Nested Scintillator PET Detector for TOF Resolution
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Solution Overview
Problem
Conventional PET devices face challenges in reducing the thickness of scintillators to improve time-of-flight temporal resolution while maintaining image quality, as thinner scintillators increase the likelihood of gamma rays passing undetected, degrading image quality.
Innovation Solution
A PET device configuration with two layers of scintillators, where the inner detector has a higher scintillator density and thinner dimensions to enhance image quality, and the outer detector has a lower density and larger pixel size to reduce manufacturing costs, with an energy value adder and simultaneous counted information generator to compensate for undetected gamma rays.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If the thickness of scintillators is reduced to improve TOF temporal resolution, then time resolution is improved, but the detection probability of gamma rays decreases
Solution Approach 1:
The patent implements a nested detector structure where an inner PET detector with thin scintillators is placed inside an outer PET detector with thicker scintillators. The outer detector acts as a backup to catch gamma rays that pass through the inner detector, effectively nesting one detection system within another to solve the detection probability problem while maintaining thin inner scintillators for good time resolution.
Solution Approach 2:
The patent transitions from a single-layer detector to a two-layer detector configuration, adding the radial dimension of detection depth. By stacking detectors at different radial positions, the system captures gamma rays that would otherwise pass through, effectively using an additional spatial dimension to solve the detection probability issue.
2Loss of time
If the thickness of scintillators is reduced to improve TOF temporal resolution, then time resolution is improved, but image quality decreases
Solution Approach 1:
The nested detector configuration allows the inner thin scintillators to provide excellent time resolution while the outer thicker scintillators provide backup detection capability, ensuring that image quality is maintained through combined data from both layers even when inner scintillators are thin.
Solution Approach 2:
The patent changes the parameter distribution by making inner scintillator thickness smaller and outer scintillator thickness larger, creating a non-uniform thickness profile across the detector radius. This parameter optimization allows the system to achieve both good time resolution from thin inner scintillators and adequate detection probability from the combined system.
3Reliability
If scintillator density is increased to improve detection probability, then detection probability increases, but manufacturing cost increases
Solution Approach 1:
The patent applies local quality by creating different scintillator densities at different radial positions: high density in the inner detector where time resolution is critical, and lower density in the outer detector where cost-effectiveness is prioritized. This localized optimization reduces overall manufacturing cost while maintaining detection probability through the combined system.
Solution Approach 2:
The outer detector uses cheaper, lower-density scintillators that serve as a complementary detection layer. While individually less efficient, these cost-effective components provide sufficient backup detection capability, allowing the system to reduce overall manufacturing cost while maintaining adequate detection probability.
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 configuration improves PET image quality by increasing the detection probability of gamma rays and reducing manufacturing costs, while the energy value adder and simultaneous counted information generator enhance the accuracy of image reconstruction.
Implementation Method 1
The PET detector is formed, for example, by arranging, in a ring, multiple detector modules including scintillators that convert gamma rays (including annihilation radiation) into visible light.
Implementation Method 2
Each detector module includes scintillators and photodetectors
Data Source
AI summary
In a PET device, a first detector includes a plurality of first scintillators and detects gamma rays emitted from positron-emitting radionuclides injected into a subject. A second detector is provided on the outer circumferential side of the first detector, includes a plurality of second scintillators arranged in an arrangement surface density lower than that of the first scintillators, and detects gamma rays that have passed through the first detector. A counted information acquiring unit acquires, as first counted information and second counted information, the detection positions, energy values, and detection time regarding gamma rays detected by the first detector and the second detector. Based on the detection time contained in each of the first counted information and the second counted information, an energy value adder generate corrected counted information by summing the energy values contained in the first counted information and the second counted information.