X-Ray Focus Regulation Using Combined Position and Deflection Feedback
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Solution Overview
Problem
The existing methods for regulating the position of a jump focus in X-ray imaging systems, particularly in CT systems, face limitations in dynamics and susceptibility to interference due to cascaded control loops and processing delays, leading to reduced image resolution and increased motion blur.
Innovation Solution
A single-loop regulation method using a common control unit and system for the X-ray focus, combining measured and model-based positions to determine a manipulated variable for correcting the focus position, which reduces idle time and enhances control dynamics, thereby improving image quality and reproducibility of jump transitions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a cascaded control loop with separate position detection and deflection control is used, then the position of the X-ray focus can be regulated, but the control dynamics are reduced and susceptibility to interference increases due to processing delays
Solution Approach 1:
The patent combines the position detection unit and deflection control unit into a single integrated control unit that performs both functions simultaneously. This merging eliminates the cascaded control loop structure and its associated processing delays, allowing the system to detect position and control deflection in a unified manner, thereby improving control dynamics while maintaining regulation accuracy
Solution Approach 2:
The integrated control unit calculates the required deflection current in advance based on the measured position and desired target position, before the position change is fully executed. This preliminary calculation allows the system to anticipate and compensate for position deviations more rapidly, improving control response time and reducing susceptibility to interference
2Measurement precision
If the recording time is reduced to improve imaging resolution, then the motion blur decreases, but the time required to change the jump position must also be reduced to avoid increasing motion blur
Solution Approach 1:
The patent implements dynamic control of the electron beam deflection that adapts to the recording time requirements. The integrated control unit continuously adjusts the deflection current based on real-time position feedback, enabling the system to achieve rapid jump position transitions that are synchronized with the reduced recording time, thereby maintaining imaging resolution without increasing motion blur
3Manufacturing precision
If mechanical tolerances and deflection effects are reduced to improve focus position accuracy, then motion blur decreases, but the complexity of the control system increases
Solution Approach 1:
The patent employs a feedback mechanism where the position detection unit continuously measures the actual position of the X-ray focus and feeds this information back to the integrated control unit. The control unit then adjusts the deflection current to correct any deviations from the target position, compensating for mechanical tolerances and deflection effects without requiring complex mechanical precision
Solution Approach 2:
The patent replaces reliance on mechanical precision with an electromagnetic control system. Instead of requiring mechanically perfect alignment and stable anode rotation, the system uses electromagnetic deflection of the electron beam to achieve precise focal spot positioning, thereby reducing the impact of mechanical tolerances while keeping the control system manageable through integration
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 results in more dynamic control of the X-ray focus, reducing susceptibility to interference and motion blur, leading to improved image quality and faster transition times between focus positions.
Implementation Method 1
Electrons are emitted from a cathode in the X-ray source and are accelerated to an anode, also referred as anode plate. On the anode plate, the electrons are focused on a so-called focal spot, also called X-ray focus, and they cause the emission of an X-ray beam.
Implementation Method 2
The position of the X-ray focus is changed dynamically by deflecting an electron beam in the X-ray source using an electromagnetic deflection unit.
Data Source
AI summary
In a method for regulating a position of an X-ray focus on the anode of an X-ray source of a scan unit of an X-ray imaging system, a combined actual position of the X-ray focus is determined by a combination of a measured position of the X-ray focus and a model-based position of the X-ray focus, which is determined based on a measured value of a deflection current. On the basis of the combined actual position and a target position, a manipulated variable is determined. On the basis of the determined manipulated variable, a regulation is performed to correct a deviation of the position of the X-ray focus from the target position.