PET Event Timing Correction for Sub-LSB Image Reconstruction
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Solution Overview
Problem
Nuclear imaging systems face inaccuracies in timing information due to mechanical limitations, leading to reduced accuracy in image reconstruction, particularly in PET systems, as conventional corrections fail to account for precise timing delays.
Innovation Solution
Implementing a system that shifts and corrects timing data using additional bits to achieve finer resolution, allowing for more accurate timing alignment by applying a timing correction model to generate sub-LSB TDC times, which are stored and used for image reconstruction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional timing correction methods are used in PET systems, then the system complexity remains manageable, but the timing precision and image reconstruction accuracy are insufficient
Solution Approach 1:
The patent extends the timing data from 16 bits to 24 bits, adding 8 additional bits of precision. This dimensional expansion in the data representation space enables sub-LSB timing corrections, achieving finer timing resolution without requiring a complete redesign of the detection hardware.
Solution Approach 2:
The patent pre-calculates and stores timing correction values in lookup tables before actual image reconstruction. By performing the complex correction calculations in advance and storing them for rapid retrieval, the system achieves high timing precision during reconstruction without real-time computational overhead.
2Measurement precision
If 16-bit timing data is used from TDC, then the data processing is simple, but the timing resolution is insufficient for accurate event time difference measurement
Solution Approach 1:
The patent adds 8 bits to the original 16-bit timing data to create 24-bit timing data. This extension provides sub-LSB timing resolution, enabling measurement of event time differences with precision finer than the original TDC least significant bit, thereby recovering timing information that would otherwise be lost.
Solution Approach 2:
The patent introduces timing correction values as an intermediary layer between the raw TDC timing data and the final image reconstruction. These correction values, stored in lookup tables, mediate the transformation by compensating for timing delays and skew, enabling accurate timing measurement without modifying the original TDC hardware.
3Measurement precision
If timing correction is not applied, then the processing speed is fast, but the image reconstruction accuracy deteriorates due to timing errors
Solution Approach 1:
The patent performs timing correction calculations in advance and stores the results in lookup tables. During actual image reconstruction, the system simply retrieves pre-computed correction values, achieving high accuracy without real-time computational burden, thus maintaining fast processing speed.
Solution Approach 2:
The patent creates lookup tables that contain copies of timing correction values for different detector element combinations. Instead of calculating corrections on-the-fly during reconstruction, the system copies and applies pre-stored correction values, dramatically speeding up processing while maintaining accuracy.
Data Source
AI summary
Systems and methods for correcting timing information associated with captured nuclear imaging data, and for reconstructing medical images based on the corrected timing information, are disclosed. In some embodiments, an image scanning system scans a subject, detects an event, and generates timing data for the detected event. The timing data includes a first number of bits, and characterizes a time that a crystal of the image scanning system detected the event. The image scanning system shifts the first number of bits by a predetermined amount to generate a second number of bits, where the second number of bits includes at least one bit representing a lower order time value than the least significant bit of the first number of bits of the timing data. Further, the image scanning system generates timing correction data for the event based on the second timing data.