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Apr. 21, 2020
Toray Industries, Inc.
New Toray Technology Enhances the Brightness of
X-Ray Scintillator Panels Enabling Reduction of
Radiation Doses to Boost Patient Care

Tokyo, Japan, April 21, 2020 – Toray Industries, Inc., announced today that it has developed a wavelength conversion technology using phosphors that enhance the brightness of X-ray scintillator panels 1 by roughly 30%. This technology can more clearly discern lung diseases and the other illnesses while reducing radiation doses in medical X-ray system. The company will commercialize this technology soon. Medical X-ray system detectors are generally comprised of scintillator panels that convert X-rays to visible light, and photosensor panels that then convert this light into digital images. Scintillator panels have a phosphor layer with several hundred microns of thickness that absorb X-rays and emit light. The phosphor layer is composed of CsI 2 or GOS3. Unlike CsI, GOS does not need long-time deposition process, thus making the manufacturing processes simple and low-cost. GOS is also very stable and durable under X-ray conditions, but the issue has consistently been that GOS is less bright than CsI. For many years, Toray has been developing the wavelength conversion technology necessary for display materials. By improving and innovating this technology, we can now enhance the brightness of the GOS scintillator panel. The key to this technology is our unique compounding technique that mixes in a "second phosphor".The second phosphor allows absorption of short wavelength light between 350 to roughly 400 nanometers, in which the photosensor has low sensitivity in the emission spectrum of GOS, to be converted to long wavelength light nearly 550 nanometers, in which the photosensor has high sensitivity. Using this technology, the phosphor layer "GOS-α" keeps the advantages of GOS (such as low-cost, high stability, and high durability GOS) while enhancing the brightness by about 30% over conventional scintillator panels of similar thickness. Toray has been mass-producing X-ray scintillator panels using regular GOS for general medical radiographic applications since 2016. Toray aims to further expand the X-ray scintillator panel business with products adopting the new "GOS-α" phosphor layer, by significantly increasing the range of applications and uses that panels currently offer. Additionally, new technology will be combined with a pixelated scintillator4 by applying Toray's proprietary technology to enable image sharpening. Toray will keep striving to develop revolutionary materials that transform societies in keeping with its commitment to innovative ideas, technologies, and products that deliver valuable results.

X-ray scintillator panel using Toray's new technology (left) and diagram of light wavelength conversion (right)
Glossary
1. X-ray scintillator panel
A component of an X-ray imaging device. This panel contains phosphor materials that are excited by radiation (such as X-rays) and emits fluorescence. GOS and CsI are the two main phosphor materials being commonly used as scintillators.
2. CsI
Thallium doped Cesium iodide. CsI scintillator transmits light well, so that the scintillator panel has high brightness. However, it is expensive because of the vacuum deposition cost and the moisture-proof sealing cost to prevent deterioration by moisture.
3. GOS
Terbium doped Gadolinium oxysulfide. The GOS scintillator has a simple structure and can be manufactured at a low cost. It is also very stable and durable under X-rays, but is less bright than CsI.
4. Pixelated scintillator
Scintillator panel with barrier ribs designed to be aligned with the pixels of the photosensor. Phosphor materials are filled in the cells that are separated by barrier ribs. Barrier ribs prevent the light emitted by the phosphors from diffusing into the next cell so that very sharp X-ray images can be obtained.