Image Domain De-noising Using Huber Roughness Penalty Minimization

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Solution Overview

Problem

Current image reconstruction algorithms in CT scanners, such as iterative reconstruction (IR) and image domain de-noising methods, face challenges in efficiently reducing noise while maintaining image quality and minimizing radiation exposure, with IR algorithms being computationally expensive and image domain algorithms providing limited results.

Innovation Solution

An image data processing component employing image domain only iterative de-noising algorithms based on Huber roughness penalty minimization, which de-noises reconstructed image data solely in the image domain, reducing computational expense and noise while preserving edges, using a processor to execute algorithms that minimize the Huber roughness penalty.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If iterative reconstruction (IR) algorithms are used to reduce noise and improve image quality, then image quality and diagnostic value are improved, but computational expense and processing time increase significantly

Engineering Contradiction:
Improveimage qualityVSAvoidprocessing speed
Core Design Contradiction:
Manufacturing precisionVSProductivity

Solution Approach 1:

The patent segments the de-noising process into two distinct stages: (1) an initial filtered backprojection reconstruction to generate a preliminary image, and (2) a subsequent image domain de-noising step using Huber roughness penalty minimization. This segmentation allows the computationally intensive IR to be replaced with a faster image domain method while preserving the benefits of iterative reconstruction through the two-stage approach.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent extracts the de-noising function from the projection domain (where iterative reconstruction operates) and relocates it to the image domain. By applying Huber roughness penalty minimization directly to the reconstructed image data rather than to projection data, the method achieves comparable noise reduction with significantly reduced computational expense.

Inventive Principle:
Principle #2Taking out (Extraction)

2Object-affected harmful factors

If iterative reconstruction (IR) algorithms are used to reduce noise, then noise reduction is achieved, but radiation dose cannot be reduced due to computational constraints

Engineering Contradiction:
Improveimage noiseVSAvoidprocessing efficiency
Core Design Contradiction:
Object-affected harmful factorsVSProductivity

Solution Approach 1:

The patent employs a computationally inexpensive image domain de-noising method (Huber roughness penalty minimization) as a disposable alternative to the expensive iterative reconstruction process. This lighter-weight algorithm achieves sufficient noise reduction without requiring the heavy computational resources of full IR, enabling its use in resource-constrained environments.

Inventive Principle:
Principle #27Cheap short-living objects (Disposable)

3Productivity

If traditional image domain de-noising algorithms are used, then processing speed is improved, but noise reduction effectiveness is limited compared to IR algorithms

Engineering Contradiction:
Improveprocessing speedVSAvoidnoise reduction effectiveness
Core Design Contradiction:
ProductivityVSManufacturing precision

Solution Approach 1:

The patent changes the mathematical parameters and objective function used in image domain de-noising by implementing Huber roughness penalty minimization. This parameter change transforms a simple smoothing operation into a more sophisticated de-noising process that better preserves edges and structures while effectively reducing noise, achieving results comparable to iterative reconstruction.

Inventive Principle:
Principle #35Parameter changes

4Manufacturing precision

If Huber roughness penalty minimization is applied in the projection domain (iterative reconstruction), then optimal noise reduction is achieved, but computational complexity increases due to repeated switching between image and projection domains

Engineering Contradiction:
Improvenoise reduction qualityVSAvoidalgorithm complexity
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

The patent extracts the Huber roughness penalty minimization operation from the iterative reconstruction loop in the projection domain and applies it independently in the image domain. This extraction eliminates the need for repeated forward and back-projections, reducing algorithmic complexity while maintaining the noise reduction quality benefits of Huber penalty minimization.

Inventive Principle:
Principle #2Taking out (Extraction)

Data Source

PatentUS9159122B2Image domain de-noising
Publication Date: 2015.10.13 KONINKLIJKE PHILIPS NV
  • US9159122B2 patent drawing
  • US9159122B2 patent drawing
  • US9159122B2 patent drawing

AI summary

An image data processing component (122) includes algorithm memory (212) including one or more image domain only iterative de-noising algorithms (214) based on the Huber roughness penalty minimization and a processor (206) which de-noises reconstructed image data solely in the image domain based on at least one of the Huber roughness penalty iterative minimization algorithms.