Dual Axis Tomosynthesis Geometric Calibration via Projection Matrix
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Solution Overview
Problem
Conventional digital tomosynthesis systems with single-axis scans face limitations in imaging quality due to geometric misalignments and artifacts when transitioning to dual-axis scans, which are more complex and prone to kinematic errors.
Innovation Solution
A geometric calibration method and system using a calibration phantom with interlaced mark points on multiple plates, projected onto a detector to derive a projection matrix, allowing for the calculation of geometric parameters that correct for misalignments and improve image quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a dual-axis scan geometry is implemented to improve imaging quality and resolve indistinct imaging issues, then imaging quality is improved, but geometric misalignments and artifacts increase due to complex kinematic patterns
Solution Approach 1:
The patent performs geometric calibration before actual imaging by projecting a calibration phantom with known 3D coordinates and deriving a projection matrix to correct geometric misalignments in advance, preventing artifacts in subsequent imaging
Solution Approach 2:
The patent replaces mechanical alignment adjustments with a computational approach by deriving a projection matrix from calibration data to correct geometric misalignments through mathematical transformation rather than physical adjustment
2Measurement precision
If a calibration phantom with mark points on multiple plates is used to correct geometric misalignments, then geometric accuracy is improved, but the calibration process complexity increases
Solution Approach 1:
The patent uses a calibration phantom that creates a simplified 2D projection copy of the 3D geometric relationships, allowing complex 3D alignment problems to be solved through 2D coordinate mapping and projection matrix derivation
Solution Approach 2:
The patent transforms the geometric calibration problem by changing parameters from direct 3D spatial coordinates to 2D projected coordinates on the detector, enabling the use of projection geometry and matrix mathematics to solve alignment issues
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The method effectively reduces artifacts and enhances imaging quality by accurately determining and correcting geometric misalignments in dual-axis digital tomosynthesis systems, enabling better disease diagnosis and improved medical imaging.
Implementation Method 1
utilizing an X-ray to project the calibration phantom onto a planar detector, so as to obtain a projected calibration-phantom image
Data Source
AI summary
A geometric calibration method for dual-axis digital tomosynthesis includes the steps of: providing a calibration phantom having a first plate, a second plate parallel to the first plate, and mark points distributed to the first and second plates; arranging any mark point at the first plate not to be vertically collinear with a mark point at the second plate; projecting the calibration phantom onto a planar detector to obtain a projected calibration-phantom image; deriving a conversion relationship between the mark point and the corresponding projected position at the planar detector to further establish a projection matrix related to an imaging system; and, applying the projection matrix to calculate a plurality of geometric parameters. In addition, a geometric calibration system for dual-axis digital tomosynthesis is also provided.