X-Ray Tube Grid Voltage Control for Dual-Energy CT Transitions
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Solution Overview
Problem
Existing X-ray CT systems face challenges in achieving uniform X-ray dose and quality of projection data when switching between high and low tube voltages during dual energy scans, leading to potential damage from exceeding the upper limit tube current.
Innovation Solution
An X-ray tube control system that includes a tube voltage control unit and a grid control unit, which alternately switches tube and grid voltages to manage the transition periods and hold periods, ensuring the tube current does not exceed the upper limit, thereby maintaining dose uniformity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the tube voltage is alternately switched between high and low during dual energy scan, then the quality of projection data can be homogenized, but the tube current may exceed the upper limit during voltage transition periods
Solution Approach 1:
The grid voltage is switched in advance before the tube voltage transition to prepare the electron flow control. By preliminarily adjusting the grid voltage to appropriate levels before high-to-low or low-to-high tube voltage transitions, the system prevents tube current from exceeding upper limits during the transition period.
Solution Approach 2:
The grid electrode acts as an intermediary control element between the tube voltage switching and the tube current. By controlling the grid voltage independently, it mediates the electron flow to ensure safe tube current levels during tube voltage transitions, preventing harmful current overloads.
2Productivity
If the tube voltage transitions rapidly between high and low, then the scanning efficiency is improved, but the X-ray dose uniformity deteriorates
Solution Approach 1:
The system monitors the tube voltage transition periods and adjusts the grid voltage accordingly to maintain proper electron flow control. This feedback mechanism ensures that even during rapid voltage transitions, the X-ray dose remains uniform by dynamically adjusting the grid voltage to compensate for transition effects.
3Reliability
If the grid voltage is held during transition periods, then the tube current is controlled within safe limits, but the transition time is extended
Solution Approach 1:
The grid voltage control is dynamically adjusted based on the tube voltage transition state. Rather than static holding, the grid voltage is actively modulated during transition periods to maintain safe tube current limits while minimizing the duration of the transition, optimizing both safety and speed.
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 effectively maintains X-ray dose uniformity and prevents damage by controlling the tube current within safe limits during voltage transitions, enhancing the quality of projection data acquisition.
Implementation Method 1
a cathode that emits electrons
Implementation Method 2
an anode that generates X-rays upon reception of the electrons from the cathode
Data Source
AI summary
According to one embodiment, an X-ray tube control system includes a tube voltage control circuitry and a grid control circuitry. The grid control circuitry performs control to decrease a grid voltage to a first (ex. low) grid voltage and control to hold the first grid voltage exclusively within a first transition period in which a tube voltage makes a transition from a second (ex. high) tube voltage to a first tube voltage and a first (ex. low) hold period in which a tube voltage is held at the first tube voltage so as to prevent a tube current from exceeding an upper limit tube current based on allowable power.