Photomultiplier Tube Gain Adjustment via Voltage Divider
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Solution Overview
Problem
The inconsistency in gain among photomultiplier tubes (PMTs) used in detectors for centre-of-gravity based imaging methods, such as in PET and SPECT, leads to calculation errors in position and time information due to differences in electrical signal energy, affecting the accuracy of position detection.
Innovation Solution
A method to adjust the gain of PMTs by adjusting the voltage and resistance in the voltage divider circuit, using a digital potentiometer, to ensure consistency in electrical signals outputted by each PMT, thereby improving the accuracy of position detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If gain adjustment is performed using traditional methods (e.g., OP amplifiers), then electrical signal consistency can be improved, but device complexity and cost increase
Solution Approach 1:
The patent extracts the gain adjustment function from traditional external electronic components (OP amplifiers) and integrates it directly into the PMT tube structure. The resistance adjustment component is built into the voltage divider circuit within the PMT, eliminating the need for separate electronic adjustment components and reducing overall device complexity while maintaining signal consistency.
Solution Approach 2:
The patent introduces a resistance adjustment component as an intermediary element within the voltage divider circuit of the PMT. This component serves as a mediator that directly controls the gain of the PMT by adjusting the voltage distribution to the dynode, enabling precise electrical signal consistency without requiring complex external electronic circuits.
2Area of stationary object
If multiple PMTs with different gains are used, then detection coverage can be improved, but position detection accuracy deteriorates due to calculation errors
Solution Approach 1:
The patent changes the electrical parameter (gain) of each PMT individually through integrated resistance adjustment components. By independently adjusting the voltage divider circuit parameters for each PMT, the system maintains consistent electrical signal output across multiple PMTs, thereby ensuring accurate position detection calculations while preserving comprehensive detection coverage.
Solution Approach 2:
The patent applies local quality adjustment by providing individual resistance adjustment components for each PMT tube. Each PMT can be independently tuned to achieve uniform gain characteristics, allowing the system to maintain high position detection accuracy across the entire detection array while preserving the extended coverage provided by multiple PMTs.
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 gain adjustment method ensures consistent electrical signals from PMTs, enhancing the accuracy of position detection in centre-of-gravity based imaging methods without requiring additional electronic components like OP amplifiers, simplifying implementation and reducing costs.
Implementation Method 1
The photodetector may be used to convert the visible light into an electrical signal
Implementation Method 2
The electrons may be progressively multiplied by the dynode of the photomultiplier tube
Data Source
AI summary
A method of adjusting a gain of a detector is provided in the present disclosure. According to an example, whether a gain of a photomultiplier tube in the detector meets a gain determination condition may be determined, where the gain determination condition may indicate that an absolute of a difference between the gain of the photomultiplier tube and a target gain is within a predetermined numerical range. When the gain of the photomultiplier tube does not meet the gain determination condition, a voltage of the photomultiplier tube may be adjusted, such that the gain of the photomultiplier tube meets the gain determination condition.