X-ray Tube Focus Size Control During Voltage Modulation
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Solution Overview
Problem
Existing X-ray computed tomography apparatuses face challenges in discretionary control of focus size during tube voltage modulation, as significant changes in tube voltage can deteriorate the proportional relationship between tube voltage and focus voltage, leading to unstable focus size maintenance.
Innovation Solution
The X-ray computed tomography apparatus includes a focus size control circuitry that applies a deflecting voltage to the deflector based on the tube voltage value and a predetermined size, using an X-ray tube characteristics value table to maintain a constant focus size during tube voltage modulation, allowing for discretionary control of the focus size.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If tube voltage modulation is performed to reduce exposure amount, then radiation dose is reduced, but focus size becomes unstable due to deteriorated proportional relationship between tube voltage and focus voltage
Solution Approach 1:
The patent implements feedback control by detecting the actual tube voltage value and using it to dynamically adjust the deflecting voltage applied to the deflector. The control circuitry continuously monitors tube voltage changes and modifies the deflecting voltage accordingly to maintain constant focus size, resolving the instability caused by tube voltage modulation.
Solution Approach 2:
The patent changes the parameter being controlled from focus voltage (which has proportional relationship with tube voltage) to deflecting voltage (which can be independently controlled). By applying deflecting voltage to the deflector based on detected tube voltage values, the system maintains focus size stability while allowing tube voltage modulation for dose reduction.
2Loss of energy
If tube voltage value significantly changes during modulation, then exposure amount is reduced, but discretionary control of focus size becomes difficult due to deteriorated proportional relationship
Solution Approach 1:
The control circuitry uses feedback from tube voltage detection to dynamically calculate and apply the appropriate deflecting voltage. This enables discretionary control of focus size because the system can adapt to any tube voltage value and maintain the desired focus characteristics through real-time adjustment of the deflecting voltage.
Solution Approach 2:
The patent replaces the mechanical/electrical proportional relationship system (where focus voltage automatically scales with tube voltage) with an electronically controlled deflection system. The deflector uses electronically adjustable voltage that can be independently controlled based on detected tube voltage, enabling precise discretionary control regardless of tube voltage modulation.
3Manufacturing precision
If focus size is maintained constant during tube voltage modulation, then image quality is improved, but control complexity increases due to need for dynamic voltage adjustment
Solution Approach 1:
The patent uses feedback control where the control circuitry detects tube voltage values and automatically adjusts deflecting voltage to maintain constant focus size. This automated feedback mechanism achieves precise focus size control without requiring complex manual intervention or sophisticated control algorithms.
Solution Approach 2:
The control circuitry performs self-adjustment by detecting tube voltage changes and automatically applying the appropriate deflecting voltage correction. The system serves itself by maintaining focus size stability through autonomous voltage adjustment based on real-time tube voltage detection, without external intervention.
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 solution enables stable and discretionary control of focus size even during tube voltage modulation, improving image quality by maintaining consistent focus measurements, as demonstrated in the graphs showing the effective focus size control during cyclic tube voltage variations.
Implementation Method 1
a deflector configured to deflect the electrons from the cathode
Implementation Method 2
an anode configured to generate X-rays upon receiving the electrons from the cathode
Data Source
AI summary
According to one embodiment, an X-ray computed tomography apparatus includes an X-ray tube, a high voltage power supply, and focus size control circuitry. The X-ray tube includes a cathode, an anode, and a deflector configured to deflect the electrons from the cathode. The high voltage power supply generates a tube voltage to be applied between the cathode and the anode. The focus size control circuitry controls a focus size formed in the anode by applying to the deflector a deflecting voltage of a deflecting voltage value based on a tube voltage value of the tube voltage and a predetermined size, in order to form a focus of the predetermined size in the anode during the period where the tube voltage is applied by the high voltage power supply.