PET Detector ToF Kernel Customization via Photon Statistics
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Solution Overview
Problem
In Positron Emission Tomography (PET) image reconstruction, the quality of reconstructed images is degraded when the time width of the Time of Flight (ToF) kernel does not match the ToF capabilities of detectors, and making detector capabilities uniform is costly.
Innovation Solution
A nuclear medicine diagnosis apparatus calculates a ToF kernel for each detector based on a light emission model, specifying a probability distribution model related to detection time differences along a Line Of Response (LOR) defined by the detectors, to absorb variance in capabilities and enhance image quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the time width of the ToF kernel is adjusted to match detector capabilities, then image quality is improved, but detector uniformity becomes difficult to achieve
Solution Approach 1:
The patent applies local quality by calculating individual ToF kernels for each detector based on its specific light emission characteristics. Instead of using a uniform ToF kernel for all detectors, the system determines detector-specific parameters (mean and standard deviation) from photon number information, allowing each detector to have a customized ToF kernel that matches its unique capabilities, thereby improving image quality without requiring detector uniformity
Solution Approach 2:
The patent changes parameters by deriving detector-specific ToF kernel parameters (mean time difference and standard deviation) from measured photon number information. The system calculates these parameters individually for each detector and uses them to create customized ToF kernels, transforming the approach from using fixed uniform parameters to using dynamically determined detector-specific parameters
2Measurement precision
If detector capabilities are made uniform, then image quality is improved, but cost increases significantly
Solution Approach 1:
The patent applies self-service by enabling each detector to characterize its own capabilities through measuring photon number information from light sources. The system allows detectors to self-determine their individual ToF kernel parameters without requiring expensive external calibration equipment or uniformity adjustment mechanisms, thereby improving image quality while avoiding the high costs associated with making detector capabilities uniform
3Device complexity
If a single ToF kernel is used for all detectors, then device complexity is reduced, but image quality deteriorates
Solution Approach 1:
The patent applies segmentation by dividing the ToF kernel configuration into detector-specific components. Instead of using a single unified ToF kernel for all detectors, the system segments the kernel parameters (mean and standard deviation) to be calculated individually for each detector based on its specific photon number characteristics, thereby improving image quality while maintaining manageable system complexity through automated calculation
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 allows for enhanced image quality by matching ToF capabilities of detectors with the ToF kernel, even when there is variance among detectors, without the high cost of uniforming detector capabilities.
Implementation Method 1
obtain first photon number information detected by a first detector and second photon number information detected by a second detector different from the first detector
Data Source
AI summary
A nuclear medicine diagnosis apparatus according to an embodiment includes processing circuitry. The processing circuitry is configured: to obtain first photon number information detected by a first detector and second photon number information detected by a second detector different from the first detector; to calculate a first light emission probability model corresponding to the first detector on the basis of the first photon number information and a second light emission probability model corresponding to the second detector on the basis of the second photon number information; and to specify a probability distribution model related to a detection time difference along a Line Of Response (LOR) defined by the first detector and the second detector, on the basis of the first light emission probability model and the second light emission probability model.