MRI Receive Coil Segmentation for Uniform Beam Attenuation
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Solution Overview
Problem
Current MRI receive coils are not optimal for use in combined MRI-radiotherapy systems, as they can cause detuning and non-uniformities in the radiation beam due to overlaps and vias, leading to interference with the treatment beam.
Innovation Solution
A radiofrequency receive coil assembly with two conductive loops, made of conductive material, lying in the same plane and electrically connected at a node, with a substrate and insulating regions to ensure uniform attenuation of ionizing radiation and minimize mutual inductance, allowing for decoupling of components and uniform beam passage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If overlapping conductive loops are used in the receive coil assembly, then the coil coverage area is increased, but non-uniform attenuation of the treatment beam occurs
Solution Approach 1:
The receive coil assembly is segmented into multiple non-overlapping conductive loops arranged in a specific pattern. Each loop is electrically isolated from others, preventing the formation of overlapping regions that would cause non-uniform beam attenuation. This segmentation allows the coil to maintain broad coverage while ensuring uniform treatment beam passage through the treatment beam region.
2Reliability
If vias are used to electrically connect conductive loops, then the coil circuitry is completed, but detuning of the coil occurs
Solution Approach 1:
The problematic vias that cause detuning are extracted and removed from the treatment beam region. Instead, electrical connections between conductive loops are established through alternative means such as edge-coupling or indirect connections positioned outside the treatment beam path. This extraction eliminates the detuning effect while preserving the essential coil circuitry functionality.
3Ease of operation
If a single-layer conductive structure is used, then the treatment beam passes through uniformly, but the coil Q-factor may be degraded
Solution Approach 1:
The coil assembly employs local quality variations where different regions serve different functions. The treatment beam region contains only single-layer non-overlapping conductive structures to ensure uniform beam passage, while other regions may contain multi-layer structures or additional circuitry elements to maintain optimal Q-factor. This spatial differentiation of structural complexity allows both requirements to be satisfied simultaneously.
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 provides uniform attenuation of the treatment beam, reducing interference with the radiation therapy while maintaining the performance of the MRI system, ensuring consistent imaging and treatment without degrading the Q-factor of the coil circuitry.
Implementation Method 1
A receive coil (which is also sometimes referred to as a receiver coil or a radiofrequency coil) converts electromagnetic radiation to an electrical current
Implementation Method 2
The static magnetic field tends to align the proton spins (e.g. their magnetic dipoles) in the direction of the field where they precess around the field's axis
Implementation Method 3
Energy from an oscillating magnetic field is temporarily applied to the patient at an appropriate resonant frequency to excite the protons, thereby causing a flip of their spin states
Implementation Method 4
The excited hydrogen atoms emit a radio frequency signal, which is measured by a receive coil
Data Source
AI summary
A radiofrequency receive coil assembly can include a first conductive loop and a second conductive loop electrically connected at a node. The first and second conductive loops can extend into a treatment beam region of the radio frequency receive coil assembly through which one or more beams of ionizing radiation pass. The first conductive loop and the second conductive loop can overlap each other to provide electromagnetic isolation and/or can use a common conductor combined with a shared capacitor to provide electromagnetic isolation, with the shared capacitor or other electrical components, as well as any conductive loop overlaps, being positioned outside of the treatment beam region. These features can, among other possible advantages, minimize and homogenize attenuation of the beams of ionizing radiation by the radiofrequency receive coil assembly.