Silicon Photomultiplier Array PET Detector Design
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Solution Overview
Problem
Conventional PET detectors face limitations in spatial resolution, cost, and compatibility with magnetic fields due to the use of photomultipliers and avalanche photodiodes, while silicon photomultipliers offer advantages but require effective engineering implementation to reduce channel numbers and maintain position, energy, and time information.
Innovation Solution
A PET detector design utilizing a silicon photomultiplier array with a light guide and electronic pre-processing circuits, such as Anger, DPC, and cross-wire circuits, to reduce channel numbers and enhance spatial resolution, time performance, and compatibility with PET/MRI systems.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a photomultiplier is used as the photoelectric conversion device, then a high gain (approximately 10^6) is achieved, but the device complexity and cost increase
Solution Approach 1:
The patent replaces expensive photomultipliers with silicon photomultipliers that can be manufactured using standard semiconductor fabrication processes, making them cheaper and more suitable for mass production while maintaining the required gain performance
Solution Approach 2:
The patent substitutes the vacuum tube-based photomultiplier system with a solid-state silicon photomultiplier system, eliminating the need for vacuum tubes and dynode structures, thereby reducing device complexity and enabling integration with magnetic field environments
2Volume of moving object
If an avalanche photodiode is used, then the device volume is reduced and magnetic field compatibility is improved, but the gain is insufficient (approximately 10^4)
Solution Approach 1:
The patent operates the silicon photomultiplier in Geiger-mode with voltage bias exceeding the breakdown voltage, enabling avalanche multiplication with gains reaching 10^6, thereby resolving the gain insufficiency while maintaining the compact solid-state structure
Solution Approach 2:
The patent uses a silicon-based semiconductor structure with specialized doping and layer configurations to achieve both compact volume and high gain through controlled avalanche breakdown, combining the advantages of solid-state miniaturization with high multiplication capability
3Measurement precision
If a position-sensitive photomultiplier is used to achieve high spatial resolution, then the spatial resolution is improved, but the cost of the PET system increases
Solution Approach 1:
The patent employs silicon photomultipliers that can be manufactured using standard semiconductor fabrication techniques, significantly reducing the cost compared to position-sensitive photomultipliers while achieving comparable or superior spatial resolution through pixelated array configurations
Solution Approach 2:
The patent divides the detection area into multiple pixel elements in the silicon photomultiplier array, with each pixel independently detecting light photons and providing position information, thereby achieving high spatial resolution through segmentation rather than requiring a single complex position-sensitive device
4Loss of time
If a silicon photomultiplier array is used to reduce cost and improve time performance, then the time resolution is improved and cost is reduced, but the number of channels increases
Solution Approach 1:
The patent electrically connects multiple silicon photomultiplier pixels within each detector element, combining their signals to form a single output channel per detector element, thereby reducing the total number of channels while preserving the superior time resolution of individual silicon photomultiplier pixels
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
The solution enables a PET detector with improved spatial resolution, DOI detection, TOF capability, and reduced costs, while maintaining accurate information on photon deposition, and is suitable for PET/MRI dual-mode imaging.
Implementation Method 1
a scintillation crystal configured to convert a gamma photon into a scintillation photon
Implementation Method 2
a light guide coupled to the silicon photomultiplier array, wherein the scintillation crystal, the light guide and the silicon photomultiplier array are coupled by an optical coupling agent in this order
Implementation Method 3
a photoelectric converter configured to convert the scintillation photon into an electrical pulse signal
Implementation Method 4
The avalanche photodiode has a small volume and may be used to design a PET detector with a better spatial resolution
Data Source
Figure 1~2
Figure 3
Figure 4
AI summary
A photoelectric converter comprises a silicon photomultiplier array (5) and a light guide (4) coupled with the silicon photomultiplier array (5). The silicon photomultiplier array (5) is obtained by splicing i×j silicon photomultipliers on a horizontal plane, i and j being both integers greater than or equal to 2. A detector comprises a scintillation crystal (1), an electronics system (3), the light guide (4), and silicon photomultipliers. A scanning apparatus comprises a detecting device and a rack. The detecting device comprises the detector, and the detector comprises the photoelectric converter. The silicon photomultipliers have small sizes and are arranged closely. With an appropriate quantity of silicon photomultipliers of appropriate sizes in combination with a light guide having a suitable shape, a high spatial resolution PET detector can be built, so that spatial resolution of an entire PET system is improved, and it is suitable for building a PET detector having DOI and TOF performance, which can be used for PET/MRI, and the costs are low.