Hybrid PET/MR Scanner RF Isolation and Magnetic Field Compensation
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Solution Overview
Problem
The integration of magnetic resonance (MR) scanners with other imaging modalities, such as PET or SPECT, is challenging due to radio frequency interference and magnetic field distortions, making it difficult to create a hybrid imaging system that is efficient and compatible with existing MR scanners.
Innovation Solution
A hybrid imaging system is designed where the second modality imaging system, such as PET, is placed within the same radio frequency isolation space as the MR scanner, with shim coils and magnetic shielding to compensate for magnetic field distortions and reduce interference, allowing for efficient co-location and retrofitting of systems.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the PET scanner is placed outside the radio frequency isolation space, then radio frequency interference is reduced, but spatial registration errors increase due to long patient transfer distance
Solution Approach 1:
A movable partition wall with an opening is introduced as an intermediary structure between the PET scanner room and the MR scanner room. This partition wall allows the patient table to pass through while maintaining RF isolation when closed, and enabling patient transfer when opened, thus mediating between the conflicting requirements of RF shielding and patient accessibility.
Solution Approach 2:
The partition wall is designed to be movable rather than fixed, allowing it to dynamically switch between open and closed states. When closed, it provides RF isolation; when open, it facilitates patient transfer. This dynamic characteristic resolves the contradiction by adapting the system's configuration based on operational requirements.
2Measurement precision
If the PET scanner is integrated into the MR scanner gantry, then spatial registration is improved, but radio frequency interference from PET electronics increases
Solution Approach 1:
The hybrid imaging system is segmented into separate physical locations: the PET scanner is placed in a separate room adjacent to the MR scanner room, rather than integrating PET electronics into the MR gantry. This segmentation maintains spatial registration capability through coordinated patient table positioning while isolating RF-sensitive MR components from RF-interfering PET electronics.
Solution Approach 2:
The movable partition wall serves as an intermediary that enables close proximity of PET and MR scanners while maintaining RF isolation. It allows the patient table to be continuously positioned for both modalities without requiring physical integration of the scanner systems, thus preventing RF interference while maintaining spatial coordination.
3Object-affected harmful factors
If the PET scanner is placed in a separate room, then radio frequency interference is reduced, but workflow efficiency decreases due to patient transfer requirements
Solution Approach 1:
The movable partition wall dynamically adapts to workflow needs by being open during patient transfer and closed during imaging procedures. This dynamic configuration minimizes the impact on workflow efficiency while maintaining RF isolation during critical imaging operations, resolving the contradiction between separation benefits and workflow continuity.
Solution Approach 2:
The partition wall with its opening acts as a mediator that enables efficient patient transfer between rooms without requiring complex transfer mechanisms like railways. The opening allows direct access while the wall structure maintains RF isolation, thus improving workflow efficiency compared to long-distance transfer systems while preserving RF protection.
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 enables efficient and effective integration of MR and PET imaging in a single room without degrading either modality, allowing for seamless workflow and minimal patient disturbance, while enabling efficient retrofitting of existing MR systems.
Implementation Method 1
a magnetic resonance scanner located in a specially designed radio frequency isolation space created by a surrounding Faraday cage-type radio frequency shield
Implementation Method 2
shim coils and magnetic shielding to compensate for magnetic field distortions and reduce interference
Data Source
AI summary
A hybrid imaging system includes a magnetic resonance scanner and a second modality imaging system disposed in the same radio frequency isolation space. The second modality imaging system includes radiation detectors configured to detect at least one of high energy particles and high energy photons. In some embodiments a retractable radio frequency screen is selectively extendible into a gap between the magnetic resonance scanner and the second modality imaging system. In some embodiments shim coils are disposed with the magnetic resonance scanner and are configured to compensate for distortion of the static magnetic field of the magnetic resonance scanner produced by proximity of the second modality imaging system.