Phosphor Layer Particle Gradients for X-Ray Detector Sensitivity
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Solution Overview
Problem
Indirect conversion type radiation image detection devices face challenges in improving sensitivity and sharpness while maintaining manufacturing costs, as increasing the thickness of the wavelength converting layer or the size of phosphor particles leads to reduced image sharpness due to light scattering and spreading.
Innovation Solution
A single phosphor layer with first and second phosphor particles of different average diameters dispersed in a binder, where the weight of the first phosphor particles decreases with distance from the solid state detector, and a light reflective layer is used to enhance image detection, preventing the increase in manufacturing costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the thickness of the wavelength converting layer is increased to improve sensitivity, then the sensitivity is improved, but the image sharpness is reduced due to light scattering and spreading
Solution Approach 1:
The patent applies local quality by using phosphor particles of different sizes in different regions of the wavelength converting layer. Larger phosphor particles are placed in regions where higher light emission is needed for sensitivity, while smaller phosphor particles are placed in regions where light scattering should be minimized to maintain image sharpness. This spatial differentiation of particle characteristics allows simultaneous optimization of both sensitivity and sharpness.
Solution Approach 2:
The patent employs composite materials by combining phosphor particles of different sizes (first phosphor particles with larger average diameter and second phosphor particles with smaller average diameter) within the same wavelength converting layer. This composite structure enables the layer to exhibit both high light emission capability (from larger particles) and reduced light scattering (from smaller particles), resolving the contradiction between sensitivity and image sharpness.
2Reliability
If the size of phosphor particles is increased to improve sensitivity, then the light emission amount is increased, but the image sharpness is reduced due to light spreading
Solution Approach 1:
The patent applies local quality by using phosphor particles of different sizes in different regions of the wavelength converting layer. Larger phosphor particles are placed in regions where higher light emission is needed for sensitivity, while smaller phosphor particles are placed in regions where light scattering should be minimized to maintain image sharpness. This spatial differentiation of particle characteristics allows simultaneous optimization of both sensitivity and sharpness.
Solution Approach 2:
The patent employs composite materials by combining phosphor particles of different sizes (first phosphor particles with larger average diameter and second phosphor particles with smaller average diameter) within the same wavelength converting layer. This composite structure enables the layer to exhibit both high light emission capability (from larger particles) and reduced light scattering (from smaller particles), resolving the contradiction between sensitivity and image sharpness.
3Reliability
If a two-layer phosphor structure is used to improve sensitivity and sharpness, then both sensitivity and sharpness are improved, but the manufacturing cost increases
Solution Approach 1:
The patent merges the functions of multiple phosphor layers into a single wavelength converting layer by incorporating phosphor particles of different sizes within the same layer structure. This unified approach maintains the performance benefits of multi-layer structures (improved sensitivity and sharpness) while simplifying the manufacturing process and reducing costs associated with assembling multiple separate layers.
Solution Approach 2:
The patent employs composite materials by combining phosphor particles of different sizes (first phosphor particles with larger average diameter and second phosphor particles with smaller average diameter) within the same wavelength converting layer. This composite structure enables the layer to exhibit both high light emission capability (from larger particles) and reduced light scattering (from smaller particles), resolving the contradiction between sensitivity and image sharpness.
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 sensitivity and sharpness by optimizing the distribution of phosphor particles and using a light reflective layer, resulting in better image quality without increasing manufacturing costs.
Implementation Method 1
The wavelength converting layer contains phosphor for converting the radiation into the light
Implementation Method 2
a light reflective layer is used to enhance image detection
Data Source
AI summary
A radiation imaging system comprises a radiation source and a radiation image detection device. The radiation image detection device has a solid state detector and a wavelength converting layer arranged in this order from a radiation-incident side. The wavelength converting layer detects radiation passed through the solid state detector and converts the radiation into visible light. The solid state detector detects the visible light and produces image data. The wavelength converting layer is a phosphor layer, being a single layer, in which at least first phosphor particles having a first average particle diameter and second phosphor particles having a second average particle diameter are dispersed in a binder. The second average particle diameter is smaller than the first average particle diameter. The weight of the first phosphor particles per unit thickness of the wavelength converting layer decreases with increasing distance from the solid state detector.