Movable PET Detector Axial Positioning in MRI Bore
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Solution Overview
Problem
Fixed positions of PET detectors in PET-MRI apparatuses often interfere with the high power RF magnetic fields of MRI systems, leading to data acquisition issues and limitations in combined imaging protocols.
Innovation Solution
A moving mechanism for the PET detector that allows it to move along the axial direction of the bore, positioning it away from the magnetic field center, reducing interference and enhancing the flexibility of imaging protocols.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the PET detector is fixed in the vicinity of the magnetic field center, then the PET detector can be easily positioned and integrated with the MRI apparatus, but it interferes with the high power RF magnetic fields and RF coils, causing data acquisition problems
Solution Approach 1:
The PET detector is made movable along the axial direction of the bore through a moving mechanism, allowing it to dynamically adjust its position. This resolves the contradiction by enabling the detector to be positioned away from the magnetic field center during operation, reducing interference with RF fields while maintaining ease of integration through the designed moving structure
Solution Approach 2:
The PET detector is divided into multiple detector modules that can be independently positioned and moved. This segmentation allows flexible arrangement of detector modules at optimal positions away from the magnetic field center, reducing interference while maintaining integration capability
2Object-affected harmful factors
If the PET detector is moved away from the magnetic field center, then interference with RF magnetic fields is reduced, but the device complexity increases due to the moving mechanism
Solution Approach 1:
A moving mechanism is provided to enable the PET detector to move along the axial direction of the bore. This dynamic positioning capability reduces interference with RF magnetic fields by allowing the detector to be positioned away from the magnetic field center, while the mechanism is designed to manage the added complexity through integrated drive systems and control mechanisms
3Device complexity
If the PET detector position is fixed, then the device structure is simple, but the flexibility in establishing combined PET-MRI imaging protocols is limited
Solution Approach 1:
The movable PET detector positioned along the axial direction enables flexible adjustment of the detection region, allowing adaptation to various imaging protocols and examination requirements while maintaining a relatively simple overall device structure through the linear moving mechanism
Solution Approach 2:
The PET detector is moved along the axial direction (adding positional variability in the axial dimension), which provides new degrees of freedom for configuring imaging protocols and examining different body regions without fundamentally complicating the device structure
Data Source
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AI summary
A positron emission tomography (PET)-magnetic resonance imaging (MRI) apparatus (100) according to an embodiment includes a gantry having a static magnetic field magnet (1), a gradient coil (3), and a radio frequency coil (5), a PET detector (13, 13a, 13b, 13c), and a moving mechanism (20, 20a, 20b, 20c). The static magnetic field magnet (1) generates a static magnetic field in a bore having an approximately cylindrical shape. The gradient coil (3) is disposed on an inner circumference side of the static magnetic field magnet (1) and applies a gradient magnetic field to an object disposed in the bore. The radio frequency coil (5) is disposed on an inner circumference side of the gradient coil (3) and applies a radio frequency magnetic field to the object. The PET detector (13, 13a, 13b, 13c) detects gamma rays emitted from a positron-emitting radionuclide injected into the object. The moving mechanism (20, 20a, 20b, 20c) causes the PET detector (13, 13a, 13b, 13c) in the gantry along the axial direction of the bore.