Field Emission X-ray Source Inverse Geometry
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Solution Overview
Problem
Conventional medical X-ray systems face challenges with image quality due to scattered radiation and inefficient detector technology, which also results in excessive exposure to patients and staff.
Innovation Solution
A medical X-ray imaging system with a flat, planar X-ray source using field emission guns and a digital flat-panel detector in inverse geometry, where the X-ray source surface is larger than the detector surface, significantly reducing scattered radiation and improving image quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If conventional vacuum tubes with thermal cathodes are used as X-ray sources, then X-ray radiation can be generated, but the system produces significant heat, has heavy weight, large dimensions, and low efficiency
Solution Approach 1:
The patent replaces the thermal cathode system (heating filament to emit electrons) with a field emission cathode system (applying electric field to emit electrons). This substitution eliminates the need for thermal heating, directly resolving the contradiction between efficiency and heat generation by using electric field emission instead of thermal emission
Solution Approach 2:
The patent changes the operating parameters of the cathode from thermal regime (high temperature operation) to field emission regime (low temperature with high electric field). This parameter change enables efficient electron emission without the energy loss associated with heating, thereby improving efficiency while reducing heat generation
2Measurement precision
If conventional X-ray emitters and flat-panel detectors are used, then X-ray imaging can be performed, but scattered radiation reduces image quality and increases radiation exposure
Solution Approach 1:
The patent inverts the conventional geometry by making the X-ray source larger than the detector surface. This inversion of the typical source-detector size relationship fundamentally changes the radiation geometry, reducing scattered radiation reaching the detector and thereby improving image quality while lowering radiation exposure
3Area of stationary object
If a large X-ray detector is used to capture the entire source surface, then complete imaging is achieved, but the system becomes less efficient and image quality decreases
Solution Approach 1:
Instead of making the detector as large as the source (conventional approach), the patent inverts this relationship by making the source larger than the detector. This allows the use of a smaller, more efficient detector while maintaining complete imaging capability through the inverse geometry arrangement
Solution Approach 2:
The patent applies local quality by concentrating the detected X-ray flux more intensely on the smaller detector surface through the inverse geometry arrangement. This creates a more favorable signal-to-noise ratio and improves detection efficiency, thereby enhancing image quality
4Duration of action of stationary object
If thermal cathodes are used in X-ray sources, then electron emission is achieved, but the lifespan is limited and startup time is increased due to heating requirements
Solution Approach 1:
The patent replaces the thermal cathode system with a field emission cathode system, eliminating the heating process entirely. This substitution directly extends lifespan by avoiding thermal degradation and reduces startup time by enabling immediate electron emission upon application of the electric field
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 configuration enhances image quality, reduces radiation exposure, and provides a compact, efficient, and cost-effective solution with lower heat generation and longer lifespan of the X-ray source, enabling high spatial resolution and rapid movement capabilities.
Implementation Method 1
In a field emission cathode, electrons are emitted as a result of a sufficiently high electric field being applied
Implementation Method 2
an electron beam is emitted from a metal filament cathode heated to over 1000° C. in an evacuated glass tube and accelerated toward a metal anode made, for example, of tungsten, as a result of which X-radiation is generated
Data Source
AI summary
In order to achieve improved image quality in X-ray photographs, a medical X-ray imaging system, comprising a flat, planar X-ray source having a surface with X-ray focal points arranged adjacent to one another and an X-ray detector with a sensor surface, is provided. The X-ray source has a plurality of field emission guns with at least one field emission cathode and the surface with focal points of the X-ray source is larger in size than the sensor surface of the X-ray detector.