Magnetic Shims for Coil Positioning in Particle Therapy

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

In particle therapy systems, the precise positioning of superconducting coils is critical to prevent physical damage and ensure accurate particle beam extraction, but mechanical movements during rotation can disrupt the coil's position, affecting the magnetic field and particle beam energy.

Innovation Solution

The use of movable magnetic shims made of ferromagnetic material, positioned within slots in the magnetic structures adjacent to the cryostat, allows for adjustment of the coil's position by modifying the magnetic field, compensating for movements caused by rotation and maintaining precise alignment.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If mechanical structures are used to hold the coil, then the coil position can be maintained, but mechanical movements during rotation disrupt the coil position

Engineering Contradiction:

Improvecoil position stabilityVSAvoidrotation capability

Core Design Contradiction:

ReliabilityVSAdaptability or versatility

Solution Approach 1:

The patent replaces mechanical positioning structures with a magnetic field-based positioning system. Magnetic shims made of ferromagnetic material are positioned within slots in the yoke structure to generate magnetic forces that hold the superconducting coil in precise position. This magnetic positioning system allows the coil to maintain stable position during gantry rotation without mechanical constraints, resolving the contradiction between position stability and rotation capability.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Manufacturing precision

If the coil position is fixed precisely, then particle beam extraction is accurate, but mechanical forces from rotation affect the coil position

Engineering Contradiction:

Improvecoil positioning precisionVSAvoidmagnetic forces on coil

Core Design Contradiction:

Manufacturing precisionVSForce

Solution Approach 1:

The patent replaces mechanical force-based positioning with magnetic field-based positioning. The magnetic shims create controlled magnetic forces that precisely position the coil without mechanical contact. This eliminates the harmful mechanical forces from rotation while maintaining precise coil positioning, allowing accurate particle beam extraction.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent uses adjustable magnetic shims that can be positioned at different locations and orientations within the yoke slots to fine-tune the magnetic field distribution. By changing the magnetic field parameters through shim adjustment, the system achieves precise coil positioning while compensating for forces during rotation.

Inventive Principle:

Principle #35Parameter changes

3Manufacturing precision

If magnetic shims are added to adjust coil position, then coil positioning accuracy improves, but device complexity increases

Engineering Contradiction:

Improvecoil positioning accuracyVSAvoidmagnetic shim structure

Core Design Contradiction:

Manufacturing precisionVSDevice complexity

Solution Approach 1:

The patent replaces complex mechanical positioning mechanisms with relatively simple magnetic shims that can be inserted into pre-formed slots in the yoke structure. The magnetic shims are made of ferromagnetic material and can be positioned at various locations to achieve the desired coil positioning. This magnetic approach is simpler than mechanical adjustment mechanisms while providing comparable or superior positioning accuracy.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

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 ensures stable operation of the particle accelerator by maintaining the coil's position and adjusting the magnetic field to match the required energy for particle beam extraction, preventing physical damage and ensuring accurate beam delivery.

Implementation Method 1

one or more magnetic shims in one or more corresponding slots. The one or more magnetic shims are movable to adjust a position of the coil by changing a magnetic field produced by the magnetic structures

Methodology Applied

Scientific EffectMagnetic field: Magnetic Field

Implementation Method 2

The one or more magnetic shims may include ferromagnetic material

Methodology Applied

Scientific EffectFerromagnetism: Ferromagnetism

Data Source

PatentEP2901824B1Magnetic shims to adjust a position of a main coil and corresponding method

Publication Date: 2020.04.15 MEVION MEDICAL SYSTEMS INC

Figure 1
Figure 2
Figure 3

AI summary

An example particle accelerator includes a coil to provide a magnetic field to a cavity; a cryostat comprising a chamber for holding the coil, where the coil is arranged in the chamber to define an interior region of the coil and an exterior region of the coil; magnetic structures adjacent to the cryostat, where the magnetic structures have one or more slots at least part-way therethrough; and one or more magnetic shims in one or more corresponding slots. The one or more magnetic shims are movable to adjust a position of the coil by changing a magnetic field produced by the magnetic structures.