X-Ray CT High-Quality Image Generation From Single-Scan Data
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Solution Overview
Problem
Existing X-ray CT apparatuses face challenges in reducing noise without increasing exposure, as current methods like adaptive filters cause blurring, and machine learning techniques struggle to prepare ideal learning data sets due to positional deviations and noise modeling difficulties.
Innovation Solution
An X-ray CT apparatus that generates a learned model using machine learning, acquiring one or more learning data sets from a single imaging session by dividing measurement data to create low-quality and high-quality images, allowing for noise reduction without additional exposure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If adaptive filter is used for noise reduction, then noise is reduced, but subject structure becomes blurred
Solution Approach 1:
The patent changes the fundamental parameter of noise reduction from traditional filtering methods to machine learning-based methods. Specifically, it uses denoising autoencoders and other neural network models that learn optimal noise reduction parameters from training data, allowing for noise reduction while preserving structural information that traditional filters blur.
Solution Approach 2:
The patent replaces the mechanical filtering process (adaptive filters) with an information-processing approach using machine learning models. The denoising autoencoder and other neural networks process the projection data or reconstructed images through learned transformations rather than mathematical filtering operations, thereby reducing noise while maintaining structural fidelity.
2Measurement precision
If successive approximation reconstruction is used for noise reduction, then noise is reduced, but spatial resolution for low contrast body decreases and noise texture changes
Solution Approach 1:
The patent introduces multiple parameter changes: using denoising autoencoders instead of iterative reconstruction, applying total variation regularization, and using deep learning models that learn optimal parameters. These changes allow noise reduction while preserving spatial resolution and natural noise texture by learning from training data rather than applying fixed iterative algorithms.
Solution Approach 2:
The patent uses training data that copies the statistical properties and structural characteristics of actual imaging data. By training denoising models on pairs of noisy and clean images (or projection data), the models learn to copy the essential features and textures of the original data while removing noise, thereby preserving spatial resolution and natural appearance.
3Measurement precision
If machine learning is used for noise reduction, then noise reduction effect is improved, but preparation of learning data set becomes difficult
Solution Approach 1:
The patent segments the learning data preparation into manageable components: generating synthetic projection data with controlled noise levels, creating corresponding ground truth images, and organizing them into training sets. This segmentation of the data preparation process makes the complex task of creating machine learning training data systematic and manageable.
Solution Approach 2:
The patent uses copying to create training data by generating synthetic projection data that mimics real imaging conditions. By copying the statistical properties and structural characteristics of actual imaging data into synthetic datasets, the patent creates realistic training data without requiring extensive manual annotation or complex data collection protocols.
4Adaptability or versatility
If same subject is imaged multiple times for machine learning, then learning data set is obtained, but exposure increases and positional deviation occurs
Solution Approach 1:
The patent uses copying to create multiple versions of training data from a single imaging session. By generating synthetic projection data with different noise levels and applying various reconstruction algorithms to create corresponding ground truth images, the patent copies the essential imaging characteristics without requiring repeated physical exposures of the subject.
Solution Approach 2:
The patent segments the acquisition of learning data into computational steps rather than physical imaging steps. By dividing the projection data and creating multiple datasets through computational processing and synthetic generation, the patent obtains diverse training data without increasing the actual X-ray exposure to the subject.
5Measurement precision
If noise is reduced by increasing exposure, then noise is reduced, but exposure to subject increases
Solution Approach 1:
The patent replaces the physical approach of increasing exposure (more X-ray photons) with an information-processing approach using machine learning. The denoising autoencoders and other neural networks process the low-dose projection data or reconstructed images to remove noise computationally, thereby achieving noise reduction without increasing the physical exposure to the subject.
Solution Approach 2:
The patent fundamentally changes the parameter of noise reduction from exposure amount to computational processing. By using deep learning models that learn optimal denoising parameters from training data, the patent achieves noise reduction through information processing rather than physical dose increase, enabling low-dose imaging with high 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 apparatus effectively reduces noise and artifacts in CT images by utilizing machine learning with aligned data sets, achieving high-quality images without the need for repeated exposures.
Implementation Method 1
an X-ray source that irradiates the subject with X-rays and an X-ray detector that detects an X-ray dose transmitted through the subject as the projection data
Data Source
AI summary
Provided is an X-ray CT apparatus including a learned model generated by acquiring one or more learning data sets from one imaging without increasing exposure of a subject, and performing machine learning using the acquired learning set. The learned model is a model after learning in which a low-quality image is input data and a high-quality image is training data. The low-quality image and the high-quality image are obtained based on the same learning measurement data or learning projection data obtained by logarithmically converting the learning measurement data. The low-quality image is a CT image reconstructed from partial data obtained by dividing the learning measurement data or the learning projection data, and the high-quality image is a CT image obtained by reconstructing the learning projection data.


