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Proceedings Paper

Mercuric iodide medical imagers for low-exposure radiography and fluoroscopy
Author(s): George Zentai; Larry Partain; Raisa Pavlyuchkova; Cesar Proano; Barry N. Breen; A. Taieb; Ofer Dagan; Michael Schieber; Haim Gilboa; Jerry Thomas
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Paper Abstract

Photoconductive polycrystalline mercuric iodide deposited on flat panel thin film transistor (TFT) arrays is being developed for direct digital X-ray detectors that can perform both radiographic and fluoroscopic medical imaging. The mercuric iodide is either vacuum deposited by Physical Vapor Deposition (PVD) or coated onto the array by a wet Particle-In-Binder (PIB) process. The PVD deposition technology has been scaled up to the 20 cm x 25 cm size required in common medical imaging applications. A TFT array with a pixel pitch of 127 microns is used for these imagers. Arrays of 10 cm x 10 cm size have been used to evaluate performance of mercuric iodide imagers. Radiographic and fluoroscopic images of diagnostic quality at up to 15 pulses per second were demonstrated. As we previously reported, the resolution is limited to the TFT array Nyquist frequency of ~3.9 lp/mm (127 micron pixel pitch). Detective Quantum Efficiency (DQE) has been measured as a function of spatial frequency for these imagers. The DQE is lower than the theoretically calculated value due to some additional noise sources of the electronics and the array. We will retest the DQE after eliminating these noise sources. Reliability and stress testing was also began for polycrystalline mercuric iodide PVD and PIB detectors. These are simplified detectors based upon a stripe electrode or circular electrode structure. The detectors were stressed under various voltage bias, temperature and time conditions. The effects of the stress tests on the detector dark current and sensitivity were determined.

Paper Details

Date Published: 6 May 2004
PDF: 11 pages
Proc. SPIE 5368, Medical Imaging 2004: Physics of Medical Imaging, (6 May 2004); doi: 10.1117/12.535948
Show Author Affiliations
George Zentai, Varian Medical Systems, Inc. (United States)
Larry Partain, Varian Medical Systems, Inc. (United States)
Raisa Pavlyuchkova, Varian Medical Systems, Inc. (United States)
Cesar Proano, Varian Medical Systems, Inc. (United States)
Barry N. Breen, Real Time Radiography, Ltd. (Israel)
A. Taieb, Real Time Radiography, Ltd. (Israel)
Ofer Dagan, Real Time Radiography, Ltd. (Israel)
Michael Schieber, Real Time Radiography, Ltd. (Israel)
Haim Gilboa, Real Time Radiography, Ltd. (Israel)
Jerry Thomas, Uniformed Services Univ. of the Health Sciences (United States)


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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