RF Power Cable Routing for PET-MR Signal Integrity
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Solution Overview
Problem
In hybrid PET-MR systems, the mounting of RF power cables at the central section of the RF body coil leads to significant loss and attenuation of PET signals, affecting image quality, and existing workarounds to minimize shield currents require additional shielding or redesign of the magnet/gradient coil.
Innovation Solution
The RF power cables are routed along an outer surface of an RF shield and connected to an outer edge of an end ring of the RF body coil, minimizing transmit E-field induced currents on the shield without the need for additional shielding or magnet/gradient coil redesign.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If RF power cables are mounted at the central section of the RF body coil, then shield currents are minimized, but PET signal loss increases significantly
Solution Approach 1:
The patent transitions from mounting power cables at the central section (longitudinal position) to mounting them at the outer edge of the end ring (radial position). This dimensional change in cable placement moves the power delivery interface to a location where it does not interfere with the PET signal path through the coil center, thereby reducing signal loss while maintaining shield current minimization.
Solution Approach 2:
The patent introduces an intermediary structure (end ring with outer edge mounting location) that serves as a mediator between the power source and the RF coil elements. This intermediary mounting location allows power cables to be positioned away from the central signal path while still providing effective power delivery to the coil, resolving the conflict between power delivery and signal integrity.
2Object-generated harmful factors
If quarter wave sleeve and stub baluns are used to minimize shield currents, then shield currents are reduced, but device complexity increases due to additional shielding and redesign requirements
Solution Approach 1:
The patent extracts the problematic interaction between power cables and PET signals by separating the power cable mounting location from the central signal path. By taking out the cable mounting from the central section and relocating it to the end ring outer edge, the solution eliminates the need for additional shielding structures like quarter wave sleeves and stub baluns, thereby reducing device complexity while maintaining shield current minimization.
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 arrangement effectively minimizes PET signal loss and shield currents, maintaining image quality without requiring additional shielding or redesign of the magnet/gradient coil.
Implementation Method 1
the RF coil (i.e., whole body RF coil) that generates the RF magnetic field
Implementation Method 2
These RF power cables may be as thick as 8 mm in diameter or greater and carry ̃30-35 kW of RF power
Implementation Method 3
It is these gamma rays that are detected by the scintillators of the detector ring. When struck by a gamma ray, each scintillator illuminates
Implementation Method 4
activating a photovoltaic component, such as a photodiode
Implementation Method 5
magnetic field gradients (Gx, Gy, and Gz) are employed
Data Source
AI summary
A PET-MR apparatus includes an MR imaging system having an RF coil former having inner and outer surfaces, an RF shield formed about the outer surface of the RF coil former, and an RF coil positioned on the inner surface of the RF coil former. The PET-MR apparatus also includes a PET system having a detector array positioned to encircle the bore to acquire PET emissions of the subject of interest and a plurality of RF power cables to provide power to the RF coil. The RF coil of the PET-MR apparatus comprises an RF body coil including a pair of end rings and a plurality of rungs extending between the end rings, wherein the plurality of RF power cables are coupled to one of the pair of end rings, along an outer edge of the one end ring distal from the plurality of rungs.