Single-Energy CT Electron Density Mapping via Synthetic Monochromatic Data
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Solution Overview
Problem
Conventional methods for determining electron density in radiation therapy using CT images are limited in accuracy due to radiation hardening effects, especially when using polychromatic X-radiation, and not all CT systems have the capability for dual-energy recordings.
Innovation Solution
A method and device for determining spatial distribution of material properties like electron density using single-energy CT systems, which involves capturing measurement projection data, reconstructing image data, and estimating the distribution of basic materials using a threshold value, allowing for accurate material property determination independent of radiation energy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional CT mapping methods are used to determine electron density, then the process is simple and fast, but the accuracy is limited due to radiation hardening effects
Solution Approach 1:
The patent changes the parameter of X-ray energy from polychromatic (conventional) to monochromatic (synthetic), eliminating radiation hardening effects and enabling accurate electron density determination with simple CT systems
Solution Approach 2:
The patent creates a synthetic monochromatic projection data set that copies the essential features of dual-energy data, allowing single-energy CT systems to achieve dual-energy accuracy without additional hardware
2Measurement precision
If dual-energy CT is used to determine electron density accurately, then measurement precision improves, but device complexity and availability decrease
Solution Approach 1:
The patent makes single-energy CT systems universal by enabling them to perform electron density determination with dual-energy accuracy through synthetic monochromatic projection data, eliminating the need for specialized dual-energy hardware
3Productivity
If polychromatic X-radiation is used in CT recording, then the recording process is simple and fast, but radiation hardening causes inaccuracies in electron density determination
Solution Approach 1:
The patent replaces the physical dual-energy measurement system with a computational approach using synthetic monochromatic projection data, maintaining fast single-energy recording while achieving accurate electron density determination through image processing
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
Enables precise determination of material properties, such as electron density, in examination regions, facilitating accurate radiation therapy planning without the need for dual-energy CT systems, even in simpler or older CT systems, maintaining high accuracy comparable to dual-energy systems.
Implementation Method 1
The Compton effect is dominant when radiation is absorbed in the soft tissue
Implementation Method 2
the photoelectric effect is dominant in the case of absorption in solid body matter, such as e.g. bone matter
Implementation Method 3
Image data is then reconstructed on the basis of the captured measurement projection data
Data Source
AI summary
A method is for determining a spatial distribution of a material property value in an examination region of an examination object. According to an embodiment, the method includes capturing measurement projection data; reconstructing image data based upon the captured measurement projection data; estimating a distribution of two basic materials using a threshold value by classifying image points; determining a distribution of the two basic materials based upon the estimated distribution and a general dependency rule; and determining a spatial distribution of the material property value, independent of the measurement energy, based upon the determined distribution and based upon a previously known theoretical relationship between the distribution of the material property value and a distribution of the two basic materials. In addition, a material property distribution determining device is described in one embodiment, and a computer tomography system is also described in another embodiment.