Radiation Imaging Panel Protective Layer Light Diffusion Control
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Solution Overview
Problem
The existing radiation imaging panels face challenges in maintaining Modulation Transfer Function (MTF) due to excessive light diffusion caused by high or low light reflectance in the phosphor protecting layer, leading to degradation in image quality.
Innovation Solution
A radiation imaging panel design featuring a protective layer with a first resin layer containing metal compound particles for controlled light reflection and a second resin layer with higher absorptance, optimizing light reflectance and absorptance to prevent light diffusion and enhance MTF.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the light reflectance of the phosphor protecting layer is increased to improve light reflection efficiency, then more light can be reflected back to the photoelectric conversion element, but light diffusion increases causing MTF degradation
Solution Approach 1:
The phosphor protecting layer is divided into multiple layers with different light reflectance characteristics. The first phosphor protecting layer has high light reflectance to reflect light back to the photoelectric conversion element, while the second phosphor protecting layer has low light reflectance to minimize light diffusion. This segmentation allows each layer to perform its specific function without causing MTF degradation.
Solution Approach 2:
Different regions of the phosphor protecting layer structure are assigned different light reflectance properties. The layer adjacent to the scintillator is designed with high reflectance to maximize light return, while the outer layer is designed with low reflectance to prevent excessive diffusion. This local differentiation of optical properties resolves the contradiction between reflection efficiency and image quality.
2Measurement precision
If the light reflectance of the phosphor protecting layer is decreased to reduce light diffusion, then MTF can be maintained, but less light is reflected back reducing detection efficiency
Solution Approach 1:
The phosphor protecting layer is segmented into multiple functional layers. The first layer provides high light reflectance to ensure sufficient light returns to the photoelectric conversion element for efficient detection, while the second layer provides low light reflectance to minimize diffusion and maintain MTF. This segmentation enables both high detection efficiency and good image quality.
Solution Approach 2:
The phosphor protecting layer is constructed as a composite structure with multiple layers having different optical properties. By combining materials or structures with high reflectance characteristics in the inner layer and low reflectance characteristics in the outer layer, the system achieves both high light reflection efficiency for detection and low light diffusion for maintaining MTF.
3Use of energy by moving object
If a single-layer phosphor protecting layer with high light reflectance is used to maximize light return, then detection efficiency improves, but light diffusion causes MTF degradation
Solution Approach 1:
The single-layer high reflectance structure is segmented into multiple layers with different reflectance characteristics. The inner layer maintains high reflectance for efficient light return to the photoelectric conversion element, while the outer layer has reduced reflectance to minimize light diffusion. This segmentation resolves the contradiction present in single-layer designs.
Solution Approach 2:
The solution moves from a single-dimensional (single-layer) approach to a multi-dimensional (multi-layer) approach. By adding the layer dimension with different optical properties at different depths, the system can simultaneously achieve high light return efficiency from the inner layer and low light diffusion from the outer layer, thereby maintaining both detection efficiency and MTF.
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 optimized light reflectance and absorptance in the protective layer improve MTF by reducing light diffusion, resulting in enhanced image quality and sensitivity while preventing moisture damage to the scintillator.
Implementation Method 1
a light reflectance r1 [%] of the first resin layer satisfies 47% ≤ r1 < 75%
Implementation Method 2
a light absorptance a2 [%] of the second resin layer satisfies 20% ≤ a2 ≤ 80%
Implementation Method 3
a scintillator containing a plurality of columnar crystals arranged on the substrate
Implementation Method 4
an average particle diameter d1 of the particles contained in the first resin layer is a particle diameter which causes Rayleigh scatting of light
Implementation Method 5
an average particle diameter d2 of the particles contained in the second resin layer is a particle diameter which causes Mie scatting of the light
Data Source
AI summary
A radiation imaging panel comprising a substrate in which a plurality of pixels each including a photoelectric conversion element are arranged, a scintillator containing a plurality of columnar crystals arranged on the substrate, and a protective layer is provided. The protective layer includes a first resin layer arranged so as to cover the scintillator and a second resin layer arranged on the first resin layer, and the first resin layer contains a resin to which particles of a metal compound is added. A light reflectance r1 [%] of the first resin layer satisfies 47%<r1<75%, and a light reflectance r2 [%] of the second resin layer and a light absorptance a2 [%] of the second resin layer satisfy r2<a2.