Shielded PET Detector Layout for Integrated PET/MRI Imaging
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Solution Overview
Problem
Existing PET scanners integrated with MRI scanners face challenges such as interference from electromagnetic fields, spatial resolution issues, and complexity due to the need for electromagnetic shielding and large size, which hinder high-resolution imaging.
Innovation Solution
A PET detector with electromagnetic shielding and a non-parallel scanning direction to the MRI scanner's main axis, using semiconductor detectors and slots perpendicular to the MRI scanner's axis to prevent induced currents, allowing integration within the MRI scanner.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If electromagnetic shielding is added to protect PET detector from MRI electromagnetic fields, then reliability of PET detection is improved, but device complexity and size increase
Solution Approach 1:
The PET detector is nested within the MRI scanner bore, with the shielding structure integrated into the existing MRI scanner framework. The shielding is positioned between the PET detector and MRI components, utilizing the spatial arrangement where the PET detector operates within the confined space of the MRI scanner without requiring separate external shielding structures.
Solution Approach 2:
A slot structure is introduced as an intermediary element in the shielding design. These slots allow electromagnetic fields to pass through selectively while maintaining the overall shielding function, reducing the burden on the PET detector electronics and simplifying the shielding structure by creating controlled field pathways rather than complete barriers.
2Measurement precision
If photomultiplier tubes are used for high-resolution PET detection, then measurement precision is improved, but device size and weight increase
Solution Approach 1:
The invention changes the detection parameter from optical photon detection (requiring photomultiplier tubes) to direct gamma photon interaction with semiconductor material. This parameter change enables the use of compact semiconductor detectors that directly convert gamma radiation into electrical signals, eliminating the need for bulky photomultiplier tubes while maintaining detection capability.
3Productivity
If PET scanner is integrated within MRI scanner, then productivity of combined imaging is improved, but harmful electromagnetic interference increases
Solution Approach 1:
The shielding structure is segmented into multiple sections with slots distributed throughout. This segmentation allows different regions of the shielding to handle different aspects of electromagnetic field management, with slots strategically positioned to protect sensitive electronics while maintaining overall system functionality and enabling simultaneous PET/MRI operation.
4Area of stationary object
If scanning direction is made non-parallel to MRI main axis, then spatial constraints are reduced, but device complexity increases
Solution Approach 1:
The PET detector scanning direction is deliberately oriented asymmetrically relative to the MRI scanner main axis. This asymmetric arrangement optimizes the spatial configuration to minimize interference patterns and create favorable geometric relationships between the two imaging systems, reducing the need for complex active compensation mechanisms.
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
Enables high-resolution PET and MRI scans with reduced interference and spatial constraints, facilitating simultaneous imaging without damaging electronics or increasing device size.
Implementation Method 1
The PET detector has shielding against electromagnetic fields, such that electromagnetic fields generated by the MRI scanner are kept away from the PET detector, and electromagnetic fields from the PET detector's processing electronics are kept away from a receiver coil of the MRI scanner.
Implementation Method 2
The shielding of the PET detector has at least one slot that is perpendicular to the main axis of the MRI scanner in at least one projection to prevent induced currents.
Implementation Method 3
using semiconductor detectors
Data Source
Figure 1
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AI summary
The invention relates to a PET-detector (2) for a combined PET/MRI-scanner (1), said PET-detector (2) comprising a shielding (ES) against electromagnetic fields, such that electromagnetic fields generated by the MRI-scanner (3) are kept away from the PET-detector (2), and such that electromagnetic fields of the processing electronics of the PET-detector (2) are kept away from a receiver coil of the MRI-scanner (3), wherein the PET-detector (2) is suitable for use within the MRI-scanner (3), wherein the scanning unit (B) of the PET detector (2) is oriented substantially not in parallel with the main axis (A) of the MRI-scanner (3), wherein the shielding (ES) of the PET-detector (2) has at least one slot (S1; S2), which is perpendicular to the main axis of the MRI-scanner (A) at least in one projection, in order to prevent induced currents.