PET Scanner Background Correction Using Multiple Coincidence Events
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Solution Overview
Problem
Current PET scanners face challenges in distinguishing prompt gamma rays from annihilation gamma rays when using advanced radionuclides, leading to spurious coincidences that reduce image contrast and quantitative accuracy due to inadequate energy resolution and background correction methods.
Innovation Solution
A system and method that utilize multiple coincidence events to separate standard and non-standard lines of response, allowing for direct measurement and correction of background caused by prompt gamma rays, improving image quality without requiring additional detector elements or excessive computational time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional PET scanners use standard energy resolution detectors, then device complexity is low, but measurement precision deteriorates due to inability to distinguish prompt gamma rays from annihilation gamma rays
Solution Approach 1:
The patent uses multiple coincidence events as an intermediary to indirectly identify and correct spurious coincidences. Instead of requiring detectors to directly distinguish between prompt gamma rays and annihilation gamma rays through high energy resolution, the method employs temporal and spatial patterns of multiple detected photons to identify spurious events and subtract their contribution from the image data.
2Illumination intensity
If background correction methods are applied to remove spurious coincidences, then image contrast improves, but loss of time increases due to computational processing requirements
Solution Approach 1:
The patent performs background correction during the image reconstruction process itself, rather than as a separate post-processing step. By integrating the spurious coincidence subtraction into the iterative reconstruction algorithm, the method efficiently utilizes the computational work already being performed for image formation, thereby minimizing additional processing time while effectively removing background.
3Quantity of substance
If advanced radionuclides emitting prompt gamma rays and positrons are used, then quantity of substance imaged increases, but object-generated harmful factors worsen due to spurious coincidences reducing image quality
Solution Approach 1:
The patent converts the harmful effect of prompt gamma rays into a useful signal by detecting multiple coincidence events. The presence of prompt gamma rays creates additional detected photons that, when analyzed in multiple coincidence patterns, provide information about spurious coincidence locations. This information is then used to subtract background, ultimately improving image quality while enabling the use of advanced radionuclides.
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 image quality and sensitivity by accurately removing spurious background, reducing noise, and increasing contrast in PET images, while being faster and less prone to bias compared to existing methods.
Implementation Method 1
Block detectors 102 include a piece of scintillator material that converts the energy deposited by gamma rays into visible light
Implementation Method 2
The scintillator material is usually segmented into many scintillation crystal elements configured in an array, which is read out by one or more photon detectors (such as a number of individual photo-multiplier tubes (PMTs)) that convert the light emitted by the scintillation material into electrical signals
Implementation Method 3
These radionuclides are denominated 'conventional' because they decay by emitting only positrons. The positrons travel a very short distance before they encounter an electron and, when this occurs, the positrons are annihilated and converted into two photons, or gamma rays
Data Source
AI summary
A method and system for acquiring a series of medical images includes a plurality of detectors configured to be arranged to acquire gamma rays emitted from a subject as a result of an advanced radionuclide administered to the subject and communicate signals corresponding to acquired gamma rays. A data processing system is configured to receive the signals from the plurality of detectors, determine double coincidence event dataset and a multiple coincidence event dataset, separate the multiple coincidence event dataset into at least one of a standard lines of response dataset and a nonstandard lines of response dataset, and apply a background correction to the double coincidence event dataset based on the non-standard lines of response dataset and/or the standard lines of response dataset to obtain a standard coincidence dataset.