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Proceedings Paper

Advanced a-Se film with high sensitivity and heat resistance for x-ray detectors
Author(s): Koichi Ogusu; Osamu Nakane; Yasunori Igasaki; Yoshinori Okamura; Satoshi Yamada; Tadaaki Hirai
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Paper Abstract

Amorphous selenium (a-Se) is well known to provide superior spatial resolution and low dark current when used as a direct conversion X-ray photoconductor in flat panel detectors (FPD). However, a-Se properties are also known to fluctuate at higher environmental temperatures, so the temperature has to be carefully controlled. To overcome this problem we developed a newly modified a-Se photoconductor with electrical and X-ray characteristics that remain constant at temperatures up to 70 degrees C. On the other hand, in terms of a-Se dark current levels, the higher the electrical field, the higher the dark current level. For this reason, conventional a-Se photoconductors are used at a comparatively low electric field of 10 V/μm. We also investigated the electrical characteristics of film compositions containing a-Se that provide high gain and low dark current. Experiments were made with sandwich cells and then with CMOS (50 μm pixel pitch) readout panels. Our new a-Se photoconductor operated at 40 V/μm delivers sensitivity 3 to 4 times higher than the conventional a-Se operated at 10 V/μm, while keeping the dark current density at 5 pA/mm2. This a-Se photoconductor will prove effective for low-dose X-ray imaging including mammography and tomosynthesis.

Paper Details

Date Published: 13 March 2009
PDF: 10 pages
Proc. SPIE 7258, Medical Imaging 2009: Physics of Medical Imaging, 72583M (13 March 2009); doi: 10.1117/12.811496
Show Author Affiliations
Koichi Ogusu, Hamamatsu Photonics K.K. (Japan)
Osamu Nakane, Hamamatsu Photonics K.K. (Japan)
Yasunori Igasaki, Hamamatsu Photonics K.K. (Japan)
Yoshinori Okamura, Hamamatsu Photonics K.K. (Japan)
Satoshi Yamada, Hamamatsu Photonics K.K. (Japan)
Tadaaki Hirai, Hamamatsu Photonics K.K. (Japan)

Published in SPIE Proceedings Vol. 7258:
Medical Imaging 2009: Physics of Medical Imaging
Ehsan Samei; Jiang Hsieh, Editor(s)

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