MRI-Linac Coil Layout for Compact Magnetic Interference Shielding
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Solution Overview
Problem
Existing radiation therapy systems face challenges in integrating magnetic resonance imaging (MRI) and radiation therapy apparatuses in a compact structure without interference from high-intensity MRI magnetic fields, affecting therapeutic quality.
Innovation Solution
A therapeutic apparatus is designed with a magnetic resonance imaging (MRI) system that includes coaxially arranged main magnetic field coils and shielding coils, an annular cryostat, and a radiation therapy apparatus with a linear accelerator positioned within the annular recess, allowing for compact integration and reduced magnetic interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If passive shielding structures are provided surrounding the linear accelerator, then magnetic field interference is reduced, but the device complexity and space requirements increase
Solution Approach 1:
The patent replaces passive mechanical shielding structures with active magnetic field cancellation using shielding coils. Instead of using bulky passive shielding materials surrounding the linear accelerator, the invention employs coils that generate opposing magnetic fields to actively cancel the interference from main magnetic field coils, thereby reducing magnetic field interference without increasing structural complexity
Solution Approach 2:
The patent changes the approach from static passive shielding to dynamic active shielding by controlling the current parameters in shielding coils. By adjusting the current magnitude and direction in the shielding coils, the system can dynamically cancel magnetic field interference at different operational states, avoiding the need for fixed complex shielding structures
2Volume of moving object
If MRI apparatus and radiation therapy apparatus are integrated in a compact structure, then space efficiency is improved, but magnetic field interference between components increases
Solution Approach 1:
The patent implements a nested structure where the linear accelerator is positioned within the bore of the MRI apparatus, and shielding coils are nested between the main magnetic field coils and the linear accelerator. This nested arrangement allows compact integration of both apparatuses while the intermediate shielding coils protect the inner components from magnetic field interference
Solution Approach 2:
The patent introduces shielding coils as intermediary elements between the main magnetic field coils and the linear accelerator. These intermediary coils generate opposing magnetic fields that cancel the interference from the main coils, enabling close integration of the MRI and radiation therapy components without harmful magnetic interactions
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 solution enables high-therapeutic quality radiation therapy by minimizing magnetic interference while maintaining a compact structure, facilitating accurate tumor tracking and treatment planning using MRI data.
Implementation Method 1
a plurality of shielding coils including a first shielding coil, a second shielding coil and a shielding coil group arranged coaxially along the axis
Implementation Method 2
a linear accelerator configured to accelerate electrons in an electron beam to produce a photon beam of the therapeutic radiation
Data Source
AI summary
The present disclosure relates to a therapeutic apparatus including an MRI apparatus configured to acquire MRI data with respect to a region of interest. The MRI apparatus may include a plurality of main magnetic field coils coaxially arranged along an axis. The MRI apparatus may also include a plurality of shielding coils arranged coaxially along the axis. A current within at least one of the shielding coils may be in the same direction with a current within the main magnetic field coils.