Thick Transmission X-ray Targets for Dose Reduction
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Solution Overview
Problem
Existing x-ray tubes produce unwanted low energy x-rays, which increase patient dose and reduce image quality in medical imaging, and there is a lack of reliable simulation tools for thick transmission targets, especially at high electron energies.
Innovation Solution
A transmission x-ray tube with thick target foils greater than 50 microns, made from materials like tantalum or molybdenum, attached to a substrate via diffusion bonding or hot pressing, which reduces low energy x-rays while enhancing higher energy characteristic line emissions, and uses a glass capillary to guide x-rays for improved imaging.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If thin transmission targets (8-41 microns) are used, then x-ray flux is maintained, but low energy x-rays are not sufficiently filtered increasing patient dose
Solution Approach 1:
The patent changes the critical parameter of target thickness from the conventional range (8-41 microns) to a thicker range (50-200 microns). This parameter change enables the target to simultaneously maintain sufficient x-ray flux output and effectively filter low energy x-rays, resolving the contradiction between patient dose reduction and flux maintenance.
Solution Approach 2:
The patent converts the previously harmful effect of target thickness (which was thought to always reduce flux) into a beneficial filtering mechanism. By using thicker targets, the natural absorption of low energy x-rays within the target material is harnessed to reduce patient dose, while the geometry and material selection ensure that useful higher energy x-rays are still transmitted effectively.
2Object-affected harmful factors
If target thickness is increased to filter low energy x-rays, then patient dose is reduced, but x-ray flux is degraded by absorption
Solution Approach 1:
The patent applies local quality by optimizing the target material composition and geometry at different regions. The target uses specific materials (tungsten, molybdenum, rhodium, iridium, platinum, gold) with appropriate atomic numbers and densities, and employs a curved or angled geometry that ensures uniform thickness in the path of useful x-rays while maintaining edge support, thereby preserving beam quality while achieving filtration.
Solution Approach 2:
The patent employs composite structures where a thick target material (providing filtration) is supported by a thin substrate or edge support structure (preserving flux). This composite approach allows the system to benefit from both the filtering properties of thick material and the flux-preserving properties of thin support structures.
3Object-affected harmful factors
If thick targets (>50 microns) are used, then low energy x-rays are filtered, but reliable simulation tools are unavailable for high electron energies
Solution Approach 1:
The patent makes the system self-optimizing by carefully selecting target materials and geometries that naturally produce desirable x-ray spectra. The thick target design with specific materials (tungsten, molybdenum, etc.) and geometries (curved, angled) is configured to inherently favor the production and transmission of characteristic higher energy x-rays while filtering low energy x-rays, reducing dependence on external simulation tools for optimization.
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
The solution significantly reduces low energy x-rays, minimizing patient dose while improving image quality and increasing the production of quasi-monochromatic x-rays for medical and industrial applications, and provides a more efficient heat management system.
Implementation Method 1
the thickness of at least one of the target foils is greater than about 50 microns... significantly reduces unwanted low energy x-rays... as transmission target thickness increases the thicker target absorbs x-rays produced when the electrons first enter the target
Implementation Method 2
electrons which are accelerated along an electron beam path and strike the anode target producing x-rays
Implementation Method 3
producing a spectrum of x-rays... enhancing higher energy characteristic line emissions from the target
Implementation Method 4
uses a glass capillary to guide x-rays for improved imaging
Data Source
AI summary
This invention relates to the use of thick target materials 50 microns and thicker for an x-ray transmission tube; to possible target material compositions including various elements and their alloys, eutectic alloys, compounds, or intermetallic compounds; and applications for utilizing such thick target transmission x-ray tubes. The target comprises at lease one portion of the target with a thickness of 50 microns or greater. The target can be optionally attached to a substrate end-window essentially transparent to x-rays or be thick enough so that no such substrate is required. Applications include producing a high percentage of monochromatic line mission x-rays of said thick target for use in reduced dose medical imaging and other non-destructive testing applications.