PET Detector Sensitivity Correction for Non-Circular Arrangements
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Solution Overview
Problem
Conventional element-by-element sensitivity correction methods in PET devices fail when detector arrangements are flexible and non-circular, leading to artifacts in reconstructed images due to variable positional relations and changing geometric factors.
Innovation Solution
A sensitivity correction method that calculates sensitivity coefficients in three steps: first, based on sensitivity factors; second, the non-geometric factor before arrangement changes; and third, derived from geometrical arrangement changes, using coincidence counting data to correct sensitivities and prevent artifacts in flexible PET apparatuses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the conventional element-by-element sensitivity correction method is used with fixed circular detector arrangement, then the sensitivity correction can be performed using geometric symmetry, but the method becomes invalid when detector arrangement is variable and non-circular, leading to artifacts in reconstructed images
Solution Approach 1:
The patent changes the fundamental parameter of sensitivity correction from geometric-factor-based (assuming circular symmetry) to coincidence-counting-data-based (empirical measurement). By using actual coincidence counting data collected during calibration scans, the system adapts to any detector arrangement configuration without relying on geometric assumptions, thereby resolving the contradiction between adaptability to variable arrangements and correction accuracy
Solution Approach 2:
The patent creates a virtual model of the actual detector response by collecting coincidence counting data that replicates real measurement conditions. This empirical data copy replaces the theoretical geometric factors, allowing the sensitivity correction to accurately reflect the actual detector performance regardless of arrangement variations
2Measurement precision
If the direct method is used to obtain sensitivity coefficients for all detector pairs, then all sensitivity coefficients are directly obtained, but the number of sensitivity coefficients becomes enormous and statistical accuracy per pair is lowered
Solution Approach 1:
The patent merges the sensitivity information of multiple detector pairs into a single sensitivity map by using coincidence counting data from a uniform cylindrical calibration source. Instead of calculating individual coefficients for each detector pair, the method combines all measurements into a unified correction framework that reduces the number of parameters while maintaining accuracy
Solution Approach 2:
The patent creates a universal sensitivity correction approach that works for all detector pairs simultaneously using a single set of coincidence counting measurements. The correction method is designed to be applicable across the entire detector array regardless of specific pair configurations, reducing complexity while maintaining comprehensive coverage
Data Source
AI summary
Sensitivity correction for multiple γ radiation detectors is performed by use of sensitivity coefficients obtained through a first sensitivity coefficient calculation step for obtaining sensitivity coefficients, classified according to sensitivity factors, on the basis of coincidence counting data collected as a result of detection of γ radiation emitted from a rotated rod-shaped calibration radiation source, and through a third sensitivity coefficient calculation step for obtaining sensitivity coefficients derived from a geometrical arrangement on the basis of coincidence counting data collected in a state where arrangement of the γ radiation detectors is changed. A re-constructed image is obtained on the basis of data acquired after the sensitivity correction is finished.