PET Scanner Coincidence Window Adaptation
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Solution Overview
Problem
Current PET imaging systems use a uniform coincidence time window for all lines of response (LORs), which can be too large for shorter LORs, leading to errors in determining coincidence events and reduced imaging quality.
Innovation Solution
A system and method that determine multiple coincidence window width values based on specific characteristics of each LOR, such as length and incident angle, to improve the accuracy of coincidence event detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a uniform coincidence time window is set for all LORs based on the longest LOR, then the system can cover all possible LORs, but the coincidence time window becomes too large for shorter LORs, resulting in errors in determining coincidence events and reduced imaging quality
Solution Approach 1:
The patent segments the coincidence time window setting into multiple discrete values corresponding to different LOR length ranges. Instead of using a single uniform time window for all LORs, the system divides LORs into several length categories and assigns appropriate coincidence time window values to each category, thereby resolving the contradiction between coverage and precision.
Solution Approach 2:
The patent applies local quality by making the coincidence time window parameter adaptive to local characteristics of each LOR. Specifically, shorter LORs are assigned smaller coincidence time windows while longer LORs receive larger windows, allowing each LOR to have an optimized time window matched to its specific geometry rather than using a uniform global setting.
2Ease of manufacture
If a uniform coincidence time window is used for all LORs, then the system configuration is simple, but the imaging quality deteriorates due to incorrect coincidence determination for shorter LORs
Solution Approach 1:
The patent changes the coincidence time window parameter based on LOR length characteristics. The system automatically selects appropriate coincidence time window values from a set of predefined options based on the measured LOR length, thereby improving imaging precision without requiring complex manual configuration.
3Measurement precision
If multiple coincidence time window values are determined based on LOR characteristics, then the precision of coincidence event identification improves, but the system complexity increases
Solution Approach 1:
The patent performs preliminary action by pre-establishing a mapping relationship between LOR length ranges and coincidence time window values. This mapping table is prepared in advance, allowing the system to quickly determine appropriate time windows during operation without complex real-time calculations, thus improving precision while controlling system complexity.
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 enhances the precision and efficiency of identifying true coincidence events, reduces random events, and improves image quality by tailoring the coincidence time window to the specific geometry of each LOR.
Implementation Method 1
A tiny difference between the times when the two photons are detected may depend on the location of the annihilation position on the LOR. During a process for determining a coincidence event, when a first detector unit detects a first photon, a coincidence time window may be set for the other photon.
Data Source
AI summary
A method for positron emission tomography (PET) imaging may include obtaining photon information of photons that are emitted from an object and detected by detector units of a detector of a PET scanner. The method may also include obtaining, based on the photon information and lines of response (LORs), more than one coincidence window width value of the PET scanner. The method may also include determining coincidence events of the photons based on the more than one coincidence window width value.