CT SOD Shift Correction via Image Sharpness Analysis
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Solution Overview
Problem
Existing CT devices require a distance sensor to correct SOD shifts, which is not practical or efficient.
Innovation Solution
An information processing system that includes a CT device and an information processing apparatus, utilizing a processor to execute steps for acquiring tentatively corrected reconstruction images, calculating sharpness indices, and specifying a correction function to correct SOD shifts without a distance sensor, using a tentative correction function that employs the X-ray generator's angle position and SOD as parameters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a distance sensor is used to correct SOD shifts, then measurement precision is improved, but device complexity and cost increase
Solution Approach 1:
The patent replaces the mechanical/optical distance sensor system with a computational method using image processing and feature point analysis. The SOD correction is achieved through software-based image reconstruction and sharpness evaluation rather than hardware-based distance measurement, eliminating the need for additional sensors while maintaining correction precision.
Solution Approach 2:
The CT device uses its own imaging capability to perform SOD measurement and correction. By analyzing the sharpness of reconstructed images and detecting feature points within the imaging data, the system self-determines the SOD value without requiring external measurement devices, making the system self-sufficient.
2Manufacturing precision
If a distance sensor is installed for SOD correction, then manufacturing precision is improved, but ease of manufacture deteriorates
Solution Approach 1:
The patent eliminates the need for installing and calibrating distance sensors by using a purely computational approach. The SOD correction is derived from image data processing and sharpness analysis, which simplifies the manufacturing process as no additional hardware installation or sensor calibration is required.
3Manufacturing precision
If image sharpness is improved through SOD correction, then manufacturing precision is improved, but device complexity increases
Solution Approach 1:
The system uses its existing imaging and processing capabilities to perform SOD correction. By leveraging the built-in image reconstruction and analysis functions, the system achieves precision improvement without requiring external correction devices, keeping the complexity within the existing system boundaries.
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
Effectively corrects SOD shifts in CT devices without the need for a distance sensor, improving image sharpness and accuracy in reconstruction images.
Implementation Method 1
The X-ray generator is configured to generate a cone beam X-ray toward the sample, and to be rotated around a rotation axis with respect to the sample stage. The detector detects the cone beam X-ray that has transmitted through the sample as measurement data.
Data Source
AI summary
To provide a technique for correcting SOD shifts with no distance sensor for CT devices, and an information processing system for processing information with the CT device. The CT device includes: a sample stage to place a sample; an X-ray generator generating a cone beam X-ray toward the sample and rotated around a rotation axis with respect to the sample stage; and a detector detecting the cone beam X-ray transmitted through the sample as measurement data, The information processing system includes a processor(s) executing: a tentative correction step of acquiring a tentatively corrected reconstruction image for the plural tentative correction parameters from the measurement data, by using a tentative correction function; an index calculation step of calculating an index related to sharpness of each tentatively corrected reconstruction image; and a shift quantity specification step of specifying a correction function of the SOD based on the plural calculated indices.