X-ray Source Current Peaking for Dual Energy CT Voltage Transitions
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Solution Overview
Problem
In dual energy computed tomography (CT) imaging systems, the transition from high to low voltage in the x-ray source is slower due to a parasitic capacitor, leading to longer kV fall durations, which negatively impacts energy separation and image quality by reducing the accuracy of basis material decomposition and image reconstruction.
Innovation Solution
Controlling the x-ray source current to peak during the transition from high to low voltage, either by instantaneously increasing the current or gradually increasing the extract voltage, reduces the kV fall duration and improves energy separation and image quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the x-ray source voltage transitions from high to low, then the energy separation and image quality improve, but the transition duration becomes too long due to parasitic capacitor
Solution Approach 1:
The patent changes the current parameter during voltage transition by causing it to peak above the target current. This parameter modification accelerates the voltage transition from high to low by counteracting the parasitic capacitor's slowing effect, thereby reducing transition duration while maintaining energy separation accuracy.
2Productivity
If the voltage transition duration is reduced for faster switching, then productivity improves, but the parasitic capacitor causes slower transition
Solution Approach 1:
By dynamically adjusting the current parameter to peak above target during transition, the system overcomes the parasitic capacitor limitation and achieves faster voltage switching, improving productivity without being constrained by the natural RC time constant of the circuit.
3Duration of action of moving object
If the current is controlled to peak during voltage transition, then the transition duration is reduced, but additional control complexity is introduced
Solution Approach 1:
The system employs feedback control where the current is monitored and adjusted in real-time during voltage transition. The current is caused to peak above target based on feedback about the transition state, enabling automatic compensation for the parasitic capacitor effect without requiring complex manual intervention or additional hardware components.
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
This approach enables faster voltage switching, enhancing energy separation and image quality by shortening the kV fall duration, thus improving the accuracy of basis material decomposition and image reconstruction in dual energy CT imaging.
Implementation Method 1
In a given energy region of CT, two physical processes dominate the x-ray attenuation: Compton scattering and the photoelectric effect.
Implementation Method 2
In a given energy region of CT, two physical processes dominate the x-ray attenuation: Compton scattering and the photoelectric effect.
Data Source
AI summary
Methods and systems are provided for dual energy imaging. In one embodiment, a method comprises controlling an x-ray source with a first voltage to generate x-rays at a first energy, controlling the x-ray source with a second voltage to generate x-rays at a second energy lower than the first energy, and controlling a current of the x-ray source to peak above a target current when a voltage of the x-ray source is transitioning from the first voltage to the second voltage. In this way, the duration for transitioning from the first voltage to the second voltage is reduced, thereby enabling faster voltage switching of the x-ray source, improved energy separation in acquired projection data, and improved image quality.