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Proceedings Paper

Energy-dependent quantum detective efficiency (QDE) measurements of a photon-counting CdTe detector array used for the scanning-beam digital x-ray (SBDX) system
Author(s): Koji Iwata; Josh M. Star-Lack; Edward G. Solomon; Joseph A Heanue; Rick E. Walkup; Robert Erhard Melen
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Paper Abstract

The Scanning-Beam Digital X-ray (SBDX) system utilizes a scanning x-ray pencil beam and a small-area detector array for low-dose cardiac angiography with tomographic imaging capabilities. For the system to provide adequate signal-to-noise ratios, the multi-element detector must be highly efficient and capable of high photon count rates. Cadmium telluride (CdTe) is well suited to these purposes. The CdTe SBDX detector is a direct-conversion photon-counting device consisting of 2304 elements. The efficiency of the detector is a function of several factors including the incident photon energy, the fluorescence properties of CdTe, and the discriminator threshold that determines whether sufficient energy was deposited in an element to register a count. For maximum efficiency, the discriminator threshold must be set low enough to detect CdTe k-fluorescence photons (23-31 keV), but not so low as to register false counts from electronic noise. The purpose of this investigation was to evaluate the energy-dependent quantum detective efficiency (QDE) of a new lower-noise SBDX detector design and to determine whether adequately low thresholds can be achieved. Experiments were performed using metal fluorescer foils to generate quasi-monochromatic x-ray beams with energies of 17.5, 25.3, and 46.0 keV. The resulting spectral purities were high, although fluence rates were low. The measured QDE values at 17.5, 25.3, and 46.0 keV were 60%, 76%, and 86% repsectively.

Paper Details

Date Published: 5 June 2003
PDF: 8 pages
Proc. SPIE 5030, Medical Imaging 2003: Physics of Medical Imaging, (5 June 2003); doi: 10.1117/12.480253
Show Author Affiliations
Koji Iwata, Univ. of California/San Francisco (United States)
Josh M. Star-Lack, NexRay, Inc. (United States)
Edward G. Solomon, NexRay, Inc. (United States)
Joseph A Heanue, NexRay, Inc (United States)
Rick E. Walkup, NexRay, Inc. (United States)
Robert Erhard Melen, NexRay, Inc. (United States)

Published in SPIE Proceedings Vol. 5030:
Medical Imaging 2003: Physics of Medical Imaging
Martin J. Yaffe; Larry E. Antonuk, Editor(s)

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