X-ray Target Pedestal Assembly with Rotating Cooling and Protective Coating
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Solution Overview
Problem
The x-ray targets in radiation therapy systems degrade over time due to chemical corrosion from cooling fluids, leading to reduced photon conversion capacity and a limited target life, as the interaction of high-energy electrons with the target material generates thermal energy and produces free radicals that attack the target material.
Innovation Solution
A target pedestal assembly that includes a rotating x-ray target submerged in a cooling fluid with integrated flow diverters to guide coolant flow and a protective coating to reduce chemical reactivity, allowing for consistent rotation and efficient heat dissipation, thereby extending the target's life.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the target is cooled by submerging it in a cooling fluid, then heat transfer efficiency is improved, but chemical corrosion from the cooling fluid degrades the target material
Solution Approach 1:
A protective coating is applied to the target surface to act as an intermediary barrier between the cooling fluid and the target material. This coating allows heat to be transferred from the target to the cooling fluid while preventing direct chemical contact and corrosion of the target material by the cooling fluid and its decomposition products.
Solution Approach 2:
The target system becomes a composite structure consisting of the target material (such as tungsten or molybdenum) combined with a protective coating layer. This composite structure maintains the high thermal conductivity and heat resistance of the target material while adding the chemical protection properties of the coating material.
2Device complexity
If the target is stationary, then the structure is simple, but thermal energy accumulates and degrades the target
Solution Approach 1:
The target is designed to rotate on its axis rather than remain stationary. This dynamic motion allows the electron beam to strike different portions of the target surface sequentially, distributing the thermal energy input across a larger area and preventing localized overheating and degradation.
Solution Approach 2:
The rotation of the target creates a periodic action where different sections of the target surface are alternately exposed to the electron beam and the cooling fluid. This periodic exposure allows heat to be continuously dissipated while maintaining consistent photon conversion capacity.
3Temperature
If the target rotates to dissipate heat, then thermal management is improved, but the target may become misaligned or unstable
Solution Approach 1:
The target is designed to rotate on its axis rather than remain stationary. This dynamic motion allows the electron beam to strike different portions of the target surface sequentially, distributing the thermal energy input across a larger area and preventing localized overheating and degradation.
Solution Approach 2:
The rotation of the target creates a periodic action where different sections of the target surface are alternately exposed to the electron beam and the cooling fluid. This periodic exposure allows heat to be continuously dissipated while maintaining consistent photon conversion capacity.
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 enables the target to maintain high rotational speeds and efficient heat transfer, prolonging the target's life by preventing chemical corrosion and ensuring consistent photon conversion capacity.
Implementation Method 1
The target is bombarded with the electrons from the beam, and high-energy photons (x-rays) are produced as a result of the interaction between the fast moving electrons and the atomic structure of the target. The deceleration of electrons caused by the interaction of the electrons with the material of the target creates the x-rays in a process known as bremsstrahlung.
Implementation Method 2
The target may be cooled by any number of coolants, or cooling media, as keeping the target submerged in a coolant boosts the heat transfer away from the target.
Implementation Method 3
incident radiation causes oxidation, breaking down water molecules to produce free radical hydrogen and oxygen atoms that will attack and degrade the target material
Data Source
AI summary
An x-ray target pedestal assembly and a method of protecting the x-ray target from breaking down as a result of the extreme heat that is produced when an electron beam is aimed at the target to produce x-rays. The target is submerged in cooling fluid and is rotated by a constant flow of the cooling fluid over and around the target in order to dissipate heat. The fluid is guided by integrated flow diverters in the target cover. The target may also be protectively coated either in its entirety or along the electron beam path in order to further protect it from the heat of the electron beam impact or from breakdown as a result of attack of free radicals or other chemically reactive components of the cooling fluid which are produced in the extreme target environment.