Monolithic PET Detector with Refractive Index-Matched Side Coating
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Solution Overview
Problem
Current PET scanners face challenges in achieving high spatial resolution and cost-effectiveness due to the use of segmented scintillation crystals, which are complex and expensive to produce, and suffer from parallax errors and reduced sensitivity, especially in systems with small ring diameters.
Innovation Solution
A monolithic radiation detector design featuring a monolithic scintillation crystal with a refractive index-matched material on its side surfaces, allowing for controlled light reflection and enabling the use of all photodetectors for data processing without edge area limitations, thereby maintaining resolution and sensitivity across the entire detector area.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If segmented scintillation crystals are used to achieve high spatial resolution, then measurement precision is improved, but device complexity and manufacturing cost increase significantly
Solution Approach 1:
The patent merges multiple crystal segments into a single monolithic scintillation crystal. This monolithic crystal is coupled to an array of photodetectors, eliminating the need for complex segmentation while maintaining the ability to achieve high spatial resolution through the integrated structure and light distribution patterns.
Solution Approach 2:
The patent changes the physical parameter of the scintillation crystal from segmented to monolithic form. This fundamental structural parameter change simplifies manufacturing and assembly while enabling new approaches to achieving spatial resolution through light transport and detection patterns across the photodetector array.
2Measurement precision
If segmented scintillation crystals are used to improve spatial resolution, then measurement precision is improved, but production cost increases by a factor of 3-5
Solution Approach 1:
The patent combines multiple crystal segments into one monolithic crystal structure. This merging eliminates the need for precise alignment and assembly of multiple segments, significantly simplifying the manufacturing process and reducing production costs while maintaining high spatial resolution capabilities.
Solution Approach 2:
The patent employs a monolithic crystal design that is simpler and less expensive to manufacture than segmented crystals. The single-crystal structure reduces material waste, assembly complexity, and quality control requirements, making the system more cost-effective despite achieving comparable or superior performance.
3Measurement precision
If segmented scintillation crystals are used to achieve high spatial resolution, then measurement precision is improved, but sensitivity decreases due to reduced available sensor area
Solution Approach 1:
The patent merges the crystal structure into a monolithic form that maximizes the coupling area with the photodetector array. This eliminates gaps and intermediate layers between segments, ensuring that the entire sensor area is effectively utilized for detection, thereby maintaining high sensitivity while achieving fine spatial resolution.
4Device complexity
If monolithic scintillation crystal is used to reduce cost and complexity, then device complexity is reduced, but edge area reflections make it difficult to determine three-dimensional interaction position
Solution Approach 1:
The patent applies different optical properties to different regions of the monolithic crystal. By creating lateral variations in the refractive index or light absorption characteristics across the crystal face, the system can distinguish between light originating from different depths and locations, enabling accurate three-dimensional position determination despite the monolithic structure.
Solution Approach 2:
The patent introduces an intermediate optical layer or coating on the crystal surface that mediates the light reflection problem. This intermediate layer modifies the light transport paths from edge regions, reducing spurious reflections and improving the accuracy of interaction position determination while maintaining the benefits of the monolithic structure.
5Adaptability or versatility
If small ring diameter PET scanners are used for organ-specific examinations, then adaptability is improved, but parallax errors increase due to off-center decay locations
Solution Approach 1:
The patent utilizes depth-of-interaction (DOI) information by analyzing the light distribution patterns across the photodetector array. This enables the system to determine the depth and lateral position of gamma interactions, correcting for parallax errors and maintaining high spatial accuracy even in small ring diameter configurations optimized for organ-specific examinations.
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 design enhances spatial resolution, reduces production costs, and improves sensitivity by allowing reliable data processing in the edge regions, leading to more efficient data handling and lower power consumption, while maintaining comparable sensitivity to the central area.
Implementation Method 1
A large part of previous PET scanners is based on the fact that the two high-energy photons (gamma photons) are stopped in crystals in which a scintillation process generates optical photons.
Implementation Method 2
The photons are then recorded by optical sensors and converted into electrical impulses.
Implementation Method 3
A monolithic radiation detector design featuring a monolithic scintillation crystal with a refractive index-matched material on its side surfaces, allowing for controlled light reflection
Data Source
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AI summary
The invention relates to a monolithic radiation detector (1) for a PET scanner, having a monolithic scintillation crystal (K) and a 1-dimensional arrangement of at least 2 photodetectors (PD1, PD2), wherein the scintillation crystal (K) has a refractive index for a given light, wherein the 1-dimensional arrangement of at least 2 photodetectors (PD1, PD2) is arranged parallel to a first area (F1) of the monolithic scintillation crystal, wherein the opposite second area (F2) represents an entry area for gamma quanta of a positron-electron annihilation, wherein the crystal (K) has at least one lateral area (S1), which has at least one normal vector of the first area and/or of the second area as a spanning vector, wherein the lateral area (S1) has, at least on the boundary to the scintillation crystal (K), a material (M) having approximately the same refractive index as the refractive index of the scintillation crystal, wherein the material (M) of the lateral area has no scintillation effect according to the scintillation crystal.