Delta Map Calibration for Non-Pixelated Gamma Detectors
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Solution Overview
Problem
Non-pixelated gamma cameras require frequent recalibration due to aging and repairs, leading to inaccuracies in linearity and uniformity maps, which results in poor image quality and time-consuming recalibration processes for each isotope detected.
Innovation Solution
A method is developed to create calibration maps for non-pixelated gamma detectors by determining a delta map based on the relationship between a reference isotope and another isotope, allowing for the transformation of calibration maps, thereby reducing the need for extensive recalibration of each isotope.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If recalibration is performed for each isotope during initial calibration, then measurement precision is improved, but loss of time increases significantly
Solution Approach 1:
The patent pre-calculates delta maps during initial calibration that represent the relationship between reference isotope and other isotopes. These delta maps are stored and later applied during recalibration to avoid time-consuming full recalibration for each isotope, thus maintaining precision while reducing time loss
Solution Approach 2:
Instead of performing complete recalibration for each isotope, the patent creates simplified delta map copies that capture the essential calibration relationships. These delta maps are applied to transform the reference calibration map to other isotope calibration maps, significantly reducing recalibration time while maintaining accuracy
2Reliability
If complete recalibration is performed for each isotope, then reliability is improved, but productivity decreases due to time consumption
Solution Approach 1:
The patent segments the calibration process into two parts: a reference calibration map obtained through complete recalibration, and delta maps that capture the differences between reference and other isotopes. This segmentation allows efficient updates by only recalibrating the reference while maintaining reliability through pre-computed delta relationships
Solution Approach 2:
The reference calibration map serves multiple functions as a base for generating calibration maps for different isotopes. By making the reference map universal and using delta maps to adapt it to specific isotopes, the system maintains reliability across multiple isotopes while improving productivity through reduced recalibration requirements
3Measurement precision
If calibration maps are updated for each isotope, then measurement precision is maintained, but device complexity increases
Solution Approach 1:
The patent introduces delta maps as intermediary elements that mediate between the reference calibration map and isotope-specific calibration requirements. These delta maps simplify the complexity by providing a standardized transformation mechanism rather than requiring separate complete calibration procedures for each isotope
4Reliability
If frequent recalibration is performed, then reliability is improved, but loss of time increases
Solution Approach 1:
The patent performs preliminary calculation of delta maps during initial calibration that anticipate future recalibration needs. This preliminary action enables frequent recalibration when necessary while minimizing time loss, as the delta maps are already prepared and can be quickly applied to update calibration for multiple isotopes simultaneously
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 approach significantly reduces recalibration time and maintains image quality by allowing calibration maps to be updated efficiently using delta maps, specifically for linearity and uniformity corrections, without the need for recalibration of each isotope.
Implementation Method 1
a single crystal scintillator formed from Sodium Iodide (NaI). During a gamma event, light emissions from the crystal are detected by an array of photomultiplier tubes (PMTs)
Implementation Method 2
light emissions from the crystal are detected by an array of photomultiplier tubes (PMTs) to create a signal
Data Source
AI summary
A method for calibrating a non-pixelated gamma camera is provided, wherein the method includes determining a linearity map and a uniformity map of a reference isotope; and determining a linearity map and uniformity map of another isotope. Delta maps are calculated based on the maps of the reference isotope and the maps of the other isotope. During recalibration, new maps of the reference isotope are determined, thereby enabling new maps of the other isotope to be created based on the delta maps.