Method of and system for stabilizing high voltage power supply voltages in multi-energy computed tomography
First Claim
1. A method of stabilizing commanded DC and AC voltages supplied by a High Voltage Power Supply (HVPS) in multi-energy X-ray computed tomography using projection data acquired by scanning objects, wherein the projection data include a set of low energy projections and a set of high energy projections using at least two x-ray spectra, wherein a copper filter is mounted relative to at least a portion of a scanner'"'"'s detector array, comprising:
- A. generating air ratios and copper ratios from said low and high energy projections;
B. computing voltage ratios from said air ratios and copper ratios;
C. computing HVPS DC and AC voltages from said voltage ratios;
D. providing feedback as a function of computed HVPS DC and AC voltages to simultaneously stabilize the commanded HVPS DC and AC voltages.
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Accused Products
Abstract
A method of and a system for stabilizing High Voltage Power Supply (HVPS) DC and AC voltages in multi-energy X-ray computed tomography scanners are provided. The method comprises generating filter ratios, computing DC and AC voltages, and feeding back the computed DC and AC voltages to the commanded voltages. The filtered ratios including an air ratio and a copper ratio are modeled as nonlinear functions of the DC and AC voltages. Computing DC and AC voltages include computing an m-ratio and an n-ratio. The parameters of the nonlinear model comprise an exponent parameter and a set of polynomial coefficients. The parameters are determined by a calibration procedure, which performs scanning at different combination of DC and AC voltages. The optimal parameters are obtained through a nonlinear least square minimization, which is solved through a brute force search over the exponent parameter and a closed form solution of the polynomial coefficients. Feeding back the computed DC and AC voltages include comparing the computed voltages with commanded voltages, integrating the difference between the computed voltages and commanded voltages, and adding the integrated voltage differences to the commanded voltages.
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Citations
29 Claims
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1. A method of stabilizing commanded DC and AC voltages supplied by a High Voltage Power Supply (HVPS) in multi-energy X-ray computed tomography using projection data acquired by scanning objects, wherein the projection data include a set of low energy projections and a set of high energy projections using at least two x-ray spectra, wherein a copper filter is mounted relative to at least a portion of a scanner'"'"'s detector array, comprising:
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A. generating air ratios and copper ratios from said low and high energy projections; B. computing voltage ratios from said air ratios and copper ratios; C. computing HVPS DC and AC voltages from said voltage ratios; D. providing feedback as a function of computed HVPS DC and AC voltages to simultaneously stabilize the commanded HVPS DC and AC voltages. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 29)
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19. A system for stabilizing commanded DC and AC voltages supplied by a High Voltage Power Supply (HVPS) in multi-energy X-ray computed tomography using projection data acquired by scanning objects, wherein the projection data include a set of low energy projections and a set of high energy projections using at least two x-ray spectra, wherein a copper filter is mounted relative to at least a portion of a scanner'"'"'s detector array, comprising:
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A. a component constructed and arranged so as to generate air ratios and copper ratios from said low and high energy projections; B. a component constructed and arranged so as to generate voltage ratios from said air ratios and cooper ratios; C. a component constructed and arranged so as to compute HVPS DC and AC voltages from said voltage ratios; and D. a component constructed and arranged so as to provide feedback as a function of computed HVPS DC and AC voltages to simultaneously stabilize the commanded HVPS DC and AC voltages. - View Dependent Claims (20, 21, 22, 23, 24, 25, 26, 27, 28)
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Specification