Advanced a-Se film with high sensitivity and heat resistance for x-ray detectors

Koichi Ogusu; Osamu Nakane; Yasunori Igasaki; Yoshinori Okamura; Satoshi Yamada; Tadaaki Hirai

doi:10.1117/12.811496

13 March 2009 Advanced a-Se film with high sensitivity and heat resistance for x-ray detectors

Koichi Ogusu, Osamu Nakane, Yasunori Igasaki, Yoshinori Okamura, Satoshi Yamada, Tadaaki Hirai

Proceedings Volume 7258, Medical Imaging 2009: Physics of Medical Imaging; 72583M (2009) https://doi.org/10.1117/12.811496
Event: SPIE Medical Imaging, 2009, Lake Buena Vista (Orlando Area), Florida, United States

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.

Citation Download Citation

Koichi Ogusu, Osamu Nakane, Yasunori Igasaki, Yoshinori Okamura, Satoshi Yamada, and Tadaaki Hirai "Advanced a-Se film with high sensitivity and heat resistance for x-ray detectors", Proc. SPIE 7258, Medical Imaging 2009: Physics of Medical Imaging, 72583M (13 March 2009); https://doi.org/10.1117/12.811496

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