X-ray CT Interpolation for Resolution Uniformity
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Solution Overview
Problem
The flying focal spot (FFS) method for X-ray CT devices results in non-uniform data sampling intervals and varying spatial resolution across imaging positions, leading to differences in spatial resolution between the imaging center and circumference in reconstructed images, which degrades measurement accuracy.
Innovation Solution
An X-ray CT device with a data interpolation part that corrects imaging position-dependent data sampling intervals and spatial resolution by using view direction and channel direction interpolation processing to generate interpolated projection data, allowing for position-dependent contribution ratios in reconstructed images.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the FFS method is used to double the density of X-ray transmission data, then sampling density around the rotation center axis is improved, but sampling intervals become non-uniform around the X-ray detection part
Solution Approach 1:
The patent applies local quality by performing different interpolation operations for different regions of the projection data. Specifically, it distinguishes between data in the vicinity of the rotation center axis (where view direction interpolation is applied) and data in the vicinity of the X-ray detection part (where channel direction interpolation is applied). This regional differentiation resolves the contradiction by optimizing each region according to its specific characteristics rather than applying a uniform interpolation method throughout.
2Measurement precision
If combination of projection data for counter view angle is taken into consideration in FFS method, then spatial resolution is improved around the imaging center, but spatial resolution degrades at positions remoter from the imaging center
Solution Approach 1:
The patent implements local quality by selecting different interpolation directions based on the spatial location of data points. For projection data corresponding to positions near the imaging center, view direction interpolation is used to maximize spatial resolution. For data corresponding to positions farther from the imaging center, channel direction interpolation is applied to maintain more uniform spatial resolution across the entire field of view. This position-dependent interpolation strategy resolves the contradiction between central and peripheral spatial resolution.
3Loss of information
If conventional interpolation processing is used for missing data in FFS method, then data completeness is improved, but spatial resolution difference between imaging center and circumference increases
Solution Approach 1:
The patent resolves this contradiction by applying locally optimized interpolation strategies. Instead of using a single conventional interpolation method for all missing data, the system performs view direction interpolation for missing data near the rotation center axis and channel direction interpolation for missing data near the X-ray detection part. This approach ensures both data completeness and maintains relatively uniform spatial resolution across different regions of the reconstructed image.
Solution Approach 2:
The patent applies dynamics by making the interpolation method adaptive to the specific characteristics of each data point's location. The system dynamically selects between view direction and channel direction interpolation based on the angular position and radial distance of each projection data point. This dynamic selection process ensures that the interpolation method is optimized for the local geometry, thereby maintaining spatial resolution uniformity while completing missing data.
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
This approach reduces the difference in spatial resolution across imaging positions, thereby improving measurement accuracy and optimizing image reconstruction in X-ray CT devices using the FFS method.
Implementation Method 1
an X-ray generation part (310) that generates an X-ray
Implementation Method 2
a technique called flying focal spot (FFS) method is disclosed in Patent document 1. The FFS method is a method of producing positional shift of X-ray beam by electromagnetically changing the position of the focal point of X-ray alternately between two positions during the rotational movement of the scanner
Data Source
AI summary
Difference of resolution depending on imaging position in one reconstructed image generated in the FFS method is reduced to improve measurement accuracy. The X-ray CT device interpolates missing data of the projection data obtained by the FFS method with view direction interpolation processing using real data of the projection data lining up along the angular direction of the rotational movement, and channel direction interpolation processing using real data of the projection data lining up along the channel direction, and generates a reconstructed image, in which contribution ratios of the projection data having been subjected to the view direction interpolation processing and the projection data having been subjected to the channel direction interpolation processing differ according to position of pixel in the reconstructed image.