Inorganic Scintillator for PET-MRI Magnetic Field Compatibility
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Solution Overview
Problem
Conventional PET apparatuses face limitations in imaging due to the use of photoelectric multipliers, which are incompatible with strong magnetic fields, and existing scintillators have long decay times and suboptimal light output, hindering accurate tumor infiltration diagnosis and high-resolution imaging.
Innovation Solution
An inorganic scintillator with a chemical composition of CexLnySizOu, where Ln represents Y, Gd, or Lu, emitting fluorescence with a peak wavelength between 450-600 nm for high photodiode conversion efficiency and featuring a monoclinic crystal structure with oxygen-hexacoordinated cerium, allowing for high light output and short decay times.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If photoelectric multipliers are used in PET apparatuses, then high conversion efficiency for 415 nm fluorescent light is achieved, but compatibility with strong magnetic fields is lost
Solution Approach 1:
The patent changes the wavelength parameter of the scintillator's fluorescent light from 415 nm to 450-600 nm to match the high conversion efficiency range of photodiodes, enabling magnetic field compatibility while maintaining measurement precision
Solution Approach 2:
The patent substitutes photoelectric multipliers with photodiodes, replacing a magnetic field-sensitive device with one that is magnetic field-compatible, while compensating for the wavelength mismatch through scintillator modification
2Measurement precision
If oxide fluorescent material with garnet crystal structure is used, then light intensity peak wavelength of 450-600 nm is achieved, but decay time becomes excessively long
Solution Approach 1:
The patent changes the crystal structure parameter from garnet to monoclinic system and adjusts the chemical composition to CexLnySizOu, which simultaneously achieves the desired 450-600 nm peak wavelength and reduces decay time to suitable levels for PET imaging
Solution Approach 2:
The patent creates a composite scintillator material combining specific rare earth elements (Y, Gd, Lu) with cerium and silicon in a monoclinic structure, achieving optimal balance between wavelength characteristics and decay time
3Productivity
If scintillator with short decay time is used, then examination time is reduced and pile-up is prevented, but light output and wavelength characteristics may be compromised
Solution Approach 1:
The patent optimizes the chemical composition parameters (x, y, z, u in CexLnymSizOu) and crystal structure to achieve a balanced performance where short decay time (improving productivity) is maintained alongside sufficient light output and appropriate wavelength characteristics (maintaining measurement precision)
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 scintillator enables high-resolution imaging by converting fluorescence to electrical signals with high efficiency, preventing 'pile-up' and allowing for simultaneous metabolic and anatomical imaging in PET-MRI systems, enhancing diagnostic precision and reducing examination time.
Implementation Method 1
an inorganic scintillator having a chemical composition represented by the following formula (1) and inequalities (2) to (5) and emitting fluorescence upon incidence of radiation
Implementation Method 2
Photodiodes, on the other hand, are elements capable of converting fluorescence emitted from a scintillator into an electrical signal without being affected by magnetic fields
Data Source
AI summary
The inorganic scintillator of the invention has the chemical composition represented by CexLnySizOu (where Ln represents at least two elements selected from among Y, Gd and Lu. 0.001≦x≦0.1, 1.9≦y≦2.1, 0.9≦z≦1.1, 4.9≦u≦5.1) and emits fluorescence upon incidence of radiation, wherein the maximum peak wavelength in the intensity spectrum of the emitted fluorescence is a peak in the range between 450 nm and 600 nm.