e-Περιοδικό Επιστήμης & Τεχνολογίας

e-Journal of Science & Technology, (e-JST)

Light emission efficiency of GdAlO₃:Ce (GAP:Ce) powder screens under X-ray radiography conditions

 A. Toutountzis¹, C. Michail¹, I. Valais², S. David¹, N. Kalyvas², P. Liaparinos² and I. Kandarakis^2*

 ¹ Department of Medical Physics, Medical School, University of Patras, 265 00 Patras, Greece

² Department of Medical Instruments Technology, Technological Educational Institution of Athens

Ag. Spyridonos, Aigaleo, 122 10 Athens, Greece

^* Corresponding author:  kandarakis@teiath.gr   

 Abstract. The aim of this study was to evaluate the performance of GdAlO₃:Ce powder scintillator screens for use in medical imaging applications. This powder phosphor, also known as GAP:Ce scintillator, is a non-hygroscopic material, emitting blue light with short decay time and it has never been used in medical imaging. Various scintillator screens with coating thickness, ranging from 14.7 to 121.1 mg/cm², were prepared in our laboratory from GdAlO₃:Ce powder (Phosphor Technology, Ltd) by sedimentation on silica substrates. The Quantum Detection Efficiency (QDE) and Energy Absorption Efficiency (EAE) were evaluated. Absolute luminescence efficiency measurements were performed under exposure conditions employed in diagnostic radiology (50-140 kV, 63 mAs), using an experimental setup based on a photomultiplier tube. The emission spectrum of GAP:Ce, after calculating the matching factor, was found compatible with various existing optical detectors. QDE and EAE of GAP, comparing to YAP has exhibited higher values.  Absolute Efficiency values were found to increase with increasing X-ray tube voltage. Although for values higher than 120 kVp a decrease was observed.

Keywords: Inorganic Scintillators; QDE; EAE; Radiation detectors; GdAlO₃:Ce.

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