TY - JOUR
T1 - A new clinical unit for digital radiography based on a thick amorphous Selenium plate
T2 - Physical and psychophysical characterization
AU - Rivetti, Stefano
AU - Lanconelli, Nico
AU - Bertolini, Marco
AU - Acchiappati, Domenico
PY - 2011/8
Y1 - 2011/8
N2 - 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 lpmm 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.
AB - 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 lpmm 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.
KW - amorphous selenium
KW - digital radiology
KW - direct conversion detector
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U2 - 10.1118/1.3605471
DO - 10.1118/1.3605471
M3 - Article
C2 - 21928617
AN - SCOPUS:79961083699
VL - 38
SP - 4480
EP - 4488
JO - Medical Physics
JF - Medical Physics
SN - 0094-2405
IS - 8
ER -