Browse Prior Art Database

NEW CLASS OF GARNETS AS PHOSPHOR AND SCINTILLATOR MATERIALS

IP.com Disclosure Number: IPCOM000237927D
Publication Date: 2014-Jul-22
Document File: 6 page(s) / 249K

Publishing Venue

The IP.com Prior Art Database

Abstract

The invention proposes a Cerium doped rare earth garnet with improved gamma ray stopping power compared to conventional rare earth garnets. The garnet has a potential to be used as a scintillator material for positron emission tomography (PET). The material consists of cerium doped Ca2LuHf2Al3O12.

This text was extracted from a Microsoft Word document.
At least one non-text object (such as an image or picture) has been suppressed.
This is the abbreviated version, containing approximately 53% of the total text.

NEW CLASS OF GARNETS AS PHOSPHOR AND SCINTILLATOR MATERIALS

BRIEF ABSTRACT

The invention proposes a Cerium doped rare earth garnet with improved gamma ray stopping power compared to conventional rare earth garnets. The garnet has a potential to be used as a scintillator material for positron emission tomography (PET). The material consists of cerium doped Ca2LuHf2Al3O12.

KEYWORDS

Garnet, cerium doped, scintillator, PET, low crystal growth, gamma ray stopping

 

BACKGROUND

There are two materials used as scintillators in positron emission tomography (PET). The materials include Bi4Ge3O12 (BGO) and Lu2SiO5:Ce (LSO). BGO is relatively inexpensive and has excellent gamma ray stopping power, but suffers from low fluorescent efficiency which is typically 9000 photons/MeV and a relatively slow decay speed of 300 ns. LSO is more efficient with fluorescent efficiency of 29,000 photons / MeV and has much faster decay speed of 40 ns. However LSO is very expensive both in terms of raw material (lutetium) and crystal growth costs.

Generally, cerium doped garnets are useful phosphors. High density cerium doped rare earth garnets are used as scintillator materials.

There are several attempts known in the art in growing single crystals of LuPO4 doped with cerium. However, single crystals of LuPO4 doped with cerium include second phase impurities.

A conventional technique includes formation of BaHfO3-Ce and SrHfO3-Ce transparent ceramics. However, optical quality of such crystals is not good enough for PET scintillators due to volatility of Ba and Sr and due to second phase impurities.

Therefore, there is a need for a garnet composition which is economical and used as scintillator material for PET system.

DETAILED DESCRIPTION

Generally, oxide garnets consist of a compound made from metal oxides with eight metal atoms in three different size sites, three large metal atoms in dodecahedral sites, two medium sized metal atoms in octahedral sites and three small metal atoms in tetrahedral sites. There are also 12 oxygen atoms. All the metal ions are either of +3 valence or +2 valance ions charge compensated by use of +4 valence ions. The present invention includes a kimzeyite type garnet phosphor with modified composition of Ca3Hf2Al2SiO12. Modification in composition is achieved by replacing one of the dodecahedral Ca atoms with a rare earth ion and charge compensation by repla...