X-ray CT Dual Energy Image Segmentation for Contrast and Noise
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Solution Overview
Problem
Conventional X-ray CT systems face challenges in obtaining dual energy images with improved signal-to-noise ratio (S/N) and contrast due to the degradation of S/N in the weighted subtraction process.
Innovation Solution
An X-ray CT apparatus and image processing method that applies both high and low energy X-rays to a subject, acquiring projection data for image reconstruction, determining difference information, segmenting images into pixel areas, and using a weighted subtraction process to enhance S/N and contrast, with adjustable segment conditions for various substances.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a weighted subtraction process is applied to obtain dual energy images, then contrast between substances is enhanced, but signal-to-noise ratio (S/N) is degraded
Solution Approach 1:
The patent segments the image into multiple pixel areas based on difference information between first and second X-ray images. By dividing the image into distinct regions (e.g., bone, soft tissue, air), the system can apply different processing strategies to each segment, preserving contrast enhancement while reducing noise through localized analysis rather than global subtraction.
Solution Approach 2:
The patent applies local quality by setting different pixel values for different pixel areas based on their material composition. Instead of uniform processing, each pixel area is assigned appropriate CT values or weighting factors according to its specific characteristics (bone, soft tissue, air), thereby optimizing both contrast and noise performance locally.
2Measurement precision
If dual energy imaging is performed using weighted subtraction, then substance differentiation is improved, but image quality is compromised due to noise
Solution Approach 1:
The system segments pixel areas based on difference information and applies different CT values or weighting factors to each segment. This allows bone, soft tissue, and air regions to be processed differently, enhancing substance differentiation while maintaining image quality through region-specific optimization.
Solution Approach 2:
The patent changes parameters (CT values, weighting factors) based on the material composition of different pixel areas. By adjusting these parameters according to whether the region contains bone, soft tissue, or air, the system optimizes both substance differentiation capability and 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
The method effectively improves the S/N and contrast of dual energy images, allowing for better differentiation and visualization of substances within the subject.
Implementation Method 1
X-ray absorption coefficients of substances in a subject are different depending on the X-rays different in energy spectrum
Data Source
AI summary
An X-ray CT apparatus includes an X-ray radiation unit which applies a first X-ray having a first energy spectrum and a second X-ray having a second energy spectrum different from the first energy spectrum to a subject, an X-ray data acquisition unit which acquires first X-ray projection data of the subject based on the first X-ray and second X-ray projection data of the subject based on the second X-ray, and an image reconstruction unit which determines information about a difference between the first X-ray and the second X-ray with respect to an image of the subject, segments the image into at least two pixel areas based on the difference information, and sets part of the segmented pixel areas to a dual energy image obtained by a weighted subtraction process based on X-ray projection data having a plurality of energy spectrums.