Toroidal Superconducting Magnets for Hadron Therapy Gantry Weight Reduction
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Solution Overview
Problem
Existing gantry designs for proton and carbon beam therapy are heavy due to the need for external ferromagnetic shielding or additional coils to mitigate stray magnetic fields, and they lack the ability to efficiently vary beam energy for depth scanning in hadron therapies.
Innovation Solution
The use of toroidal superconducting magnets as lightweight rotating bending magnets, which are self-shielded and do not require ferromagnetic material for field modification, allowing for the creation of achromatic magnets by combining two toroidal magnets to achieve consistent beam deflection across varying energies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If dipole-type bending magnets are used in gantry designs, then beam bending function is achieved, but the weight of the magnet system increases due to required ferromagnetic shielding or additional coils
Solution Approach 1:
The patent applies the toroidal magnet configuration which inherently produces a self-cancelling stray magnetic field pattern. The field lines form closed loops within the toroidal structure, causing the harmful stray fields to cancel each other out naturally without requiring additional shielding materials or compensating coils, thus converting the potential harm into a beneficial self-shielding property
Solution Approach 2:
The magnet system is segmented into multiple toroidal bending magnets arranged in sequence, where each magnet operates independently with its own self-shielding configuration. This segmentation allows the system to achieve the required total bending angle while maintaining the weight advantages of individual toroidal magnets without requiring a single large dipole magnet with extensive shielding
2Ease of operation
If a large aperture is provided in the final bending magnet for beam scanning, then beam interception is prevented, but the size and weight of the magnet increases
Solution Approach 1:
The patent utilizes the three-dimensional toroidal geometry to provide aperture in multiple spatial dimensions simultaneously. The toroidal structure with its major and minor radii creates opening space in radial, axial, and azimuthal directions, allowing the scanning beam to pass through without interception while maintaining a compact overall magnet footprint and weight
3Adaptability or versatility
If beam energy is varied for depth scanning in hadron therapies, then treatment depth control is achieved, but the magnetic field must be adjusted to compensate for energy variation
Solution Approach 1:
The patent employs multiple toroidal bending magnets that are identical or similar in configuration, arranged in sequence along the beam path. This copying approach allows the system to handle variable beam energies more effectively, as each magnet can be designed with optimal parameters and the collective system provides the necessary bending while accommodating energy variations without requiring complex individual field adjustments
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 solution reduces the weight and size of the magnet system, enables efficient beam scanning in three dimensions, and allows for higher magnetic fields, making it suitable for both proton and carbon therapies by minimizing stray fields and eliminating the need for additional shielding.
Implementation Method 1
a beam of charged particles directed toward one of the plurality of gaps in the toroidal magnet, wherein a path of the beam is planar with the major axis and the path forms an angle with the major axis which is greater than 0°
Implementation Method 2
The toroidal magnet has the advantage that there is no need, or minimal need, for magnetic shielding. Thus, the iron required in the case of simple dipoles, or the second coil needed to cancel the far fields, is not needed, substantially decreasing the weight of the system.
Data Source
AI summary
Toroidal superconducting magnets can be used as lightweight rotating bending magnets in hadron therapy gantries. The toroidal bending magnets are self-shielded and do not require ferromagnetic material for field modification or shielding, decreasing both the magnet system weight, as well as overall gantry weight. Achromatic magnet can be made by combining two of these bending magnets. The simple geometry may allow the use of higher fields, making it attractive for carbon, as well as proton.