least one channel of the detector array; determining a true x-ray flux utilizing detector gain profiles and the determined x-ray beam profile; adjusting the projection data using the detector gain profiles and the determined x-ray flux profiles, including generating a gain profile for each non-selected detector cell; wherein generating a gain profile for each non-selected detector cell comprises the step of determining a measured output signal, wherein the measured output signal, y'"'"', is;
##EQU8## - View Dependent Claims (38, 39, 40, 41, 42)
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43. A system for calibrating projection data for generating a tomographic image of an object, said system comprising an x-ray source and a detector array comprising a plurality of cells arranged in rows and columns and displaced along a z-axis, the detector array column cells being arranged in channels, said system configured to:
- determine an x-ray beam z-axis profile;
determine a true x-ray flux utilizing detector gain profiles and the determined x-ray beam profile; and adjust the projection data using the detector gain profiles and the determined x-ray flux profiles; wherein; said system being configured to determine an x-ray beam z-axis profile comprises said system being configured to obtain signals from a select number of detector cells in at least one channel of the detector array; said system being configured to adjust the projection data includes said system being configured to generate a gain profile for each non-selected detector cell; and said system being configured to generate a gain profile for each non-selected detector cell comprises said system being configured to determine a measured output signal, wherein the measured output signal, y'"'"', is;
##EQU10## - View Dependent Claims (44, 45, 46, 47, 48)
- determine an x-ray beam z-axis profile;
Specification