X-ray Tube Cathode Focus Control for Anode Wear Reduction
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Solution Overview
Problem
The existing X-ray computed tomography imaging apparatus faces challenges in maintaining the cleanliness and longevity of the X-ray tube, as the warm-up process using a cathode can shorten the cathode's life and cause surface roughening of the anode due to fixed focus size and position during both scan and warm-up operations.
Innovation Solution
The apparatus selectively switches the focus size and position of thermoelectrons between scan and warm-up using a regulator, employing different focus sizes and positions for warm-up and scan to minimize wear and efficiently heat the anode, thereby extending the cathode's life and preventing surface roughening.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the X-ray tube is warmed up by applying high voltage and supplying filament heating current using the cathode, then the cleanliness in the X-ray tube is maintained and the anode temperature is raised to a predetermined value, but the life of the cathode is shortened
Solution Approach 1:
The patent divides the cathode into multiple filaments (first filament and second filament), allowing separate warm-up and scan operations to use different filaments. This segmentation enables the warm-up function to be performed by one filament while preserving another filament for scan operations, thereby extending the overall cathode life while maintaining the required anode temperature.
Solution Approach 2:
Different filaments are designed with different local characteristics (different emission areas and focal spot sizes). The first filament has a larger emission area suitable for warm-up, while the second filament has a smaller emission area optimized for scan operations. This local quality differentiation allows each filament to be optimized for its specific function.
2Device complexity
If the focus size is fixed during warm-up and scan operations, then the X-ray tube structure is simple, but the anode surface roughens due to concentrated electron bombardment
Solution Approach 1:
The patent employs different focal spot sizes for different operations: a larger focal spot for warm-up and a smaller focal spot for scan. By matching the focal spot size to the operational requirements, the electron bombardment is distributed over a larger area during warm-up, preventing excessive localized heating and surface roughening, while maintaining the necessary image quality during scan operations.
Solution Approach 2:
The system dynamically switches between different focal spot configurations based on the operational mode (warm-up or scan). The focus size is adjusted according to the specific operation being performed, allowing the system to optimize both anode surface quality and imaging performance without requiring a permanently complex focus control mechanism.
3Device complexity
If the same cathode filament is used for both warm-up and scan operations, then the device structure is simple, but the cathode life is reduced due to continuous usage
Solution Approach 1:
The cathode is segmented into multiple independent filaments, each capable of performing both warm-up and scan functions. This allows the system to distribute the operational load across multiple filaments, effectively extending the operational life of the cathode assembly while maintaining structural simplicity and functional flexibility.
Solution Approach 2:
Each filament in the multi-filament cathode is designed to be multi-functional, capable of performing both warm-up and scan operations. This universality provides redundancy and extends system life, as any single filament can potentially replace another if it fails, while maintaining all required functions.
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 allows for efficient warm-up of the X-ray tube while reducing focus roughness and extending the life of the cathode, enabling continuous X-ray generation during scans without discharge.
Implementation Method 1
a cathode configured to generate thermoelectrons
Implementation Method 2
a regulator configured to apply an electric field or a magnetic field to focus or bias the thermoelectrons from the cathode
Implementation Method 3
a regulator configured to apply an electric field or a magnetic field to focus or bias the thermoelectrons from the cathode
Implementation Method 4
an anode configured to generate X-rays upon receiving the thermoelectrons from the cathode
Data Source
AI summary
According to one embodiment, an X-ray computed tomography imaging apparatus includes an X-ray tube, an X-ray detector, and control circuitry. The X-ray tube includes a cathode configured to generate thermoelectrons, an anode configured to generate X-rays upon receiving the thermoelectrons from the cathode, and a regulator configured to apply an electric field or a magnetic field to focus or bias the thermoelectrons from the cathode. The X-ray detector detects the X-rays generated by the anode. The control circuitry controls the regulator to switch at least one of the size and position of the focus of the thermoelectrons from the cathode on the anode between scan and warm-up.