Linear Accelerator Orientation in MRI Bore for Dose Precision
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Solution Overview
Problem
Current integration of linear accelerators with MRI devices faces challenges such as electron deflection due to magnetic fields, RF interference, and perturbed dose distribution, which limit the effectiveness and practicality of image-guided radiation therapy.
Innovation Solution
A radiation therapy system where the linear accelerator is positioned to be immersed in and oriented parallel to the MRI magnetic field, minimizing electron deflection and RF interference, and allowing for a higher magnetic field strength without perturbing the dose distribution, enabling sharper dose delivery and compact system design.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the linear accelerator is positioned close to the MRI apparatus, then the system becomes more compact, but electron deflection due to magnetic field increases
Solution Approach 1:
The linear accelerator is positioned asymmetrically within the MRI bore, specifically offset from the central axis along the bore direction. This asymmetric positioning allows the electron beam to travel parallel to the main magnetic field lines, minimizing the Lorentz force effect and electron deflection while maintaining a compact overall system configuration.
Solution Approach 2:
The solution transitions from conventional perpendicular positioning (where the electron beam path is perpendicular to the magnetic field) to a parallel configuration along the bore axis. This dimensional reorientation of the electron beam trajectory relative to the magnetic field lines eliminates the harmful deflection effect while preserving compactness.
2Device complexity
If the linear accelerator is positioned perpendicular to the MRI magnetic field, then electron acceleration is simpler, but dose distribution is perturbed
Solution Approach 1:
Instead of positioning the linear accelerator perpendicular to the MRI magnetic field (conventional approach), the invention inverts this arrangement by positioning the electron beam path parallel to the magnetic field lines. This inversion eliminates the harmful perturbation of dose distribution caused by Lorentz force deflection while maintaining relatively simple acceleration system design.
3Measurement precision
If higher MRI field strength is used, then image quality improves, but electron deflection and RF interference increase
Solution Approach 1:
The invention converts the potentially harmful strong magnetic field into a beneficial configuration by aligning the electron beam parallel to the field lines. This allows the strong MRI field to provide excellent image quality while the parallel geometry prevents Lorentz force deflection. The reduced electron deflection also minimizes RF interference, effectively converting what would be harmful high field strength into a beneficial imaging capability.
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 configuration reduces electron deflection, minimizes RF interference, allows for higher MRI field strengths, and results in a more compact and efficient radiation therapy system with improved dose distribution and beam sharpness, suitable for standard-sized treatment suites.
Implementation Method 1
An MRI functions by providing a homogeneous, and strong magnetic field that aligns the nuclear magnetic moments of target nuclei; hydrogen nuclei (protons) are the most common imaging target in MRI
Implementation Method 2
expose the linear accelerator to magnetic force that directs electrons therein along a central axis thereof
Data Source
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AI summary
A radiation therapy System comprises a magnetic resonance imaging (MRI) apparatus and a linear accelerator capable of generating a beam of radiation. The linear accelerator is immersed in and oriented with respect to the MRI magnetic field to expose the linear accelerator to magnetic force that directs particles therein along a central axis thereof.