Spectral CT Detector Transient Correction
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Solution Overview
Problem
The generation of energy-dependent projection values in spectral computed tomography systems is temporally instable, leading to reduced image quality due to transient behavior in energy-resolving detectors, which affects the accuracy of reconstructed computed tomography images.
Innovation Solution
A correction device and method that determine a transient behavior parameter based on energy-dependent calibration projection values to correct energy-dependent actual projection values, using a decomposition algorithm to improve the quality of these values by accounting for detector behavior over time and material thicknesses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of information
If energy-dependent projection values are generated using an energy-resolving detector, then spectral information is obtained, but temporal instability occurs due to transient detector behavior
Solution Approach 1:
The system performs preliminary calibration measurements to characterize the transient behavior of the energy-resolving detector before actual scanning. By pre-determining correction factors based on known phantom measurements taken under controlled conditions, the system prepares correction data in advance that accounts for detector transient effects, thereby maintaining spectral information while compensating for temporal instability during actual imaging
Solution Approach 2:
The system implements a feedback mechanism where correction factors are calculated based on measured transient behavior and applied to correct the projection values. The correction process uses the relationship between measured projection values and known phantom composition to determine and apply appropriate correction factors, creating a closed-loop system that compensates for detector transient effects while preserving spectral information
2Measurement precision
If correction factors are applied to compensate for transient behavior, then projection value quality improves, but correction complexity increases
Solution Approach 1:
The system transforms the correction problem into a parameter optimization task by determining correction factors that maximize the consistency between measured projection values and known phantom properties. By formulating the correction as a parameter determination problem based on statistical relationships between measurements and known quantities, the system achieves accurate correction without requiring complex physical models of the detector transient behavior
Solution Approach 2:
The system introduces correction factors as intermediary parameters that mediate between the raw measured projection values and the corrected values. These correction factors serve as a simplified representation of the complex transient detector behavior, allowing the system to compensate for temporal instability through simple multiplicative or additive corrections rather than complex real-time processing
3Measurement precision
If calibration measurements are performed for different materials and thicknesses, then correction accuracy improves, but calibration time increases
Solution Approach 1:
The system performs comprehensive calibration measurements using phantoms with different materials and thicknesses to create a universal correction framework. By characterizing detector transient behavior across a range of conditions during calibration, the system establishes correction factors that can be applied universally during actual scanning without requiring material-specific or thickness-specific corrections, thereby achieving high correction accuracy while keeping calibration procedures practical
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 correction method significantly improves the quality of energy-dependent projection values by reducing the influence of transient detector behavior, leading to enhanced material-dependent projection values and improved computed tomography image reconstruction.
Implementation Method 1
an energy-resolving detector for generating energy-dependent projection values based on the radiation
Implementation Method 2
a transient behavior determination and correction unit for determining a transient behavior parameter being indicative of a transient behavior of the energy-resolving detector
Data Source
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AI summary
The invention relates to a correction device for correcting energy-dependent projection values. A projection values providing unit (13) provides energy-dependent calibration projection values, which have been generated, during a calibration procedure, based on radiation, which has traversed a material and impinged on an energy-resolving detector (6), for a) different times after the intensity of the radiation has changed in the calibration procedure, b) different intensity changes and c) different materials and/or different material thicknesses. A transient behavior determination and correction unit (12) determines a transient behavior of the energy-resolving detector based on the energy-dependent calibration projection values and corrects energy-dependent actual projection values based on the determined transient behavior. The corrected energy-dependent actual projection values are less influenced or not influenced at all by the transient behavior of the energy-resolving detector, thereby improving the quality of the energy-dependent actual projection values.