Adaptive Soft Tissue Thresholding for Cone-Beam CT Artifact Reduction

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Solution Overview

Problem

Current cone-beam CT imaging techniques face challenges in effectively reducing artifacts caused by soft tissue, particularly due to the difficulty in setting appropriate threshold values for soft tissue segmentation, which affects the efficiency of artifact correction.

Innovation Solution

An adaptive artifact reduction method using a roughness function based on weighting values applied to streak-only images, allowing for automatic determination of optimal weighting values to minimize artifacts in the final image, thereby improving soft tissue artifact correction without the need for experimental variations in segmentation and forward/back-projection processes.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If fixed thresholds are used for soft tissue segmentation, then the segmentation process is simple and fast, but the artifact correction accuracy deteriorates due to inability to adapt to varying soft tissue levels

Engineering Contradiction:
Improvesegmentation processing speedVSAvoidartifact correction accuracy
Core Design Contradiction:
ProductivityVSManufacturing precision

Solution Approach 1:

The patent applies dynamics by transitioning from fixed static thresholds to adaptive dynamic thresholds. The system calculates optimal thresholds dynamically based on the specific image characteristics and soft tissue distributions in each scan, allowing the segmentation parameters to adapt to varying conditions while maintaining processing efficiency through automated calculation.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The patent implements parameter changes by modifying the threshold values used for soft tissue segmentation. Instead of using predetermined fixed thresholds, the system adjusts threshold parameters based on image analysis, enabling accurate separation of soft tissue from other structures while maintaining computational efficiency through automated parameter optimization.

Inventive Principle:
Principle #35Parameter changes

2Manufacturing precision

If experimental variations of soft tissue level in segmentation are performed, then the optimal threshold can be found, but the processing time and complexity increase significantly

Engineering Contradiction:
Improvethreshold determination accuracyVSAvoidprocessing time
Core Design Contradiction:
Manufacturing precisionVSLoss of time

Solution Approach 1:

The patent applies preliminary action by performing preliminary segmentation and analysis to identify soft tissue regions before final artifact correction. This preliminary step establishes a foundation for determining optimal thresholds without requiring extensive experimental variations, reducing overall processing time while maintaining accuracy.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The system implements self-service through automated threshold optimization algorithms that independently determine optimal segmentation parameters without requiring manual experimental adjustments. The algorithm automatically analyzes image characteristics and computes optimal thresholds, eliminating time-consuming manual trial-and-error processes.

Inventive Principle:
Principle #25Self-service

3Manufacturing precision

If multiple weighted streak-only images are subtracted with different weighting values, then the artifact reduction quality improves, but the computational complexity increases

Engineering Contradiction:
Improveartifact reduction qualityVSAvoidcomputational complexity
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

The patent applies dynamics by implementing adaptive weighting value selection. Instead of using multiple fixed weighting values requiring complex computations, the system dynamically determines optimal weighting values based on image characteristics and roughness function analysis, achieving high artifact reduction quality while reducing computational complexity through adaptive parameter selection.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The system implements feedback through the roughness function evaluation mechanism. The roughness function provides feedback on image quality after artifact reduction, allowing the system to iteratively optimize weighting values and segmentation parameters. This feedback-driven approach ensures high artifact reduction quality while avoiding unnecessary computational complexity by stopping optimization when optimal results are achieved.

Inventive Principle:
Principle #23Feedback

Data Source

PatentEP1941458B1Automatic adaptive soft tissue thresholding for two-pass CT cone-beam artifact reduction
Publication Date: 2018.08.29 PHILIPS INTPROP & STANDARDS GMBH
  • EP1941458B1 patent drawingFigure 1
  • EP1941458B1 patent drawingFigure 2
  • EP1941458B1 patent drawingFigure 3~6

AI summary

Since the soft tissue levels in an image usually comprise a variety of values between air and bone boundaries, it may not be obvious a priori what threshold value applies. According to an exemplary embodiment of the present invention, an examination apparatus is provided which is adapted for determining the optimal weight for subtraction of a soft tissue correction image without performing a multitude of forward and backward projections. This may be provided determining a roughness function based on a plurality of subtractions of the soft tissue streak image, each subtraction corresponding to a different weighting of the streak image.