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Proceedings Paper

Prototype high detective quantum efficiency imaging panel based on a fiber-optic scintillation glass array (FOSGA) for megavoltage imaging
Author(s): Sanjiv Samant; Jim Baciak; Arun Gopal
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Paper Abstract

Megavoltage imaging has applications in nondestructive imaging for homeland security, radiotherapy, and industrial manufacturing. Current commercial systems are limited by low image quality as measured by detective quantum efficiency (DQE). These systems yield measured DQE=0.01-0.02, limiting efficacy for detection based on automated signal processing. Past efforts to improve DQE have included novel scintillators and manufacturing of large crystal structures. An alternative novel design for a 2D x-ray imager, based on a modification of existing amorphous silicon (a:Si) or flat-panel imagers, is presented. The panel utilizes a fiber-optic scintillation glass array (FOSGA) consisting of scintillation fibers bundled within a pixilated thick sintered tungsten housing. The tungsten housing is constructed using a lithographic manufacturing technique for high fabrication accuracy. The Tb-doped fibers emit light in the 555-565nm range (matched to the sensitive region of current a:Si photodiodes), with a decay time of 2ms (100-to-40%). Monte Carlo simulations, linear cascaded systems analyses, and film studies have been carried out to validate and optimize image quality for radiation beams in the 1-6MV range. An 8cmx8cm prototype array was fabricated using Tb-doped fibers (9mm length, 0.9mm diameter) loaded into a tungsten matrix (1.1mm pixel pitch, 0.1mm septa), yielding measured DQE=0.05 (vs theoretical DQE=0.07) for 6MV imaging , an order of magnitude improvement in image quality over current commercial imagers. Design parameters of a large field-of-view FOSGA imager for cargo container security imaging are presented: 5cm thick FOSGA array, 0.4-1mm pixel pitch, 50-70% fill factor, DQE>0.2 for 1-6MV range.

Paper Details

Date Published: 27 September 2011
PDF: 13 pages
Proc. SPIE 8142, Hard X-Ray, Gamma-Ray, and Neutron Detector Physics XIII, 81420P (27 September 2011); doi: 10.1117/12.896946
Show Author Affiliations
Sanjiv Samant, Univ. of Florida (United States)
Jim Baciak, Pacific Northwest National Lab. (United States)
Arun Gopal, Univ. of Florida (United States)

Published in SPIE Proceedings Vol. 8142:
Hard X-Ray, Gamma-Ray, and Neutron Detector Physics XIII
Larry A. Franks; Ralph B. James; Arnold Burger, Editor(s)

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