X-ray CT Image Reconstruction Scattered Ray Correction
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Solution Overview
Problem
Existing X-ray CT apparatuses face challenges in achieving high image quality due to the presence of scattered ray components, which degrade the quality of reconstructed images, especially in cone beam CT systems where the large angle of view exacerbates this issue.
Innovation Solution
The X-ray CT apparatus calculates and considers the scattered ray component in each three-dimensional space by accounting for atom number density and atomic number, allowing for accurate reconstruction of tomographic images by subtracting the estimated scattered ray component from the detected X-ray data.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional image reconstruction is performed without considering scattered rays, then the reconstruction process is simple and fast, but the image quality is degraded due to scattered ray components
Solution Approach 1:
The irradiation target is divided into multiple three-dimensional spaces (voxels) with different atom number densities and atomic numbers. This segmentation allows the scattered ray component to be calculated and removed for each voxel, improving image quality by addressing scattered rays locally rather than applying a simple global correction.
2Measurement precision
If scattered ray correction is performed using simple methods, then the processing time is short, but the image quality improvement is limited
Solution Approach 1:
The patent changes the parameters used for scattered ray correction from simple uniform assumptions to voxel-specific parameters including atom number density and atomic number. This allows more accurate scattered ray component calculation and removal, significantly improving image quality despite the increased processing complexity.
3Area of stationary object
If cone beam CT with large angle of view is used, then the field of view is expanded, but the impact of scattered ray components is exacerbated
Solution Approach 1:
The patent applies local quality correction by calculating and removing scattered ray components for each voxel based on its specific atom number density and atomic number. This localized approach allows the system to maintain the large field of view advantage of cone beam CT while correcting scattered ray effects that vary throughout the imaging volume, thereby improving overall image quality.
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 significantly improves the image quality of CT images by accurately accounting for scattered rays, particularly in cone beam CT systems, where the impact of scattered components is most pronounced, leading to a more precise and clearer reconstruction of images.
Implementation Method 1
an X-ray irradiation unit that rotates around a placement portion on which an irradiation target is placed and emits X-rays; an X-ray detection unit that detects the X-rays emitted from the X-ray irradiation unit and passed through the irradiation target
Implementation Method 2
the image reconstruction unit calculates a scattered ray component scattered in each of a plurality of three-dimensional spaces obtained by partitioning the irradiation target by a predetermined size among the X-rays detected by the X-ray detection unit in consideration of an atom number density per unit volume in each of sections included in the plurality of three-dimensional spaces and an atomic number
Data Source
AI summary
Provided is an X-ray CT apparatus including an X-ray irradiation unit that rotates around a placement portion on which an irradiation target is placed and emits X-rays; an X-ray detection unit that detects the X-rays emitted from the X-ray irradiation unit and passed through the irradiation target; and an image reconstruction unit that reconstructs a tomographic image of the irradiation target based on image data of the X-rays detected by the X-ray detection unit, in which the image reconstruction unit calculates a scattered ray component scattered in each of a plurality of three-dimensional spaces obtained by partitioning the irradiation target by a predetermined size among the X-rays detected by the X-ray detection unit in consideration of an atom number density per unit volume in each of sections included in the plurality of three-dimensional spaces and an atomic number, and reconstructs the tomographic image in consideration of the scattered ray component.