Gamma Camera Pulse Injection Circuit for Source-Free Calibration
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Solution Overview
Problem
Current quality control and performance testing methods for Gamma cameras are cumbersome, requiring radioactive sources and extensive user intervention, which increases costs and reduces available patient imaging time due to the need for secure handling and logistical procedures.
Innovation Solution
A pulse injection circuit is integrated into the Gamma camera using a field programmable gate array to replicate photomultiplier tube output signals, allowing for digital-to-analog conversion, amplification, and injection into the detector circuitry for testing, enabling diagnostic and calibration procedures without a conventional gamma-ray source.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If radioactive sources are used for quality control and performance testing, then accurate calibration and diagnosis can be performed, but operational complexity and cost increase due to secure handling and logistical procedures
Solution Approach 1:
The patent uses a pulse injection circuit to generate artificial pulse signals that replicate the electrical output signals of photomultiplier tubes when they detect gamma rays. These synthetic pulse signals are injected into the detector circuitry to simulate actual gamma ray detection events, thereby copying the calibration and diagnostic functions without requiring radioactive sources.
Solution Approach 2:
The patent replaces the physical radioactive source system with an electronic pulse injection system. Instead of using radioactive materials that require secure handling, storage, and regulatory compliance, the system uses electronically generated pulse signals injected through a circuit board, eliminating the mechanical and safety infrastructure required for radioactive source management.
2Measurement precision
If radioactive sources are used for calibration, then proper diagnostic procedures can be performed, but user intervention and time required increase due to secure handling procedures
Solution Approach 1:
The pulse injection circuit is integrated into the Gamma camera system and can be activated automatically by the quality control software without requiring user physical intervention. The system self-performs calibration and diagnostic testing by electronically injecting pulse signals and analyzing the detector responses, eliminating the need for users to manually handle radioactive sources or perform complex setup procedures.
Solution Approach 2:
The pulse injection circuit pre-generates and injects calibration pulse signals into the detector circuitry before actual patient imaging procedures. This preliminary electronic calibration action can be performed quickly and automatically, preparing the system for optimal performance without requiring time-consuming radioactive source handling and setup procedures.
3Reliability
If conventional gamma-ray sources are used for testing, then detector performance can be evaluated, but operational costs increase due to secure handling and logistical requirements
Solution Approach 1:
The patent employs an inexpensive electronic pulse generation and injection system that can be manufactured and deployed at low cost. The pulse injection circuit uses standard electronic components and integrated circuits that are significantly cheaper than radioactive sources, and the system can be easily replaced or upgraded without the regulatory and logistical costs associated with radioactive material management.
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 method provides a reliable, cost-effective means for troubleshooting and performance testing of Gamma camera detectors, reducing the need for radioactive sources and minimizing user intervention, thus enhancing efficiency and reducing operational costs while maintaining image quality.
Implementation Method 1
The crystal converts high-energy photons (e.g., Gamma rays and X-rays) into visible light (i.e., lower energy photons). When a Gamma ray strikes and is absorbed in the scintillation crystal, the energy of the Gamma ray is converted into flashes of light (i.e., a large number of scintillation photons)
Implementation Method 2
A photo-multiplier tube (PMT), which is optically coupled to the scintillation crystal, detects a fraction of these scintillation photons and produces an output electronic signal. A fraction of the scintillation photons incident on the photocathodes cause an electron to be emitted from the photocathode
Data Source
AI summary
A quality control system and method are provided for troubleshooting and performance testing of detectors in a Gamma camera that includes a field programmable gate array for forming digital words to be converted to a pulse, a test pattern generator for storing the digital words, a digital analog converter for converting the digital words into an analog voltage, an amplifier for amplifying and applying the analog voltage, and an analog multiplexor for accepting the analog voltage. The Gamma camera comprises a collimator, a scintillation crystal, a light guide, a photomultiplier tube, and an electronic circuit.