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Proceedings Paper

High-resolution amorphous silicon image sensor
Author(s): Thorsten Graeve; Youming Li; Andrew Fabans; Wingo Huang
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Paper Abstract

This paper describes a new prototype a-Si (amorphous silicon) x-ray image sensor developed at EG&G Reticon. The sensor consists of a 512 by 512 array of a-Si photodiodes placed on 100 micrometer centers. The active area measures 5 cm on a side. Each pixel is addressed by a pair of switching diodes rather than the more common TFT (thin film transistor) switch. This approach leads to a simplified all-diode design with excellent fill factor, large dynamic range and good performance. The sensor is intended primarily for high-resolution x-ray imaging applications. A scintillator in direct contact with the diode array is used to convert incident x-ray photons to visible light detectable by the a-Si photodiodes. Since the conversion takes place directly at the sensor surface, no bulky intermediate optics are needed. The entire sensor plus support electronics can be mounted in a package less than 3 cm thick. The paper describes the sensor performance in terms of dark current, image lag, sensitivity and dynamic range. The MTF of the sensor and attached scintillator is measured by exposing the device through a narrow slit illuminated by a 50 kV x-ray source. Good contrast and sensitivity are achieved even at the Nyquist limit of the sensor resolution. Several images demonstrating the resolution and sensitivity of the sensor are presented.

Paper Details

Date Published: 11 April 1996
PDF: 5 pages
Proc. SPIE 2708, Medical Imaging 1996: Physics of Medical Imaging, (11 April 1996); doi: 10.1117/12.237811
Show Author Affiliations
Thorsten Graeve, EG&G Reticon (United States)
Youming Li, EG&G Reticon (United States)
Andrew Fabans, EG&G Reticon (United States)
Wingo Huang, EG&G Reticon (United States)

Published in SPIE Proceedings Vol. 2708:
Medical Imaging 1996: Physics of Medical Imaging
Richard L. Van Metter; Jacob Beutel, Editor(s)

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