Novel nanocrystalline Gd sub(2O) sub(3)(Eu) scintillator screens with a micro-pixel structure for high spatial resolution X-ray imaging

• Published in: Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment Vol. 652; no. 1; pp. 717 - 720
• Main Authors: Cha, Bo Kyung, Lee, Seung Jun, Muralidharan, P, Kim, Do Kyung, Kim, Jong Yul, Cho, Gyuseong, Jeon, Sungchae, Huh, Young
• Format: Journal Article
• Language: English
• Published: 01-10-2011
• Subjects: Charge coupled devices; Imaging; Nanocrystals; Pixels; Screens; Silicon; Spatial resolution; X-rays
• ISSN: 0168-9002
• DOI: 10.1016/j.nima.2011.01.024

We developed a novel pixel-structured scintillation screen with nanocrystalline Gd sub(2O) sub(3):Eu particle sizes for high spatial resolution X-ray imaging detectors. Nanocrystalline Gd sub(2O) sub(3):Eu scintillators were successfully synthesized with a hydrothermal method and a subsequent calcination treatment, which were used as a material for converting incident X-rays into visible light. In this work, silicon-based pixel structures with different 100, 50 and 30 mu m pixel sizes, a 10 mu m wall width and a 120 mu m thickness were prepared with the standard photolithography and the deep reactive ion etching (DRIE) process. Subsequently, a micro-pixel-structured scintillation screen was fabricated by adding the synthesized nanocrystalline Gd sub(2O) sub(3):Eu scintillating phosphor to pixel-structured silicon arrays. Additionally, X-ray imaging performance such as relative light intensity, X-ray to light response and the spatial resolution in terms of modulation transfer function (MTF) were measured by using an X-ray source and a lens-coupled charge coupled device (CCD) camera system. The light intensity of the pixel-structured nanocrystalline Gd sub(2O) sub(3):Eu screen was much higher than that of a pixel-structured sample made with a commercial microcrystalline Gd sub(2O) sub(3):Eu product due to the density of the nanocrystalline Gd sub(2O) sub(3):Eu scintillating powder-filled silicon structure. As the pixel size of the pixel-structured silicon decreased, the light intensity decreased. However, as the pixel size decreased, the spatial resolution significantly improved with no evident crosstalk from the emitted optical photons between adjacent scintillating pixels. The MTF of pixel-structured nanocrystalline Gd sub(2O) sub(3):Eu screens with a 100 and a 50 mu m pixel size was 20% and 30% at 6 lp/mm, respectively. As a result, this new technology showed that a microchannel structure based on a nanocrystalline Gd sub(2O) sub(3):Eu scintillator could provide higher light intensity and high spatial resolution imaging compared to conventional microcrystalline scintillating phosphor.