SiPM Readout Circuit for High-Resolution Gamma Ray Position Detection
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Solution Overview
Problem
Nuclear medicine diagnosis apparatuses face challenges in achieving high-resolution imaging due to the large number of read circuits required for accurate gamma ray position detection, which increases the size and cost of the apparatus, and deteriorates the timing properties of the detection signal, especially with the use of multiplexed SiPMs.
Innovation Solution
A radiation detection device with a plurality of scintillators and semiconductor light-receiving devices, where a position detection circuit and a timing detection circuit share the same electrical signal from the anode, and a centroid calculation circuit generates weighting addition signals to specify the gamma ray detection position, while a capacitor connected to the timing detection circuit improves high-frequency component detection, reducing the number of required read circuits and maintaining accurate timing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If an individual read circuit is provided in each light-receiving device to improve position detection accuracy, then the position detection accuracy is improved, but the device complexity and cost increase significantly
Solution Approach 1:
Multiple light-receiving devices (SiPMs) are electrically connected in parallel to share a common read circuit. This merging approach allows a single read circuit to process signals from multiple SiPMs simultaneously, significantly reducing the total number of read circuits required while maintaining position detection capability through centroid calculation algorithms.
Solution Approach 2:
The common read circuit is designed to handle signals from multiple light-receiving devices through parallel connection. The circuit performs universal signal processing functions including amplification, filtering, and centroid calculation for position detection, serving multiple SiPMs with a single multi-functional unit rather than requiring dedicated circuits for each device.
2Device complexity
If multiple light-receiving devices are connected in parallel to reduce the number of read circuits, then the device complexity is reduced, but the timing property of the detection signal deteriorates
Solution Approach 1:
A capacitor is introduced as an intermediary element in the parallel connection of multiple SiPMs. This capacitor serves as a signal processing mediator that preserves high-frequency components of the detection signal while allowing multiple SiPMs to share the common read circuit. The capacitor filters out low-frequency noise and maintains signal integrity for accurate timing detection despite the parallel connection configuration.
Solution Approach 2:
The electrical characteristics of the parallel connection are optimized by adjusting parameters such as capacitance values and resistance values in the circuit. By carefully selecting these parameters, the circuit maintains appropriate bandwidth and timing resolution while accommodating multiple parallel-connected SiPMs, thus preserving timing detection accuracy despite the reduced number of read circuits.
3Device complexity
If the number of read circuits is reduced to decrease apparatus size and cost, then the device complexity and cost are reduced, but the position detection accuracy deteriorates
Solution Approach 1:
The patent replaces the traditional mechanical/electrical approach of using individual read circuits for each SiPM with a signal processing approach. By using centroid calculation algorithms on the electrical signals from parallel-connected SiPMs, the system achieves position detection functionality without requiring proportional hardware resources, thus reducing device complexity while maintaining accuracy through computational methods.
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 enhances position detection accuracy and time detection accuracy while suppressing deterioration in the timing property of the detection signal, thereby improving the overall performance of the nuclear medicine diagnosis apparatus without significantly increasing its size or cost.
Implementation Method 1
a scintillator that receives a gamma ray and converts the received gamma ray into fluorescence
Implementation Method 2
a light-receiving device that multiplies a photoelectron from the scintillator and converts the multiplied photoelectron into an electrical signal
Data Source
AI summary
A radiation detection device (300) is used in a nuclear medicine diagnosis apparatus, and includes a plurality of scintillators (44), a semiconductor light-receiving device (SiPM), a position detection circuit (214), and a timing detection circuit (216). Each of the scintillators converts a gamma ray emitted from a subject (15) into fluorescence. The semiconductor light-receiving device is provided corresponding to each of the scintillators and converts the fluorescence converted by a corresponding one of the scintillators into an electrical signal. The position detection circuit specifies a gamma ray detection position in the scintillators based on the electrical signal from the semiconductor light-receiving device. The timing detection circuit is connected to an anode of the semiconductor light-receiving device, and specifies time information corresponding to a time of occurrence of an event in which the gamma ray is detected.