X-Ray Tube Current Estimation Using Dual kVp Plateau Calibration
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Solution Overview
Problem
Existing methods struggle to accurately determine X-ray tube current during fast kVp switching in spectral CT imaging due to rapid changes and system variations, making timely and precise emission current measurement challenging.
Innovation Solution
A computer-implemented method involving a calibration phase to determine a calibration factor based on the ratio of tube currents at different kVp plateaus, allowing accurate estimation of tube current during fast kVp switching by using a closed-loop control system to adapt filament current and focal spot position.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If fast kVp switching is used for spectral CT imaging, then spectral imaging capability is improved, but tube current measurement accuracy deteriorates due to rapid changes and system variations
Solution Approach 1:
The system performs a calibration phase before actual spectral imaging to pre-determine a calibration factor. This preliminary action stores the relationship between tube current and measured signal under known conditions, enabling accurate current determination during fast kVp switching without real-time measurement delays.
Solution Approach 2:
The invention introduces a calibration factor as an intermediary parameter that mediates between the measured signal and the actual tube current. This calibration factor, determined during a calibration phase, allows indirect but accurate determination of tube current during fast kVp switching when direct measurement is unreliable.
2Loss of time
If direct tube current measurement is performed during fast kVp switching, then real-time current data is obtained, but measurement accuracy deteriorates due to system variations and rapid changes
Solution Approach 1:
The calibration factor is determined in advance during a calibration phase, storing the relationship between measured signal and actual tube current. This preliminary action eliminates the need for accurate real-time measurement during fast kVp switching, resolving the contradiction between response time and measurement accuracy.
Solution Approach 2:
The system uses the calibration factor to calculate tube current based on the measured signal during spectral imaging. This feedback mechanism allows accurate current determination without relying on direct real-time measurement, compensating for system variations and rapid changes during fast kVp switching.
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 accurate and timely regulation of X-ray tube current and focal spot control during fast kVp switching, improving image quality and patient safety by compensating for system variations and ensuring consistent spectral imaging.
Implementation Method 1
A filament current is applied to the filament, which current heats the filament
Implementation Method 2
heats the filament, causing the filament to expel electrons (thermionic emission)
Implementation Method 3
A peak tube voltage (kilovoltage peak kVp) is applied across the cathode and the anode and causes a beam of the electrons to accelerate from the cathode and impinge the anode. An interaction of the electrons with the material of the anode produces heat and radiation, including X-rays
Data Source
AI summary
The invention relates to a computer-implemented method of determining a tube current during X-ray kVp switching. The method includes generating (110) a calibration tube voltage pulse during a calibration phase, wherein the calibration tube voltage pulse comprises a first kVp plateau and a second kVp plateau different from the first kVp plateau; measuring (120), during the calibration tube voltage pulse, a first tube current at the first kVp plateau and a second tube current at the second kVp plateau; determining (130) a calibration factor from a ratio between the first tube current and the second tube current; measuring (140) a third tube current at a steady state of the first kVp plateau during a kVp switching phase; and determining (150) a fourth tube current at the second kVp plateau during the kVp switching phase, wherein the fourth tube current is determined based on the calibration factor and the third tube current at the first kVp plateau. The invention also relates to a high voltage generator (30) configured to carry out the computer implemented method, a computer program element and a computer readable medium, and an X-ray system.