Characterization of $Gd_2O_2S:Tb$ scintillator screen with pixelated silicon substrate for digital X-ray imaging application디지털 X선 영상을 위한 픽셀화 된 실리콘 기반의 $Gd_2O_2S:Tb$ 섬광체 스크린의 특성연구

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X-ray imaging detector in combination with scintillator screens have been widely used in digital X-ray imaging applications. The degradation of spatial resolution by light diffusion in scintillator layer can be overcome by pixelation. In this research, terbium doped gadolinium oxysulfide ($Gd_2O_2S:Tb$) was used as scintillation material for pixelated scintillator screen based on silicon substrates with micropore array of various dimensions fabricated using the photolithography and deep reactive ion etching (DRIE) process. The relative light output and the modulation transfer function (MTF) of each fabricated scintillator screen were measured by a cooled CCD for analysis of the effect of pixelated silicon substrate and optimization of micropore geometry in pixelated scintillator screen. The light transport simulation in pixelated scintillator geometry is conducted using MCNPX and LightTools simulation code. The simulation result is well matched with measurement results when compared of the measurement and simulation results. As the results, higher spatial resolution was obtained for smaller micropore pitch. The light output of the pixelated scintillator screens with equivalent fill factor decreases as the micropore pitch size decreases or the micropore thickness increases. This is most likely due to the light absorption in silicon wall surfaces. Therefore, further treatment of the wall surface, such as SiO2 reflective coating, seems necessary to compensate the reduction of the light generated. Then, the micropore thickness can be optimized to maximize the light output. The $Gd_2O_2S:Tb$ pixelated scintillator screen that has optimized micropore geometry could be applied to digital X-ray imaging.
Advisors
Cho, Gyu-Seongresearcher조규성researcher
Description
한국과학기술원 : 원자력및양자공학과,
Publisher
한국과학기술원
Issue Date
2010
Identifier
419185/325007  / 020083136
Language
eng
Description

학위논문(석사) - 한국과학기술원 : 원자력및양자공학과, 2010.2, [ vii, 43 p. ]

Keywords

Silicon substrate; Pixelated scintillator screen; Spatial resolution; 디지털 X선 영상; 공간분해능; 실리콘 기판; 픽셀형 섬광체 스크린; Digital X-ray imaging

URI
http://hdl.handle.net/10203/49567
Link
http://library.kaist.ac.kr/search/detail/view.do?bibCtrlNo=419185&flag=dissertation
Appears in Collection
NE-Theses_Master(석사논문)
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