Garnet Direct Conversion Radiation Detector

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Solution Overview

Problem

Indirect detection methods using scintillators for X-ray and gamma-ray detection suffer from energy loss and limited energy resolution due to the conversion of radiation to light and then to electrons, whereas direct conversion methods with materials like CdTe or CZT are expensive and difficult to modify for different detector systems.

Innovation Solution

A direct conversion radiation detector utilizing a garnet material with a composition of Z3(AlxGay)5O12:Ce, where Z is Lu, Gd, Y, or Tb, and y is greater than or equal to x, which allows for direct conversion of radiation into electron-hole pairs without the need for additional light conversion, and includes a pixelated electrode and integrated circuit for processing electronic signals.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If indirect detection method using scintillators is used, then radiation detection is achieved, but energy resolution is limited due to energy loss in conversion steps

Engineering Contradiction:

Improveenergy resolutionVSAvoidenergy loss in conversion

Core Design Contradiction:

Measurement precisionVSLoss of energy

Solution Approach 1:

The patent extracts and removes the scintillator layer from the detector structure, transitioning from indirect detection (radiation→light→electrons) to direct detection (radiation→electrons). This eliminates the intermediate light conversion step that causes energy loss and limits energy resolution, allowing direct measurement of radiation energy with much higher precision.

Inventive Principle:

Principle #2Taking out (Extraction)

2Measurement precision

If direct conversion materials like CdTe or CZT are used, then energy resolution is improved, but manufacturing cost and difficulty increase

Engineering Contradiction:

Improveenergy resolutionVSAvoidmanufacturing difficulty

Core Design Contradiction:

Measurement precisionVSEase of manufacture

Solution Approach 1:

The patent changes the material parameter from conventional direct conversion materials (CdTe, CZT) to perovskite materials. Perovskites offer similar or superior direct conversion capabilities with much easier fabrication processes, solution-based deposition methods, and lower material costs, while maintaining the desired energy resolution performance.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent adopts perovskite materials that can be manufactured using low-cost solution processing techniques rather than expensive vacuum deposition or crystal growth methods required for CdTe and CZT. This dramatically reduces manufacturing cost and complexity while achieving comparable performance.

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

3Use of energy by moving object

If single crystal garnet materials are used for direct conversion, then conversion efficiency is improved, but production cost and difficulty increase significantly

Engineering Contradiction:

Improveconversion efficiencyVSAvoidproduction difficulty

Core Design Contradiction:

Use of energy by moving objectVSEase of manufacture

Solution Approach 1:

The patent employs composite perovskite structures that can be fabricated as thin films or polycrystalline layers rather than requiring single crystals. These composite forms maintain efficient radiation-to-electron conversion while being manufacturable using standard thin-film deposition techniques, eliminating the need for expensive and complex single crystal growth processes.

Inventive Principle:

Principle #40Composite materials

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 approach provides improved energy resolution and cost-effectiveness by using garnets as direct conversion materials, enabling better image quality and flexibility in tuning properties for various detector systems, while minimizing recombination and luminescence losses.

Implementation Method 1

A direct conversion radiation detector utilizes a garnet material with a composition of Z3(AlxGay)5O12:Ce... which allows for direct conversion of radiation into electron-hole pairs

Methodology Applied

Scientific EffectPhotoelectric effect: Photoelectric Effect

Data Source

PatentUS9958556B1Direct conversion radiation detector

Publication Date: 2018.05.01 KONINKLIJKE PHILIPS NV

AI summary

The present invention relates to a direct conversion radiation detector for wherein the direct conversion material comprises a garnet with a composition of Z3(AlxGay)O12:Ce, wherein Z is Lu, Gd, Y, Tb or combinations thereof and wherein y is equal to or greater than x; and preferably Z comprises Gd. Suitable garnets directly convert radiation, such as x-rays or gamma-rays, into electronic signals. Preferably photoluminescence of the garnet is low or absent. The detector is particularly suitable for use in x-ray imaging devices, such as computed tomography. In some embodiments photoluminescence of garnets might be used to construct a hybrid direct-indirect conversion detector, which may be particularly suitable for use with Time-of-Flight PET.