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A new clinical unit for digital radiography based on a thick amorphous selenium plate: physical and psychophysical characterization.
MedLine Citation:
PMID:  21928617     Owner:  NLM     Status:  In-Process    
Abstract/OtherAbstract:
PURPOSE: Here, we present a physical and psychophysical characterization of a new clinical unit (named AcSelerate) for digital radiography based on a thick a-Se layer. We also compared images acquired with and without a software filter (named CRF) developed for reducing sharpness and noise of the images and making them similar to images coming from traditional computed radiography systems.
METHODS: The characterization was achieved in terms of physical figures of merit [modulation transfer function (MTF), noise power spectra (NPS), detective quantum efficiency (DQE)], and psychophysical parameters (contrast-detail analysis with an automatic reading of CDRAD images). We accomplished measurements with four standard beam conditions: RAQ3, RQA5, RQA7, and RQA9.
RESULTS: The system shows an excellent MTF (about 50% at the Nyquist frequency). The DQE is about 55% at 0.5 lp/mm and above 20% at the Nyquist frequency and is almost independent from exposure. The contrast-detail curves are comparable to some of the best published data for other systems devoted to imaging in general radiography. The CRF filter influences both the MTF and NPS, but it does lead to very small changes on DQE. Also the visibility of CDRAD details is basically unaltered, when the filter is activated.
CONCLUSIONS: As normally happens with detector based on direct conversion, the system presents an excellent MTF. The improved efficiency caused by the thick layer allows getting good noise characteristics and DQE results better (about 10% on average) than many of the computed radiography (CR) systems and comparable to those obtained by the best systems for digital radiography available on the market.
Authors:
Stefano Rivetti; Nico Lanconelli; Marco Bertolini; Domenico Acchiappati
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Publication Detail:
Type:  Journal Article    
Journal Detail:
Title:  Medical physics     Volume:  38     ISSN:  0094-2405     ISO Abbreviation:  Med Phys     Publication Date:  2011 Aug 
Date Detail:
Created Date:  2011-09-20     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  0425746     Medline TA:  Med Phys     Country:  United States    
Other Details:
Languages:  eng     Pagination:  4480-8     Citation Subset:  IM    
Affiliation:
Alma Mater Studiorum, Physics Department, University of Bologna, 40127 Bologna, Italy.
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