Radiotherapy Magnetron Frequency Control for Dark Current Reduction
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Solution Overview
Problem
In radiotherapy, the occurrence of dark current during beam gating leads to undesired dose delivery to patients, deviating from the intended treatment plan and potentially causing damage to the beam generation system components.
Innovation Solution
A radiotherapy device with a controller that predicts resonant frequency changes in the accelerating structure and adjusts the magnetron's output frequency accordingly, minimizing dark current-related doses by maintaining optimal frequency matching during beam hold and release states.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the electron source is controlled to be off during beam gating, then the desired radiation dose delivery is improved, but dark current still causes undesired dose delivery and component damage
Solution Approach 1:
The system performs preliminary frequency adjustment of the magnetron based on predicted resonant frequency changes before beam release. This anticipatory action ensures the accelerating structure is already tuned to the correct frequency when the beam is released, preventing dark current issues during beam hold periods while maintaining precise dose delivery when the beam is active.
Solution Approach 2:
The system implements a feedback mechanism where the controller continuously monitors beam delivery state and adjusts the magnetron frequency accordingly. When the beam is held off, the controller predicts resonant frequency drift and adjusts the magnetron output frequency to compensate, thereby eliminating dark current while preserving the ability to deliver precise doses when the beam is on.
2Reliability
If the magnetron operates continuously to maintain frequency stability, then frequency matching is improved, but component deterioration and damage risk increase
Solution Approach 1:
Instead of continuous operation, the magnetron operates periodically - active during beam delivery and adjusted during beam hold periods. The controller applies periodic frequency adjustments based on predicted resonant frequency changes, maintaining stability only when needed for dose delivery while reducing overall operational stress and extending component lifespan.
Solution Approach 2:
The system dynamically changes the magnetron's operating parameters (output frequency) based on the beam delivery state. During beam hold, the frequency is adjusted to track predicted resonant frequency changes without continuous beam operation. During beam delivery, the frequency is optimized for dose delivery. This parameter adaptation maintains reliability while reducing unnecessary operational stress.
3Manufacturing precision
If beam gating is used to address subject motion, then dose delivery accuracy to target region is improved, but dark current causes dose deviation from treatment plan
Solution Approach 1:
The controller performs preliminary frequency adjustment of the magnetron based on predicted resonant frequency changes before beam release during gating cycles. This ensures that when the beam is released to deliver the gated dose, the accelerating structure is already optimally tuned, preventing dark current interference and maintaining fidelity to the treatment plan.
Solution Approach 2:
The system uses feedback from the beam delivery state to continuously adjust magnetron frequency. During gated beam delivery, the controller monitors when the beam should be on or off based on subject position, and simultaneously adjusts frequency to compensate for predicted resonant frequency drift. This dual control mechanism maintains both target accuracy and treatment plan fidelity by eliminating dark current dose deviations.
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 reduces dosimetric errors and extends the lifespan of the magnetron by ensuring accurate and reliable dose delivery, even during periods of beam inactivity, thereby improving the precision and reliability of the radiotherapy treatment.
Implementation Method 1
determine a predicted resonant frequency change of the accelerating structure based on a predicted operation of the radiotherapy device; and adjust an output frequency of the magnetron by the predicted resonant frequency change
Data Source
AI summary
A radiotherapy device, a computer-implemented method and a computer-readable medium are provided. The radiotherapy device comprises an accelerating structure, a magnetron and a controller communicatively coupled to the accelerating structure and the magnetron. The controller is configured to determine a predicted resonant frequency change of the accelerating structure based on an predicted operation of the radiotherapy device. The controller is further configured to adjust an output frequency of the magnetron by the predicted resonant frequency change.