K-edge Imaging Spectral CT Sensitivity
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional computed tomography (CT) systems do not effectively utilize spectral characteristics for K-edge imaging, particularly for elements like iodine, due to beam hardening issues, which limits the sensitivity of K-edge imaging.
Innovation Solution
An imaging system that emits poly-chromatic radiation and uses an energy-resolving detector to discriminate signals based on multiple energy thresholds corresponding to different K-edge energies of elements in a contrast agent, allowing for the decomposition and reconstruction of multi K-edge images, thereby enhancing sensitivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If conventional CT systems use polychromatic radiation for imaging, then the imaging coverage and penetration are improved, but beam hardening occurs which reduces K-edge imaging sensitivity
Solution Approach 1:
The patent segments the polychromatic radiation spectrum into multiple energy bins using an energy-resolving photon counting detector. By dividing the energy spectrum into discrete bins and processing each bin separately, the system can identify K-edge discontinuities at specific energy thresholds while maintaining the benefits of polychromatic radiation for overall imaging coverage.
Solution Approach 2:
The patent changes the parameter of energy resolution by using an energy-resolving detector that can distinguish photons at different energy levels. This allows the system to detect the abrupt changes in attenuation coefficient at K-edge energies (e.g., 33.2 keV for iodine, 50.2 keV for gadolinium) even within the polychromatic spectrum, thereby maintaining K-edge sensitivity while using polychromatic radiation.
2Measurement precision
If energy-resolving photon counting detectors are used to detect spectral information, then K-edge imaging sensitivity is improved, but the device complexity increases
Solution Approach 1:
The patent replaces conventional energy-integrating detectors with energy-resolving photon counting detectors. This substitution enables the detection of individual photon energies and their distribution across multiple bins, providing spectral information necessary for K-edge imaging. The electronic processing of photon counts in different energy bins achieves spectral resolution without mechanical moving parts.
3Ease of operation
If spectral information is integrated over the energy spectrum in conventional detectors, then the signal output is simplified, but the spectral characteristics including K-edge information are lost
Solution Approach 1:
Instead of integrating all photon energies into a single signal, the patent segments the energy spectrum into multiple bins and counts photons in each bin separately. This segmentation preserves the spectral distribution information, allowing the system to identify K-edge discontinuities by analyzing the photon count distribution across different energy thresholds while maintaining relatively simple processing through linear algebra operations.
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
The system improves the sensitivity of K-edge imaging by accurately distinguishing and reconstructing the elemental composition, even in high-attenuation scenarios, using a contrast agent with known stoichiometric ratios and K-edge energies, providing a unique fingerprint for the elements.
Implementation Method 1
The x-ray tube rotates around an examination region located between the x-ray tube and the one or more detectors and emits polychromatic radiation
Implementation Method 2
A spectral CT system may include an energy resolving photon counting detector such as a direct conversion CZT detector (or CdTe, Si, GaAs, etc) that produces an electrical signal for each photon that it detects, wherein the electrical signal is indicative of the energy of that photon
Implementation Method 3
The system further includes an energy discriminator that energy resolves the signal based on a plurality of different energy thresholds, wherein at least two of the energy thresholds have values correspondable to at least two different K-edge energies of two different elements in a mixture
Implementation Method 4
The system also includes a signal decomposer that decomposes the energy-resolved signal into at least a multi K-edge component representing the at least two different K-edge energies to which the values of the at least two energy thresholds are correspondable
Implementation Method 5
K-edge imaging leverages the fact that high-Z elements tend to attenuate photons to a much higher extent above a particular energy, the K-edge energy of the given element, relative to attenuating photons just below the K-edge energy
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
An imaging system including a radiation source (110) that emits poly-chromatic radiation that traverses an examination region and a detector (116) that detects radiation traversing the examination region and produces a signal indicative of the energy of a detected photon. The system further includes an energy discriminator (122) that energy resolves the signal based on a plurality of different energy thresholds, wherein at least two of the energy thresholds have values corresponding to at least two different K-edge energies of two different elements in a mixture disposed in the examination region. The system also includes a signal decomposer (132) that decomposes the energy-resolved signal into at least a multi K-edge component representing the at least two different K-edge energies. In one instance, a stoichiometric ratio of the two different elements in the contrast agent is known and substantially constant.