X-ray CT Reconstruction with CT Value Shift Correction
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Solution Overview
Problem
The circular orbit cone beam reconstruction method in X-ray computer tomography results in low image quality and distortion in mask areas due to incomplete projection data, leading to exclusion of these areas from reconstruction and potential CT value shifts.
Innovation Solution
An X-ray computer tomography apparatus that includes a reconstruction processing unit capable of full and short scan image reconstruction, a CT value shift distribution generating unit, and a correcting unit to address CT value shifts by generating and correcting images based on spatial distributions of CT value shifts, thereby improving image quality in mask areas.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If mask areas are excluded from image reconstruction processing, then image quality in non-mask areas is maintained, but the reconstruction area is reduced and imaging coverage is lost
Solution Approach 1:
The patent applies local quality by differentiating processing between mask areas and non-mask areas. Full scan projection data is used for mask areas to ensure adequate angular coverage, while short scan data is used for non-mask areas to enable faster reconstruction. This localized differentiation allows the entire reconstruction area to be utilized without compromising overall image quality.
Solution Approach 2:
The patent segments the reconstruction area into mask areas and non-mask areas based on angular coverage criteria. This segmentation enables selective application of different reconstruction algorithms and data sources, allowing comprehensive coverage while maintaining quality standards in each region.
2Area of stationary object
If mask areas are forced to be reconstructed using short scan data, then reconstruction area is expanded, but distortion, shape reproducibility deterioration, and CT value shifts occur
Solution Approach 1:
The patent changes the parameter of angular coverage threshold to identify mask areas. By setting a specific threshold for minimum angular coverage, the system automatically determines which areas require full scan data versus short scan data, dynamically adjusting reconstruction parameters based on local data adequacy.
Solution Approach 2:
The patent introduces an intermediary classification mechanism that evaluates angular coverage and assigns areas to appropriate reconstruction categories. This intermediary step prevents direct reconstruction of mask areas with insufficient data, thereby avoiding distortion and shape reproducibility issues.
3Manufacturing precision
If full scan projection data is used for all areas, then image quality is maintained, but scanning time and data processing load increase
Solution Approach 1:
The patent applies partial action by using full scan data only where necessary (in mask areas) and short scan data where sufficient (in non-mask areas). This selective approach achieves the minimum necessary data collection for quality reconstruction while minimizing scanning time and processing load.
Solution Approach 2:
The patent introduces dynamic selection of reconstruction data sources based on spatial location and angular coverage characteristics. The system adaptively chooses between full scan and short scan data for different regions, optimizing the balance between image quality and scanning efficiency.
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 solution effectively reduces distortion and CT value shifts in mask areas by adjusting view counts for reconstruction and correcting short scan images, enhancing image quality and shape reproducibility.
Implementation Method 1
an X-ray tube which generates cone beam X-rays
Implementation Method 2
a two-dimensional array type X-ray detector which detects X-rays transmitted through an object and generates projection data
Data Source
AI summary
An X-ray computer tomography apparatus includes a cone beam X-ray tube X-rays, a two-dimensional array type X-ray detector, a rotating mechanism which supports the X-ray tube, together with the X-ray detector, so as to be rotatable around the object, a reconstruction processing unit which reconstructs a full scan image based on projection data, of the projection data, which corresponds to a view count corresponding to one rotation and also reconstructs a short scan image based on projection data corresponding to a view count smaller than the view count corresponding to one rotation, a CT value shift distribution generating unit which generates a spatial distribution of CT value shifts originating from the smaller view count based on the full scan image and the short scan image, and a correcting unit which corrects the short scan image based on the spatial distribution of the CT value shifts.