Valutazione delle propriet\ue0 fisiche e chimiche dei camici anti-X reperibili sul mercato italiano\u201d Atti Convegno Nazionale di radioprotezione: Sicurezza e Qualit\ue0 in Radioprotezione

Dispositivi di Protezione Individuali (DPI)come i camici anti-X sono stati studiati al fine di verificarne le propriet\ue0 schermanti che dipendono sia dal tipo e spessore di materiale, che dallo spettro di energia della radiazione RX incidente.Storicamente erano costituiti di piombo, ma a causa dei problemi ambientali e del peso eccessivo del DPI, si cercano materiali alternativi. Lo scopo del presente lavoro \ue8 di analizzare nuovi camici reperibili sul mercato, vericare l'assenza di piombo ed analizzare le propriet\ue0 fisiche e chimich

A new clinical unit for digital radiography based on a thick amorphous Selenium plate: Physical and psychophysical characterization

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

Comparison of different computed radiography systems: Physical characterization and contrast detail analysis

Purpose: In this study, five different units based on three different technologies\u2014traditional computed radiography (CR) units with granular phosphor and single-side reading, granular phosphor and dual-side reading, and columnar phosphor and line-scanning reading\u2014are compared in terms of physical characterization and contrast detail analysis. Methods: The physical characterization of the five systems was obtained with the standard beam condition RQA5. Three of the units have been developed by FUJIFILM (FCR ST-VI, FCR ST-BD, and FCR Velocity U), one by Kodak (Direct View CR 975), and one by Agfa (DX-S). The quantitative comparison is based on the calculation of the modulation transfer function (MTF), noise power spectrum (NPS), and detective quantum efficiency (DQE). Noise investigation was also achieved by using a relative standard deviation analysis. Psychophysical characterization is assessed by performing a contrast detail analysis with an automatic reading of CDRAD images. Results: The most advanced units based on columnar phosphors provide MTF values in line or better than those from conventional CR systems. The greater thickness of the columnar phosphor improves the efficiency, allowing for enhanced noise properties. In fact, NPS values for standard CR systems are remarkably higher for all the investigated exposures and especially for frequencies up to 3.5 lp/mm. As a consequence, DQE values for the three units based on columnar phosphors and line-scanning reading, or granular phosphor and dual-side reading, are neatly better than those from conventional CR systems. Actually, DQE values of about 40% are easily achievable for all the investigated exposures. Conclusions: This study suggests that systems based on the dual-side reading or line-scanning reading with columnar phosphors provide a remarkable improvement when compared to conventional CR units and yield results in line with those obtained from most digital detectors for radiography