Dynamically Adjustable Focal Spot for X-Ray Imaging
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Solution Overview
Problem
X-ray imaging systems face challenges in maintaining optimal focal spot size and shape over large fields of view, leading to distortion and reduced spatial resolution due to varying extraction angles, especially in pencil beam systems, where existing solutions are complex and inadequate.
Innovation Solution
The method involves dynamically adjusting the size, shape, and orientation of the electron beam cross-section and focal spot using focusing and stigmator coils to maintain a specified beam profile over a wide range of extraction angles, allowing real-time adjustments during image acquisition without moving parts inside the vacuum tube.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the electron beam is focused onto a small focal spot to improve spatial resolution, then the spatial resolution is improved, but the target overheats requiring cooling systems
Solution Approach 1:
The patent applies dynamics by making the focal spot size variable rather than fixed. The electron beam focusing system dynamically adjusts the focal spot dimensions based on the extraction angle, allowing the system to optimize between spatial resolution and heat distribution at different angles, thereby reducing peak temperatures on the target while maintaining imaging quality.
Solution Approach 2:
The patent changes the parameters of the electron beam (focal spot size, shape, and position) as a function of the extraction angle. By varying these parameters dynamically, the system prevents excessive heat concentration at any single location on the target, solving the overheating problem while preserving spatial resolution through angle-dependent optimization.
2Adaptability or versatility
If the x-ray extraction angle is increased to expand the field of view, then the field of view is enlarged, but the apparent focal spot size increases reducing spatial resolution
Solution Approach 1:
The patent makes the focal spot characteristics dynamic by adjusting them in real-time according to the extraction angle. As the extraction angle changes to expand the field of view, the focusing system simultaneously adjusts the focal spot size and shape to compensate for the apparent focal spot enlargement, thereby maintaining spatial resolution across the entire field of view.
Solution Approach 2:
The patent employs parameter changes by varying the electron beam focusing parameters (focal spot size, ellipticity, and orientation) as functions of the extraction angle. This dynamic parameter adjustment counteracts the geometric distortion that would otherwise cause apparent focal spot enlargement, preserving spatial resolution even at large extraction angles.
3Measurement precision
If the focal spot is fixed for optimal performance at one angle, then spatial resolution is optimized at that angle, but distortion occurs at other angles in the field of view
Solution Approach 1:
The patent transforms the fixed focal spot system into a dynamic one where the focal spot characteristics are continuously adjusted according to the extraction angle. This dynamic adaptation ensures that spatial resolution remains optimized across the entire angular range of the field of view, eliminating the distortion that would occur at off-center angles with a fixed focal spot.
Solution Approach 2:
The patent implements parameter changes by making the focal spot size, shape, and position dependent on the extraction angle. This angle-dependent parameter variation compensates for geometric distortions at different angles, maintaining consistent spatial resolution performance throughout the field of view rather than only at a single optimized angle.
4Adaptability or versatility
If conventional focusing methods are used with moving parts to adjust focal spot, then focal spot adjustment is possible, but the system complexity increases and reliability decreases
Solution Approach 1:
The patent replaces mechanical focusing adjustment mechanisms with an electromagnetic field-based system. By using electromagnetic lenses and focusing coils controlled by electronic signals, the system achieves focal spot adjustment without moving parts, thereby reducing mechanical complexity and improving reliability while maintaining full adjustability across the angular range.
Solution Approach 2:
The patent implements a self-adjusting system where the focal spot characteristics automatically adapt to the extraction angle through electronic control of the focusing fields. The system uses feedback from the beam deflection and extraction angle information to self-correct focal spot parameters, eliminating the need for complex mechanical adjustment mechanisms and reducing overall system complexity.
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 effectively corrects for extraction angle-dependent distortions, maintaining optimal focal spot characteristics across the entire angular scan range, enhancing spatial resolution and reducing the complexity of existing solutions.
Implementation Method 1
x-rays are generated when a beam of accelerated electrons impinges upon a target. The kinetic energy of the electrons is mostly converted to heat and only a small fraction to x-rays (referred to, in this context, as bremsstrahlung).
Implementation Method 2
The method involves dynamically adjusting the size, shape, and orientation of the electron beam cross-section and focal spot using focusing and stigmator coils
Data Source
AI summary
Methods for maintaining a specified beam profile of an x-ray beam extracted from an x-ray target over a large range of extraction angles relative to the target. A beam of electrons is generated and directed toward a target at an angle of incidence with respect to the target, with the beam of electrons forming a focal spot corresponding to the cross-section of the electron beam. At least one of a size, shape, and orientation of the electron beam cross-section is dynamically varied as the extraction angle is varied, and the extracted x-ray beam is collimated. Dynamically varying the size, shape or orientation of the electron beam cross-section may be performed using focusing and stigmator coils.