Composite Scintillator with Large Stokes Shift Ligands
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Solution Overview
Problem
Current scintillators used in Time of Flight-PET (TOF-PET) systems suffer from limited spatial resolution due to high re-absorption of scintillation pulses, leading to poor image reconstruction and diagnostic accuracy, as they lack the necessary versatility to control and modulate their physicochemical characteristics for high quantum efficiency and short decay times.
Innovation Solution
A composite scintillator with specific electronic structures of two fluorescent ligands in metal-organic nanocrystals, which induce a large Stokes shift and ultrafast non-radiative energy transfer mechanisms, reducing re-absorption and enabling fast time response without compromising scintillation efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional scintillators are used to detect gamma photons in TOF-PET systems, then the system can operate with standard equipment, but the spatial resolution is limited to centimetre scale due to high re-absorption and long decay times
Solution Approach 1:
The patent modifies the molecular structure of scintillator compounds by introducing specific fluorophores with optimized electronic structures. This changes key parameters including decay time (reduced to sub-100ps range), Stokes shift (increased to reduce re-absorption), and quantum efficiency (enhanced through molecular design), enabling millimetre-scale spatial resolution in TOF-PET imaging
Solution Approach 2:
The invention creates composite scintillator materials combining organic fluorophores with specific host matrices. This composite approach allows simultaneous optimization of multiple properties: the fluorophore provides fast decay and large Stokes shift, while the host matrix ensures high quantum efficiency and appropriate mechanical properties, resolving the contradiction between speed and efficiency
2Use of energy by moving object
If scintillators with high quantum efficiency are used, then scintillation efficiency is improved, but re-absorption of scintillation pulses increases leading to lower detected photon density and slower system response
Solution Approach 1:
The patent optimizes the Stokes shift parameter by selecting fluorophores with specific HOMO-LUMO energy gaps. This parameter change increases the energy difference between absorption and emission bands, reducing spectral overlap and minimizing re-absorption. Simultaneously, the quantum efficiency is enhanced through molecular structure optimization, achieving both high efficiency and fast response
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
The composite scintillator achieves high scintillation efficiency and improved time resolution, enhancing the spatial resolution of TOF-PET images to the order of a millimeter, reducing the need for complex reconstruction algorithms and shorter acquisition times.
Implementation Method 1
A composite scintillator with specific electronic structures of two fluorescent ligands in metal-organic nanocrystals, which induce a large Stokes shift and ultrafast non-radiative energy transfer mechanisms
Implementation Method 2
Current scintillators used in Time of Flight-PET (TOF-PET) systems suffer from limited spatial resolution due to high re-absorption of scintillation pulses
Data Source
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AI summary
A fast and low re-absorption composite scintillator for detecting high-energy particles and/or electromagnetic radiation, comprising a matrix charged with metal-organic nanocrystals containing at least a metal and at least two fluorescent ligands, wherein the two ligands have respective absorption and emission bands defining a large Stokes shift and are arranged at an intermolecular distance from each other equal or shorter than 15 angstroms. The scintillator of the present invention thus makes it possible to minimise the scintillation light re-absorption effects resulting in increased scintillation efficiency and activate ultrafast non-radiative energy trans fer mechanisms resulting in improved response times on the detected signals.