GEOMETRY CALIBRATION ALGORITHM FOR LARGE FLAT MODULE DETECTOR CT SCANNER
First Claim
1. A method for geometric calibration of a CT scanner having at least one row of detector cells, the method comprising:
- executing the following for each row of the at least one row of detector cells;
establishing a complete geometric description of the CT scanner, wherein the complete geometric description comprises at least one unknown geometric parameter;
establishing a description of a forward projection function using the complete geometric description;
acquiring actual projection coordinates of a calibration phantom placed in a scanning field of view (SFOV) on a current row of detector cells and corresponding to a plurality of angles;
acquiring calculated projection coordinates of the calibration phantom on the current row of detector cells and corresponding to the plurality of angles using the description of the forward projection function; and
acquiring a calibrated value for the at least one unknown geometric parameter by evaluating said at least one unknown geometric parameter based on the acquired actual projection coordinates and calculated projection coordinates using a nonlinear least square fitting algorithm.
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Abstract
A method for geometric calibration of a CT scanner, including, for each row of at least one row of detector cells, establishing a complete geometric description of the CT scanner, including at least one unknown geometric parameter, establishing a description of a forward projection function using the complete geometric description, acquiring actual projection coordinates of a calibration phantom placed in a scanning field of view (SFOV) on a current row of detector cells and corresponding to a plurality of angles, acquiring calculated projection coordinates of the calibration phantom on the current row of detector cells and corresponding to the plurality of angles using the description of the forward projection function, and acquiring a calibrated value for the at least one unknown geometric parameter by evaluating the at least one unknown geometric parameter based on the acquired actual projection coordinates and calculated projection coordinates via a nonlinear least square fitting algorithm.
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Citations
20 Claims
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1. A method for geometric calibration of a CT scanner having at least one row of detector cells, the method comprising:
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executing the following for each row of the at least one row of detector cells; establishing a complete geometric description of the CT scanner, wherein the complete geometric description comprises at least one unknown geometric parameter; establishing a description of a forward projection function using the complete geometric description; acquiring actual projection coordinates of a calibration phantom placed in a scanning field of view (SFOV) on a current row of detector cells and corresponding to a plurality of angles; acquiring calculated projection coordinates of the calibration phantom on the current row of detector cells and corresponding to the plurality of angles using the description of the forward projection function; and acquiring a calibrated value for the at least one unknown geometric parameter by evaluating said at least one unknown geometric parameter based on the acquired actual projection coordinates and calculated projection coordinates using a nonlinear least square fitting algorithm. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. An apparatus for geometric calibration of a CT scanner having at least one row of detector cells, the apparatus comprising:
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a geometric description establishing device configured to establish a complete geometric description of the CT scanner, the complete geometric description comprising at least one unknown geometric parameter; a forward projection function establishing device configured to establish a description of a forward projection function using the complete geometric description; an actual projection coordinate acquiring device configured to acquire actual projection coordinates of a calibration phantom placed in a scanning field of view (SFOV) on a current row of detector cells and corresponding to a plurality of angles; a calculated projection coordinate acquiring device configured to acquire calculated projection coordinates of the calibration phantom on the current row of detector cells and corresponding to the plurality of angles using the description of the forward projection function; and a calibrated value acquiring device configured for acquire a calibrated value for the at least one unknown geometric parameter by evaluating the at least one unknown geometric parameter based on the acquired actual projection coordinates and calculated projection coordinates via a nonlinear least square fitting algorithm. - View Dependent Claims (12, 13, 14, 15, 16, 17, 18, 19)
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20. A CT scan system, comprising:
- an apparatus for geometric calibration of a CT scanner having at least one row of detector cells
the apparatus comprising; a geometric description establishing device configured to establish a complete geometric description of the CT scanner, the complete geometric description comprising at least one unknown geometric parameter; a forward projection function establishing device configured to establish a description of a forward projection function using the complete geometric description; an actual projection coordinate acquiring device configured to acquire actual projection coordinates of a calibration phantom placed in a scanning field of view (SFOV) on a current row of detector cells and corresponding to a plurality of angles; a calculated projection coordinate acquiring device configured to acquire calculated projection coordinates of the calibration phantom on the current row of detector cells and corresponding to the plurality of angles using the description of the forward projection function; and a calibrated value acquiring device configured for acquire a calibrated value for the at least one unknown geometric parameter by evaluating the at least one unknown geometric parameter based on the acquired actual projection coordinates and calculated projection coordinates via a nonlinear least square fitting algorithm.
- an apparatus for geometric calibration of a CT scanner having at least one row of detector cells
Specification