X-ray CT Image Reconstruction with Dose-Adaptive Quality Improvement
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Solution Overview
Problem
Existing X-ray CT systems face challenges in maintaining consistent image quality when reconstructing images from projection data obtained with varying X-ray doses, leading to image quality variations across different phases.
Innovation Solution
An X-ray CT apparatus and image processing device that modulate the X-ray dose based on predetermined dose modulation data, using a reference dose to select an appropriate image quality improvement process from a stored table, ensuring equivalent image quality across all sections by adjusting the image quality improvement process based on the ratio of the reference dose to the actual dose during imaging.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If dose modulation is applied to reduce radiation exposure, then radiation dose is reduced, but image quality deteriorates in low dose phases
Solution Approach 1:
The patent applies parameter changes by modifying the X-ray dose parameter according to heartbeat phase, using high dose during diastolic phase (low motion) and low dose during systolic phase (high motion). This resolves the contradiction by accepting variable image quality across phases while reducing overall radiation exposure, with the understanding that high-dose phases provide sufficient image quality for diagnostic purposes.
Solution Approach 2:
The patent applies local quality by providing different dose levels for different temporal regions (heartbeat phases) rather than uniform dosing. High dose is applied locally to phases requiring better image quality (diastolic), while low dose is applied to phases where motion artifacts are less critical (systolic), optimizing the balance between radiation exposure and image quality.
2Manufacturing precision
If image quality improvement process is applied to low dose phase images, then image quality is improved, but processing complexity increases
Solution Approach 1:
The patent applies self-service by implementing automatic selection of image quality improvement processes based on dose phase classification. The system autonomously determines which low-dose phases require processing and selects appropriate improvement algorithms without operator intervention, reducing processing complexity while maintaining image quality improvement benefits.
Solution Approach 2:
The patent applies segmentation by dividing the image processing task into distinct phases: dose phase classification, identification of low-dose phases requiring improvement, and application of appropriate improvement processes. This segmented approach reduces overall processing complexity by handling each aspect separately rather than applying a single complex process to all images.
3Adaptability or versatility
If operator judgment is used to determine image quality improvement intensity, then flexibility is maintained, but operator dependency increases
Solution Approach 1:
The patent applies feedback by using the classified dose phase information as feedback to automatically determine the intensity of image quality improvement processes. The system monitors the dose phase, identifies low-dose phases, and automatically adjusts processing intensity accordingly, maintaining flexibility through adaptive processing while eliminating operator dependency for routine decisions.
Solution Approach 2:
The patent applies self-service by enabling the system to automatically perform the entire workflow of dose phase classification, identification of images requiring improvement, and selection of appropriate processing intensities without operator intervention. This maintains adaptability through automated decision-making while significantly reducing operator dependency.
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 solution enables consistent image quality across all sections by automatically selecting the optimal image quality improvement process, eliminating the need for operator-dependent decisions and maintaining image quality equivalent to high-dose phases while reducing radiation exposure.
Implementation Method 1
an X-ray source that irradiates an object with X-rays; an X-ray detector that is disposed to oppose the X-ray source and detects X-rays having been transmitted through the object
Data Source
AI summary
An X-ray CT apparatus 1 stores an image quality improvement table 3 indicating levels of image quality improvement effects for a plurality of image quality improvement processes in a storage device 123. In a case where imaging is performed while modulating an X-ray irradiation amount on the basis of predetermined dose modulation data, an image processing device 122 acquires a reference dose used as a reference of image quality, and acquires an irradiation X-ray dose during imaging for image reconstruction target projection data from the dose modulation data. The image processing device 122 determines an image quality improvement process for obtaining image quality used as a reference by referring to the image quality improvement table 3 on the basis of a ratio between the dose values, and performs the determined image quality improvement process on the reconstruction target projection data.