Scintillator Material Composition for Low Afterglow X-ray Detection

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Solution Overview

Problem

Conventional X-ray CT scanners face challenges with high-resolution imaging due to high afterglow levels in scintillators, which increase scan times and reduce image quality, particularly in GGAG:Ce materials used in X-ray detectors.

Innovation Solution

A fluorescent material with a specific composition, including Ce, Gd, Al, Ga, O, Fe, and Lu/Y, optimized to reduce afterglow intensity by controlling the content of Fe and other elements, ensuring a low afterglow level and high fluorescence intensity, is used as a scintillator in X-ray detectors.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the thickness of scintillator is increased to improve X-ray absorption, then X-ray absorption coefficient is improved, but light transmittance decreases and device complexity increases

Engineering Contradiction:
ImproveX-ray absorptionVSAvoidscintillator thickness
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent changes the chemical composition parameters of the scintillator material by incorporating specific ratios of Gd, Lu, Y, Ce, Al, Ga, and Fe to achieve optimal X-ray absorption with reduced thickness requirements

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent uses a composite scintillator material combining multiple elements (Gd, Lu, Y, Ce, Al, Ga, Fe) in specific proportions to achieve superior performance compared to single-element materials, enabling both high absorption and maintained transmittance

Inventive Principle:
Principle #40Composite materials

2Reliability

If GGAG:Ce scintillator is used to achieve high fluorescence intensity, then detection sensitivity is improved, but afterglow level increases and scan time increases

Engineering Contradiction:
Improvedetection sensitivityVSAvoidscan time
Core Design Contradiction:
ReliabilityVSLoss of time

Solution Approach 1:

The patent modifies the compositional parameters of the scintillator by adding Fe and adjusting the ratios of Gd, Lu, and Y to control the afterglow characteristics while maintaining fluorescence intensity

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent converts the potential harm of Fe (which can increase afterglow) into a benefit by precisely controlling its content at 0.003-0.01 mass%, where it actually helps reduce afterglow while maintaining fluorescence properties

Inventive Principle:
Principle #22Blessing in disguise (Convert harm into benefit)

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 results in a scintillator with reduced afterglow, enabling shorter scan times and improved image resolution in X-ray CT scanners, enhancing detection performance and stability.

Implementation Method 1

a fluorescent material configured to absorb radiation such as X-rays and emit fluorescence

Methodology Applied
Scientific EffectPhotoluminescence: Photoluminescence

Implementation Method 2

The scintillator is made of a fluorescent material such as a CdWO 4 single crystal, a (Y, Gd) 2 O 3 :Eu, Pr ceramic

Methodology Applied
Scientific EffectScintillation: Scintillation

Data Source

PatentEP2128222B1Fluorescent material, scintillator using the fluorescent material, and radiation detector
Publication Date: 2014.08.20 PROTERIAL LTD
  • EP2128222B1 patent drawingFigure 1~2
  • EP2128222B1 patent drawingFigure 3~4
  • EP2128222B1 patent drawingFigure 5~6

AI summary

A fluorescent material for a scintillator to be used in a radiation detector is provided. The fluorescent material is designed to have a high fluorescent intensity and a low level of afterglow a short term of 1 to 300 ms after the termination of X-ray radiation. The above fluorescent material contains Ce as an activator. In addition, the material must contain at least Gd, Al, Ga, O, Fe, and a component M. The component M is at least one of Mg, Ti, and Ni. In addition, the composition of the material must be expressed by the general formula:         (Gd1-x-zLuxCez)3+a(Al1-u-sGauScs)5-aO12 wherein 0≦a≦0.15, 0≦x≦0.5, 0.0003≦z≦0.0167, 0.2≦u≦0.6, and 0 ≦s≦0.1, and wherein, regarding the concentrations of Fe and M, Fe: 0.05 ≦Fe concentration (mass ppm)≦ 1, and 0≦M concentration (mass ppm)≦ 50.