Dose Adjustment Mechanism With Off-Axis Actuation for Radiation Therapy
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Solution Overview
Problem
Existing radiation therapy apparatuses face challenges in maintaining accurate dose distribution and preventing failures due to the proximity of radiation-sensitive components to the radiation axis, particularly in high-dose rate therapies without flattening filters.
Innovation Solution
A dose adjustment mechanism is implemented with an actuator positioned away from the radiation axis, using an interference element that moves perpendicular to the radiation axis to switch between states with and without a flattening filter, ensuring accurate positioning and reducing radiation exposure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If an actuator is disposed near the beam axis to enable compact integration, then device complexity is reduced, but reliability deteriorates due to radiation-induced failures
Solution Approach 1:
The actuator is extracted from the radiation axis region and disposed at a position apart from the radiation axis. This separation removes the radiation-sensitive actuator from the harmful radiation environment while preserving the functional integrity of the dose adjustment mechanism.
Solution Approach 2:
A radiation-resistant transmission mechanism serves as an intermediary between the actuator (disposed apart from the radiation axis) and the interference element. This intermediary transmits the actuation force or motion without requiring the actuator itself to be near the radiation axis, thus protecting the actuator from radiation while maintaining system functionality.
2Device complexity
If the operation shaft intersects the radiation axis to simplify mechanism design, then device complexity is reduced, but reliability worsens due to increased radiation exposure
Solution Approach 1:
The operation shaft is extracted from the radiation axis and repositioned so that it does not intersect the radiation axis. This geometric reconfiguration removes the direct intersection point, thereby reducing radiation exposure to the actuator and its critical components.
Solution Approach 2:
The operation shaft is repositioned in a different spatial dimension or orientation such that it runs parallel to or at an angle with the radiation axis rather than intersecting it. This dimensional change allows the mechanism to maintain its functional simplicity while avoiding the harmful radiation zone.
Data Source
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AI summary
A dose adjustment mechanism is to reduce an influence of radiation in the dose adjustment mechanism of a radiation therapy apparatus and to prevent occurrence of a failure. A dose adjustment mechanism 40 includes an actuator 42 disposed apart from a radiation axis irradiated with radiation by a radiation therapy apparatus 10, and a flattening filter 33 which is an interference element that moves in a direction perpendicular to the radiation axis by an operation of the actuator 42 and that is capable of switching between a state in which the interference element is disposed on an axis of the radiation axis and a state in which the interference element is not disposed on the axis of the radiation axis. An operation shaft of the actuator 42 does not intersect the radiation axis.