Motion Vector Field Calculation for CT Scan Image Reconstruction
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Solution Overview
Problem
Current CT scanning techniques face limitations in achieving high temporal resolution and reducing motion artifacts due to the mechanical speed constraints, necessitating the calculation of a motion vector field in reconstructed CT scan images for motion-compensated reconstruction.
Innovation Solution
The method involves calculating motion vectors based on projection data from different time points, determining the motion vector field, and applying motion compensation to reconstruct images with higher time resolution and reduced artifacts by adjusting the motion vector field using an extension factor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If the gantry rotation speed is increased to improve temporal resolution, then the scanning time is reduced, but mechanical constraints limit further speed improvement
Solution Approach 1:
The patent replaces the mechanical solution of increasing gantry rotation speed with a computational approach. Motion vectors are calculated based on projection data from different time points, and motion compensation is applied during image reconstruction. This substitutes mechanical speed improvement with algorithmic motion correction, achieving high temporal resolution without being constrained by mechanical limits.
2Object-affected harmful factors
If the gantry rotation speed is increased to reduce motion artifacts, then the scanning time is reduced, but motion artifacts persist due to mechanical speed constraints
Solution Approach 1:
The patent replaces mechanical speed increase with a computational motion compensation system. Motion vectors are derived from projection data at different time points, and these vectors are used to correct for motion during image reconstruction. This computational approach eliminates motion artifacts without requiring faster mechanical rotation.
Solution Approach 2:
The patent performs preliminary calculation of motion vectors from projection data before final image reconstruction. By pre-calculating the motion compensation parameters based on earlier projection data, the system can correct for motion artifacts in the final reconstructed image, preventing rather than merely addressing the problem.
3Manufacturing precision
If motion compensation is applied to improve image quality, then temporal resolution and artifact reduction are improved, but calculation complexity increases
Solution Approach 1:
The patent segments the image reconstruction process into distinct stages: first calculating motion vectors from projection data, then applying motion compensation during reconstruction. This segmentation allows the complex task to be broken down into manageable steps, improving precision while organizing the computational complexity into structured phases.
Data Source
AI summary
A method for calculating a motion vector field (MVF) in a reconstructed CT scan image, comprises: determining a region of interest (ROI) based on a vessel centreline in a first reconstructed CT scan image, wherein a motion vector field (MVF) for the ROI is to be calculated; determining at least two time control points for calculating the MVF; calculating a motion level factor of the ROI; calculating motion amounts of the MVF corresponding to each of the time control points; determining the direction of the MVF of the ROI; and calculating the MVF of the ROI according to the motion level factor, the motion amounts of the MVF corresponding to each of the time control points and the direction of the MVF.