Appl Phys B (2009) 95: 131–139 DOI 10.1007/s00340-009-3408-0 Imaging performance and light emission efﬁciency of Lu 2 SiO 5 :Ce (LSO:Ce) powder scintillator under X-ray mammographic conditions C. Michail · A. Toutountzis · S. David · N. Kalyvas · I. Valais · I. Kandarakis · G.S. Panayiotakis Received: 7 June 2008 / Revised version: 30 December 2008 / Published online: 3 March 2009 © Springer-Verlag 2009 Abstract The aim of the present study was to measure the imaging transfer characteristics and the luminescence efﬁ- ciency (XLE) of a Lu 2 SiO 5 :Ce (LSO:Ce) powder scintilla- tor for use in X-ray mammography detectors. An LSO:Ce powder scintillating screen, with a coating thickness of 25 mg/cm 2 , was prepared in our laboratory. The imaging performance of the screen was assessed by experimental de- termination of the modulation transfer function (MTF) and the detective quantum efﬁciency (DQE) as well as single in- dex image quality parameters such as noise equivalent pass band (Ne) and informational efﬁciency (n I ). A theoretical model, describing radiation and light transfer, was ﬁtted to experimental MTF values in order to estimate optical prop- erties of the scintillator. Screen irradiation was performed under exposure conditions employed in mammographic ap- plications (27 kVp, 63 mAs). MTF was determined by the square wave response function (SWRF) method. Results showed that LSO:Ce exhibits high MTF and DQE values, which are comparable to those of the commercially used Gd 2 O 2 S:Tb. Considering our image quality parameters and luminescence efﬁciency results as well as the fast response of the LSO:Ce scintillator screen (40 ns), this material can be considered for use in X-ray mammographic detectors. PACS 07.85.Fv · 42.30.Lr · 85.60.Gz C. Michail · A. Toutountzis · S. David · N. Kalyvas · I. Valais · G.S. Panayiotakis ( ) Department of Medical Physics, Medical School, University of Patras, 265 00 Patras, Greece e-mail: panayiot@upatras.gr N. Kalyvas · I. Valais · I. Kandarakis Department of Medical Instruments Technology, Technological Educational Institution of Athens, Ag. Spyridonos, Aigaleo, 122 10 Athens, Greece 1 Introduction Cerium (Ce 3+ )-doped scintillators are of particular inter- est for medical imaging applications due to their very fast response [1]. This is attributed to a 5d → 4f electronic transition in the Ce 3+ ion [2, 3]. Lutetium oxyorthosilicate Lu 2 SiO 5 :Ce (LSO) is a scintillator with a number of advan- tages such as high light yield (26000 photons/MeV) and lu- minescence efﬁciency, high density (7.4 g/cm 3 ), fast decay time (40 ns), high effective atomic number (66) and excel- lent chemical stability [4–7]. Furthermore, LSO:Ce emits light in the blue region, which renders it compatible with a large number of optical sensors. In single-crystal form LSO:Ce has already been used in several non-imaging ap- plications such as gamma-ray detection in nuclear physics, high-energy physics and environmental monitoring [4, 5]. LSO has also replaced Bi 4 Ge 3 O 12 (BGO) scintillators in some positron emission tomography (PET) scanners. How- ever, to our knowledge LSO:Ce in powder form has not yet been employed in medical imaging applications, i.e. in medical radiographic detectors where powder scintil- lating screens are very often used. In previous works we have reported preliminary data on the performance of an LSO screen [8–10]. In the present study a systematic ex- perimental and theoretical investigation of the light emis- sion efﬁciency and the imaging performance of an LSO:Ce powder scintillating screen was performed under X-ray mammography conditions. Various parameters, such as the X-ray luminescence efﬁciency (XLE), the detector quantum gain (DQG) and spatial frequency-dependent imaging pa- rameters, such as the modulation transfer function (MTF), the noise transfer function (NTF) and the detective quantum efﬁciency (DQE), were assessed. In addition, single index image quality parameters such as the noise equivalent pass