X-Ray Tube Current Calibration for Fast kVp Switching
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Solution Overview
Problem
Existing methods struggle to accurately determine X-ray tube emission current during fast kVp switching in spectral CT imaging due to rapid changes and system variations, making timely and precise control of tube current and focal spot challenging.
Innovation Solution
A method involving a calibration phase to determine a calibration factor based on the ratio of tube currents at different kVp plateaus, allowing for accurate estimation of tube current during fast kVp switching, with closed-loop control and focal spot adjustments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If fast kVp switching is implemented for spectral imaging, then imaging speed and spectral information acquisition are improved, but tube current measurement accuracy deteriorates due to rapid changes and system variations
Solution Approach 1:
The system performs preliminary calibration by measuring tube current at both first and second kVp plateaus during a calibration phase before actual imaging. This preliminary action establishes a calibration factor that accounts for system variations, enabling accurate tube current determination during fast kVp switching without compromising imaging speed.
Solution Approach 2:
The calibration factor acts as an intermediary that bridges the relationship between tube current measurements at different kVp plateaus. By using this calibration factor, the system can accurately determine tube current at one plateau based on measurements at another plateau, resolving the measurement accuracy issue during fast switching.
2Productivity
If tube current is allowed to vary rapidly during kVp switching, then imaging efficiency is improved, but control precision of tube current and focal spot deteriorates
Solution Approach 1:
The system implements closed-loop control that continuously monitors tube current using the calibration factor and provides feedback to adjust tube current and focal spot settings. This feedback mechanism maintains control precision despite rapid kVp switching by dynamically compensating for system variations and filament cooling effects.
Solution Approach 2:
The system dynamically adjusts operating parameters including tube current, focal spot size, and kVp switching timing based on real-time conditions. By changing these parameters adaptively using the calibration factor, the system maintains imaging efficiency while preserving control precision throughout the spectral imaging process.
3Measurement precision
If calibration is performed frequently to maintain accuracy, then measurement precision is improved, but system downtime and productivity are reduced
Solution Approach 1:
The system performs comprehensive calibration during an initial calibration phase before clinical imaging, establishing a calibration factor that remains valid for an extended period. This preliminary calibration reduces the need for frequent recalibration, maintaining measurement precision while minimizing system downtime and preserving productivity.
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 size during fast kVp switching, improving image quality and patient safety by compensating for system variations and filament cooling effects.
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
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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.