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Proceedings Paper

New CsI:Na-selenium x-ray detector
Author(s): Dae Woo Seok; Jang Yong Choi; Sang Sik Kang; Gi Won Jang; Chi Woong Mun; Sang Hee Nam
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Paper Abstract

Digital x-ray imager known to flat-panel detector has been studied for the application of a various medical modalities. Currently, two types of detection methods have been realized in digital radiography. One is an indirect conversion method and the other is a direct conversion method. we have been developing a new x-ray detector that combines a columnar CsI:Na scintillation layer with a photosensitive a-Se with dielectric thin film. In this structure, an x-ray is converted to visible light in a CsI:Na scintillation layer and visible light is then converted to electric charges in a-Se layer. The electron-hole pairs can be also generated from x-ray interaction in the a-Se photoconductor, which can improve the detection efficiency of electric charge. We designed the thickness of CsI:Na scintillator by using computer simulation. MCNP is a general-purpose, continuous-energy, generalized-geometry, time-dependent, coupled neutron / photon / electron Monte Carlo transport code. The spectra of x-ray absorption was simulated by using MCNP 4C code. The morphology of the vacuum deposited CsI:Na scintillator and the parylene film were analyzed. Photoluminescence characterization of CsI:Na showed a light emission peak centered at 420nm as expected, which matched the absorption spectrum of amorphous selenium(a-Se). For an electric field of 10V/μm, the dark currents of our detector were below 370 pA/cm2 and the SNR of CsI:Na coupled a-Se detector with a dielectric layer was 1.8 times greater than that without CsI:Na layer.

Paper Details

Date Published: 6 May 2004
PDF: 6 pages
Proc. SPIE 5368, Medical Imaging 2004: Physics of Medical Imaging, (6 May 2004); doi: 10.1117/12.536200
Show Author Affiliations
Dae Woo Seok, Inje Univ. (South Korea)
Jang Yong Choi, Inje Univ. (South Korea)
Sang Sik Kang, Inje Univ. (South Korea)
Gi Won Jang, Inje Univ. (South Korea)
Chi Woong Mun, Inje Univ. (South Korea)
Sang Hee Nam, Inje Univ. (South Korea)

Published in SPIE Proceedings Vol. 5368:
Medical Imaging 2004: Physics of Medical Imaging
Martin J. Yaffe; Michael J. Flynn, Editor(s)

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