Spectral CT Material Decomposition via Physics Models

Resolve Bottlenecks,
Find Innovative Solutions
Generate Solutions

Solution Overview

Problem

Current CT technology lacks effective methods for quantitative material decomposition, relying on heuristic dual energy analysis that provides limited explanatory power and can misinterpret material compositions, particularly in distinguishing between soft tissue and bone.

Innovation Solution

A CT system utilizing spectral CT data to decompose projection data into photoelectric and Compton effect images, solving equations based on attenuation coefficients to determine component concentrations, with the option to include K-edge effects for additional components, allowing for precise quantitative material decomposition.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Illumination intensity

If dual energy analysis with subtraction or division of images is used, then material contrast is enhanced, but measurement precision and explanatory power deteriorate due to heuristic methods lacking physical meaning

Engineering Contradiction:
Improvematerial contrastVSAvoidquantitative accuracy
Core Design Contradiction:
Illumination intensityVSMeasurement precision

Solution Approach 1:

The patent replaces the heuristic mechanical image subtraction/division method with a physics-based mathematical model incorporating photoelectric and Compton effect equations. This substitution transforms the arbitrary heuristic approach into a scientifically grounded quantitative analysis that preserves measurement precision while maintaining contrast enhancement capabilities.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent changes the fundamental parameters from simple image intensity values to physics-based attenuation coefficients (photoelectric and Compton). By transforming the data representation to include these physical parameters, the system achieves both high contrast and quantitative accuracy simultaneously.

Inventive Principle:
Principle #35Parameter changes

2Productivity

If soft tissue and bone equivalence decomposition is used, then two material images are obtained, but reliability deteriorates because high values do not indicate actual bone presence

Engineering Contradiction:
Improvedecomposition speedVSAvoidmaterial identification accuracy
Core Design Contradiction:
ProductivityVSReliability

Solution Approach 1:

The patent segments the total attenuation into distinct physical effect components (photoelectric and Compton) rather than using a single equivalence model. This segmentation allows each component to be analyzed independently, providing reliable material identification based on the unique signature of each physical effect rather than ambiguous equivalence values.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent introduces physical effect models as intermediary layers between the raw attenuation data and material identification. These intermediary models act as translators that convert measured attenuation into physically meaningful parameters, enabling reliable distinction between different materials based on their unique interaction characteristics with X-rays.

Inventive Principle:
Principle #24Intermediary (Mediator)

3Measurement precision

If spectral CT data with multiple physical effects is analyzed, then quantitative decomposition of multiple components is enabled, but device complexity increases

Engineering Contradiction:
Improvecomponent concentration accuracyVSAvoiddata processing complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent extracts and separates the contributions of different physical effects (photoelectric and Compton) from the total attenuation measurement. By isolating these individual effects through mathematical decomposition, the system can quantify multiple components simultaneously while managing complexity through focused analysis of distinct physical phenomena rather than treating the total attenuation as a single complex signal.

Inventive Principle:
Principle #2Taking out (Extraction)

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

This approach enhances the quality and accuracy of material decomposition, enabling precise determination of component concentrations in regions of interest, even with multiple components, by leveraging spectral CT data and physical models of attenuation effects.

Implementation Method 1

a physical model of the object. The physical model contains several physical effects such as Compton effect, photoelectric effect and K-edge effect

Methodology Applied
Scientific EffectPhotoelectric effect: Photoelectric Effect

Implementation Method 2

a physical model of the object. The physical model contains several physical effects such as Compton effect, photoelectric effect and K-edge effect

Methodology Applied
Scientific EffectCompton scattering: Compton Scattering

Implementation Method 3

a modeling unit for obtaining a photoelectric effect projection data set and a Compton effect projection data set by decomposing said spectral CT projection data set by means of respective models of photoelectric effect and Compton effect

Methodology Applied
Scientific EffectPhotoelectric effect: Photoelectric Effect

Implementation Method 4

a modeling unit for obtaining a photoelectric effect projection data set and a Compton effect projection data set by decomposing said spectral CT projection data set by means of respective models of photoelectric effect and Compton effect

Methodology Applied
Scientific EffectCompton scattering: Compton Scattering

Implementation Method 5

a reconstruction unit for reconstructing a photoelectric effect image and a Compton effect image of said region of interest from said photoelectric effect projection data set and Compton effect projection data set

Methodology Applied
Scientific EffectTomography: Tomography

Data Source

PatentUS7627080B2Quantitative material decomposition for spectral CT
Publication Date: 2009.12.01 KONINKLIJKE PHILIPS NV
  • US7627080B2 patent drawing
  • US7627080B2 patent drawing
  • US7627080B2 patent drawing

AI summary

A data processing method for use in an imaging system is described. The method includes determining a special footprint of an unknown mixture of substances from a first region and using the spectral footprint to decomposition of second region.