Tomogram Noise Reduction via Edge-Adaptive Filtering
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing methods for correcting stray radiation artifacts in computed tomography (CT) scans reduce the signal-to-noise ratio, leading to increased image noise and loss of detailed structure information in tomograms and volume renderings.
Innovation Solution
A method that selectively smooths noise in tomograms corrected for stray radiation using an adaptive filter based on the edge profile of the object, generating a smoothing mask to control the degree of smoothing for different voxels, and forms a noise-reduced tomogram by subtracting a filtered artifact map from the original tomogram.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If subtraction-based stray radiation correction is applied to projection images, then stray radiation artifacts are reduced, but signal-to-noise ratio decreases and image noise increases
Solution Approach 1:
The patent applies different smoothing strengths to different regions of the image based on local structure characteristics. Edge regions receive minimal smoothing to preserve structural information, while homogeneous regions receive stronger smoothing to reduce noise. This local differentiation resolves the contradiction by adapting the noise reduction intensity to the specific needs of each image region.
Solution Approach 2:
The patent dynamically adjusts the smoothing parameter (filter strength) based on the local image characteristics, particularly the edge profile. By changing the smoothing parameter from region to region, the method achieves both artifact reduction in homogeneous areas and noise preservation in structurally important areas, thereby resolving the SNR degradation problem.
2Object-affected harmful factors
If subtraction-based stray radiation correction is applied to projection images, then stray radiation artifacts are reduced, but detailed structure information is lost
Solution Approach 1:
The patent identifies edge regions containing detailed structure information and applies minimal smoothing to these areas, while applying stronger smoothing only to homogeneous regions without important structures. This selective approach preserves detailed structure information while still reducing artifacts in appropriate regions.
Solution Approach 2:
The patent performs preliminary edge detection and classification before applying the smoothing filter. By identifying and marking edge regions in advance, the method ensures that subsequent noise reduction does not compromise important structural information, thereby preventing information loss before it occurs.
3Reliability
If uniform smoothing is applied to correct stray radiation, then noise is reduced, but edge sharpness and structural detail are degraded
Solution Approach 1:
The patent implements spatially varying smoothing where the filter strength is modulated according to the local edge profile. Regions with strong edges maintain sharp boundaries with minimal smoothing, while homogeneous regions receive aggressive smoothing for noise reduction. This local adaptation resolves the contradiction between noise reduction and edge preservation.
Solution Approach 2:
The patent makes the smoothing filter dynamic by adjusting its parameters based on local image characteristics detected in real-time. The filter adapts its strength and characteristics to match the local structure, being more aggressive in homogeneous areas and more conservative near edges, thereby dynamically balancing noise reduction and edge sharpness.
Data Source
AI summary
A method is provided for reducing noise in a tomogram and/or volume rendering of at least one object. The noise can occur when scattered radiation artifacts are corrected. At least one tomogram that is affected by scattered radiation and at least one preliminary tomogram that has been corrected by a defined correction method are produced from a plurality of projection image datasets that are affected by scattered radiation. The noise emerging when scattered radiation artifacts are corrected may be reduced by selectively smoothening the noise using a filter based on an edge contour of the at least one object, which contour is rendered in the tomogram that is affected by scattered radiation.