Calibration phantom, method, and system
Inventors
Eriksson, Markus • da Silva, Joakim Sebastian
Assignees
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Publication Number
US-12629127-B2
Publication Date
2026-05-19
Expiration Date
Abstract
Disclosed herein is a calibration phantom for calibrating an imaging scanner. The imaging scanner comprises a rotatable gantry, and a source of imaging radiation and a detector both configured to rotate with the gantry. The calibration phantom comprises a support structure and a plurality of boards, wherein each board comprises a planar calibration pattern formed of radiopaque material. The boards are positioned along a first axis and each board is positioned, by the support structure, at an angle with respect to each of the other boards such that each planar calibration pattern faces a different direction. The directions faced by each planar calibration pattern are substantially perpendicular to the first axis.
Core Innovation
The calibration phantom comprises boards positioned along a linear first axis, each bearing a planar calibration pattern formed of radiopaque material. A support structure positions the boards at different angles so that the patterns face different directions substantially perpendicular to the first axis. This arrangement keeps patterns visible across gantry angles, including half-fan imaging, and supports correspondence between partial, opposing projections.
The disclosed method, computer-readable medium, and system use projection images of the phantom to determine calibration parameters indicating differences between nominal and true positions or orientations of imaging-scanner components. The calibration may address gravity-related flex and determine source or detector parameters as a function of gantry angle. The supplied content does not include the background section, so the problem stated there is not explicitly described in patent.
Claims Coverage
The four independent claims are claims 1, 12, 18, and 19. They cover four inventive features: a calibration phantom, a calibration method, a computer-readable medium, and a calibration system.
Calibration phantom with differently oriented patterns
Claim 1 covers a support structure and multiple boards positioned along a linear first axis. Each board comprises a radiopaque planar calibration pattern, and the boards are angled so that the patterns face different directions substantially perpendicular to the first axis.
Calibration based on projection images
Claim 12 covers receiving projection images of a phantom with radiopaque calibration patterns on differently oriented boards, acquired from multiple gantry rotation angles, and determining a calibration parameter that indicates a difference between a scanner component's nominal and true position or orientation.
Computer-readable medium for determining calibration parameters
Claim 18 covers computer-executable instructions that receive projection images of a phantom with radiopaque calibration patterns on differently oriented boards and determine, based on those images, a calibration parameter indicating a difference between a scanner component's nominal and true position or orientation.
System for calibrating an imaging scanner
Claim 19 covers a system comprising a phantom with radiopaque calibration patterns on differently oriented boards and a computer-readable medium. The instructions cause a processor to receive projection images taken at multiple gantry rotation angles and determine a calibration parameter indicating a difference between a scanner component's nominal and true position or orientation.
The independent claims cover the phantom structure and three ways of using projection images of that phantom to determine imaging-scanner calibration parameters.
Stated Advantages
The differently oriented patterns remain visible across gantry angles, including half-fan imaging.
Checkerboard patterns enable precise feature localization and robust correspondence between partial, opposing projections.
The phantom reduces dependence on precise assembly and lowers manufacturing complexity and cost compared with ball-bearing phantoms.
Calibration results can improve image reconstruction.
Documented Applications
Calibration of an imaging scanner, including a CBCT imaging scanner.
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