Imaging performance of a thin Lu2O3:Eu nanophosphor scintillating screen coupled to a high resolution CMOS sensor under X-ray radiographic conditions: comparison with Gd2O2S:Eu conventional phosphor screen

I. Seferis; C. Michail; I. Valais; J. Zeler; P. Liaparinos; N. Kalyvas; G. Fountos; E. Zych; I. Kandarakis; G. Panayiotakis

doi:10.1117/12.2042150

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19 March 2014 Imaging performance of a thin Lu₂O₃:Eu nanophosphor scintillating screen coupled to a high resolution CMOS sensor under X-ray radiographic conditions: comparison with Gd₂O₂S:Eu conventional phosphor screen

I. Seferis, C. Michail, I. Valais, J. Zeler, P. Liaparinos, N. Kalyvas, G. Fountos, E. Zych, I. Kandarakis, G. Panayiotakis

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Proceedings Volume 9033, Medical Imaging 2014: Physics of Medical Imaging; 90333T (2014) https://doi.org/10.1117/12.2042150
Event: SPIE Medical Imaging, 2014, San Diego, California, United States

Abstract

The purpose of the present study was to experimentally evaluate the imaging characteristics of the Lu₂O₃:Eu nanophosphor thin screen coupled to a high resolution CMOS sensor under radiographic conditions. Parameters such as the Modulation Transfer Function (MTF), the Normalized Noise Power Spectrum (NNPS) and the Detective Quantum Efficiency (DQE) were investigated at 70 kVp under three exposure levels (20 mAs, 63 mAs and 90 mAs). Since Lu₂O₃:Eu emits light in the red wavelength range, the imaging characteristics of a 33.3 mg/cm² Gd₂O₂S:Eu conventional phosphor screen were also evaluated for comparison purposes. The Lu₂O₃:Eu nanophosphor powder was produced by the combustion synthesis, using urea as fuel. A scintillating screen of 30.2 mg/cm² was prepared by sedimentation of the nanophosphor powder on a fused silica substrate. The CMOS/Lu₂O₃:Eu detector`s imaging characteristics were evaluated using an experimental method proposed by the International Electrotechnical Commission (IEC) guidelines. It was found that the CMOS/Lu2O₃:Eu nanophosphor system has higher MTF values compared to the CMOS/Gd₂O₂S:Eu sensor/screen combination in the whole frequency range examined. For low frequencies (0 to 2 cycles/mm) NNPS values of the CMOS/Gd₂O₂S:Eu system were found 90% higher compared to the NNPS values of the CMOS/Lu₂O₃:Eu nanophosphor system, whereas from medium to high frequencies (2 to 13 cycles/mm) were found 40% higher. In contrast with the CMOS/ Gd₂O₂S:Eu system, CMOS/Lu₂O₃:Eu nanophosphor system appears to retain high DQE values in the whole frequency range examined. Our results indicate that Lu₂O₃:Eu nanophosphor is a promising scintillator for further research in digital X-ray radiography.

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I. Seferis, C. Michail, I. Valais, J. Zeler, P. Liaparinos, N. Kalyvas, G. Fountos, E. Zych, I. Kandarakis, and G. Panayiotakis "Imaging performance of a thin Lu₂O₃:Eu nanophosphor scintillating screen coupled to a high resolution CMOS sensor under X-ray radiographic conditions: comparison with Gd₂O₂S:Eu conventional phosphor screen", Proc. SPIE 9033, Medical Imaging 2014: Physics of Medical Imaging, 90333T (19 March 2014); https://doi.org/10.1117/12.2042150

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