Adaptive Metal Artifact Correction in CT Imaging
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Solution Overview
Problem
Current metal artifact reduction (MAR) algorithms in CT images often fail to completely eliminate artifacts, sometimes introducing new ones due to their limitations in correcting image distortions caused by high-density objects like metal implants.
Innovation Solution
An adaptive image correction apparatus that utilizes a correction sampler, comparator, and artifact correction controller to re-apply corrective actions from a 'corrector image' to the initial image, weighing the actions based on compensatory degrees between image neighborhoods to ensure effective artifact removal without creating new artifacts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If metal artifact reduction algorithms are applied to CT images, then image artifacts are reduced, but new artifacts are occasionally created
Solution Approach 1:
The patent applies a preliminary correction step using a correction image generated from the initial CT image and metal mask. This preliminary correction identifies and records artifact patterns before the final adaptive application, allowing the system to learn what corrections are needed without yet applying them globally, thus avoiding the creation of new artifacts from premature aggressive correction
Solution Approach 2:
The patent implements local quality by computing adaptive weights for each image point based on local image characteristics and compensation feasibility. The corrective action is applied with different weights at different locations - fully applied where safe, attenuated where risky - making the correction quality spatially variable rather than uniform, thus removing artifacts where beneficial while avoiding new artifacts where harmful
2Object-affected harmful factors
If corrective action is applied globally to remove artifacts, then existing artifacts are removed, but new artifacts may be created in regions where correction is not compensable
Solution Approach 1:
The patent uses feedback by comparing the initial image with the correction image to compute adaptive weights. The system continuously evaluates whether correction is compensable at each location based on local image characteristics, using this feedback information to modulate the corrective action. This closed-loop approach ensures corrections are applied only where reliable, maintaining high correction reliability while still removing existing artifacts
Solution Approach 2:
The patent makes the correction system dynamic by computing weights that adapt to local image conditions. Rather than applying a static correction globally, the system dynamically adjusts the corrective action at each image point based on local compensability, making the correction process flexible and responsive to local conditions, thus ensuring reliability while removing artifacts
3Object-generated harmful factors
If adaptive weighting is applied to corrective action, then new artifact creation is avoided, but correction accuracy may be reduced in regions where full correction is safe
Solution Approach 1:
The patent changes the parameter of corrective action strength from a fixed global value to a spatially varying parameter determined by adaptive weights. By modifying this parameter locally based on compensation feasibility, the system optimizes correction accuracy in safe regions (using full correction) while preventing new artifacts in risky regions (using attenuated correction), thus resolving the contradiction between accuracy and artifact prevention
Data Source
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AI summary
An apparatus for and a method of correcting an image for an image artifact. An initial image is corrected by an image artifact corrector (190). The so corrected sample correction image is compared with the initial image to obtain information on the corrective action. The corrective action is then adaptively reapplied by a controller (140) to obtain an improved corrected image thereby ensuring previously present artifacts are removed and creation of new artifacts are avoided.