Scintillator Plate Additive Gradient for Light Transfer
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Solution Overview
Problem
Existing scintillator technologies face challenges in improving resolution and luminance characteristics, particularly in radiation imaging applications, where the efficiency of light transfer from needle-like crystals to light-receiving elements is hindered by gaps and refractive index differences, leading to suboptimal performance.
Innovation Solution
A scintillator plate with needle-like crystals made from an alkali metal halide compound, incorporating thallium iodide as an activator agent and copper or silver as additive elements, is developed. The additive elements are concentrated higher on one surface than the other, with controlled vapor deposition techniques to manage crystal thickness and temperature, ensuring efficient light transfer and minimizing light attenuation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If needle-like crystal groups are used to efficiently transfer light to light-receiving elements, then light transfer efficiency is improved, but resolution characteristics deteriorate due to gaps and total reflection between crystals
Solution Approach 1:
The patent applies local quality by creating a concentration gradient of additive elements within the scintillator crystal structure. The additive elements are concentrated at specific regions (surfaces or interfaces) rather than uniformly distributed, which locally modifies optical properties to reduce reflection at crystal boundaries while maintaining the needle-like structure for light guidance. This resolves the contradiction by improving light transfer efficiency at crystal interfaces without compromising the resolution-providing gap structure.
Solution Approach 2:
The patent changes physical parameters by controlling the concentration and distribution of additive elements (such as copper or silver) within the cesium iodide crystal lattice. By adjusting the concentration gradient and spatial distribution of these additives, the refractive index and light reflection characteristics are modified, enabling efficient light transfer through the needle-like crystals while maintaining resolution characteristics through controlled gap formation.
2Measurement precision
If vapor deposition is used to form thin needle-like crystals, then resolution characteristics are improved, but manufacturing complexity increases due to precise substrate positioning requirements
Solution Approach 1:
The patent simplifies the vapor deposition process by changing the substrate temperature parameter during deposition. By controlling the substrate temperature within a specific range, the patent achieves formation of needle-like crystals with good resolution characteristics without requiring precise oblique positioning of the substrate. This parameter change reduces manufacturing complexity while maintaining resolution improvements.
3Illumination intensity
If multiple activator agents with different melting points are used, then emission luminance is improved, but manufacturing precision requirements increase
Solution Approach 1:
The patent uses composite materials by combining cesium iodide base material with multiple activator agents (such as thallium iodide) and additive elements (copper or silver). This composite structure enables improved emission luminance through the synergistic effects of different activators while the vapor deposition process with controlled temperature parameters simplifies the manufacturing precision requirements compared to solid-state mixing methods.
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 solution enhances the resolving power and luminance characteristics of the scintillator, allowing for improved light guidance to the sensor panel while maintaining the structural integrity of the needle-like crystals, thus addressing the limitations of existing technologies.
Implementation Method 1
an indirect conversion FPD that converts radiation transmitted through an object into light by a scintillator
Implementation Method 2
A needle-like crystal group of an alkali metal halide compound such as cesium iodide is widely used for a scintillator that converts radiation into light to efficiently transfer emitted light to a light-receiving element. A needle-like crystal group has gaps formed between the respective needle-like crystals and repeats total reflection of light in the crystals due to the difference in refractive index between the crystals and air, thereby effectively guiding the emitted light to the light-receiving element.
Implementation Method 3
PTL 1 discloses that when a scintillator is formed by vapor deposition, a substrate is placed above a vapor deposition source of a scintillator material in the vertical direction obliquely with respect to the vertical axis to form thin needle-like crystals
Data Source
AI summary
A scintillator plate provided with a scintillator having, on a substrate, a first surface facing the substrate and a second surface on an opposite side to the first surface is provided. The scintillator includes needle-like crystals each containing an alkali metal halide compound, thallium iodide, and copper and/or silver as an additive element. The additive element is contained in the second surface at a concentration of not less than 0.04 mol % and not more than 0.5 mol %, and has a higher concentration in the first surface than in the second surface. A thickness of a largest portion of each of the needle-like crystals becomes not less than one time and not more than nine times a thickness at a height of 10 μm in a direction from the first surface to the second surface.