Direct-Drive Gantry Rotation for Precise Radiation Source Positioning
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Solution Overview
Problem
Conventional drive systems for radiation therapy systems, such as gear-driven, belt-driven, and cable-driven systems, face issues with gear backlash, slip, wear, and susceptibility to foreign objects, making them unsuitable for high precision and repeatable rotational positioning of radiation sources.
Innovation Solution
A direct-drive electrical motor system with a first assembly fixed to the base stand and a second assembly fixed to the rotatable gantry, utilizing magnetic flux across an air gap to rotate the gantry without a mechanical drivetrain, enabling precise and repeatable rotational positioning.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional mechanical drivetrain systems (gear-driven, belt-driven, cable-driven) are used to rotate the gantry, then the system can provide sufficient torque for gantry rotation, but the system suffers from gear backlash, slip, wear, and susceptibility to foreign objects, reducing positioning precision and reliability
Solution Approach 1:
The patent replaces the conventional mechanical drivetrain system (gears, belts, cables) with an electromagnetic direct-drive system. The electromagnetic motor generates rotational force directly through magnetic fields acting on a rotor, eliminating mechanical transmission components. This substitution resolves the technical contradiction by providing both high reliability/precision positioning and reduced device complexity, as the direct-drive electromagnetic system eliminates gear backlash, slip, and wear associated with mechanical drivetrains.
Solution Approach 2:
The patent extracts and removes the intermediate mechanical drivetrain components from the gantry rotation system. By taking out the gears, belts, and cables that constitute the mechanical transmission system, the invention achieves direct coupling between the electromagnetic motor and the gantry. This extraction eliminates the sources of backlash, slip, and wear, thereby improving positioning precision while simplifying the overall system structure.
2Reliability
If a mechanical drivetrain is used between the motor and gantry, then the system can transmit rotational motion, but the intermediate mechanical components increase the risk of damage from foreign objects and reduce repeatable positioning accuracy
Solution Approach 1:
The patent replaces the mechanical drivetrain with a direct-drive electromagnetic motor system where the rotor is directly coupled to the gantry. This substitution eliminates mechanical transmission components that are vulnerable to foreign object damage and sources of positioning error. The electromagnetic coupling provides protected internal magnetic fields that are not susceptible to external contaminants, thereby improving both reliability and protection against harmful factors.
Solution Approach 2:
The direct-drive electromagnetic design inherently cushions against foreign object impacts by eliminating exposed mechanical transmission components. The sealed electromagnetic motor structure protects internal components from contaminants, and the direct coupling removes intermediate elements that could be damaged or cause positioning errors when exposed to foreign objects in the treatment environment.
3Measurement precision
If a direct-drive electrical motor is used without a mechanical drivetrain, then the system achieves high precision and repeatable rotational positioning, but the motor must generate sufficient torque directly, requiring a larger motor size
Solution Approach 1:
The patent employs parameter changes in the electromagnetic motor design, specifically utilizing high-energy permanent magnets and optimized magnetic circuit configurations. By changing the magnetic field strength parameters and motor construction details, the system achieves high torque output from a compact motor volume. This allows the direct-drive motor to provide sufficient gantry rotation torque while maintaining a space-efficient design that does not excessively increase motor size.
Solution Approach 2:
The patent utilizes composite material structures in the motor construction, including high-performance permanent magnets and optimized magnetic materials. These composite material solutions enable the motor to generate high torque density, providing the necessary rotational force for gantry movement while keeping the motor volume compact. The advanced materials allow efficient energy conversion and high force output from a reduced size.
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 direct-drive system provides high torque with minimal mechanical interference, ensuring accurate and repeatable rotational positioning of the radiation source, reducing the risk of damage and improving positional accuracy in radiation therapy.
Implementation Method 1
magnetic flux across the air gap causes the electric motor to rotate the rotatable gantry
Data Source
AI summary
A radiation treatment system includes a base stand fixed to or resting on a support surface external to the radiation treatment system, a rotatable gantry with a treatment-delivering radiation source mounted thereon, wherein the rotatable gantry is rotatably coupled to the base stand via a bearing, and an electric motor for rotating the rotatable gantry and a portion of the bearing fixed to the gantry. The electric motor includes a first assembly that is fixed to the base stand; and a second assembly that is fixed to the gantry and is separated from the first assembly by an air gap, wherein magnetic flux across the air gap causes the electric motor to rotate the rotatable gantry and the portion of the bearing fixed to the rotatable gantry.