Sub-frame correction for PET quantification accuracy
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Solution Overview
Problem
Current PET imaging technologies face challenges in accurately reconstructing images due to varying count rates over long acquisition sessions, especially with short half-life radiopharmaceuticals, leading to degradation in quantification accuracy and increased radiation exposure.
Innovation Solution
The method involves dividing PET imaging data into sub-frame bins to determine sub-frame singles rates maps, allowing for finer temporal resolution in determining singles rates and calculating instantaneous correction factors for live-time and randoms corrections, which are then applied to reconstruct images with improved accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If multi-station PET imaging protocols are used to image a larger axial range of a patient, then the imaging coverage is improved, but the acquisition time increases substantially to half an hour to an hour or longer
Solution Approach 1:
The patent segments the list mode PET imaging data into multiple sub-frame bins within each frame acquisition time period. This segmentation allows for computation of individual sub-frame dead time correction factors, enabling more precise correction of count rate variations that occur during long multi-station acquisition sessions, thereby resolving the contradiction between extended imaging coverage and acquisition time
2Object-affected harmful factors
If the radiopharmaceutical dosage is reduced to minimize radiation exposure, then patient safety is improved, but the count rate becomes low requiring longer acquisition times
Solution Approach 1:
The patent changes the parameter of temporal resolution by computing dead time correction factors at sub-frame level rather than at the full frame level. This finer temporal resolution allows accurate correction of count rate variations even when using low radiopharmaceutical dosages, enabling shorter acquisition times while maintaining image quality and minimizing radiation exposure
3Device complexity
If a single dead time correction factor is computed for single station imaging, then the computation is simplified, but the quantification accuracy degrades when count rate varies significantly over the imaging session
Solution Approach 1:
The patent implements a dynamic correction approach where dead time correction factors are computed for multiple sub-frames within each frame acquisition time period. This dynamic, time-varying correction adapts to changing count rates during the imaging session, improving quantification accuracy while maintaining computational feasibility through the sub-frame segmentation approach
Data Source
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AI summary
A non-transitory computer-readable medium stores instructions readable and executable by a workstation (18) including at least one electronic processor (20) to perform an image reconstruction method (100) to reconstruct list mode data acquired over a frame acquisition time using a plurality of radiation detectors (17) in which the events of the list mode data is timestamped. The method includes: for the sub-frame bins of a plurality of sub-frame bins into which the frame acquisition time is divided, determining a sub-frame singles rates map for the plurality of radiation detectors from the list mode data whose time stamps reside in the sub-frame bin; determining a singles rate for the singles events of the list mode data using the sub-frame singles rates maps wherein the singles rates for the singles events are determined at a temporal resolution that is finer than the frame acquisition time; determining correction factors for the list mode data using the determined singles rates for the singles events of the list mode data; and reconstructing the list mode data of the frame acquisition time using the determined correction factors to generate a reconstructed image for the frame acquisition time.