Light emission efficiency and imaging properties of YAP:Ce granular phosphor screens

• Published in: Applied physics. A, Materials science & processing Vol. 89; no. 2; pp. 443 - 449
• Main Authors: KALIVAS, N, VALAIS, I, NIKOLOPOULOS, D, KONSTANTINIDIS, A, GAITANIS, A, CAVOURAS, D, NOMICOS, C. D, PANAYIOTAKIS, G, KANDARAKIS, I
• Format: Journal Article
• Language: English
• Published: Berlin Springer 01-11-2007; Springer Nature B.V
• Subjects: Applied physics; Cerium; Condensed matter: electronic structure, electrical, magnetic, and optical properties; Diagnostic systems; Efficiency; Emission analysis; Exact sciences and technology; Fused silica; Irradiation; Light emission; Materials science; Medical imaging; Medical materials; Optical properties and condensed-matter spectroscopy and other interactions of matter with particles and radiation; Other luminescence and radiative recombination; Phosphors; Physics; Positron emission; Quantum efficiency; Radiology; Scintillation counters; Screens; Signal to noise ratio; Single crystals; Synchrotrons; X ray imagery; X ray tubes; Aluminium oxide; Radiation effects; Doping; Luminescence; Quantum yield; X-ray imaging; Monocrystals; Scintillator; Gamma radiation; Phosphors; Cerium additions; X radiation; Yttrium oxide; Synchrotron radiation
• ISSN: 0947-8396; 1432-0630
• DOI: 10.1007/s00339-007-4173-8

Phosphor materials are used in medical imaging combined with radiographic film or other photodetectors. Cerium (Ce3+) -doped scintillators are of particular interest for medical imaging, because of their very fast response. YAP:Ce scintillator-based image detectors have already been evaluated in single-crystal form and under conditions of positron emission tomography and synchrotron or γ-ray irradiation. Furthermore, YAP:Ce phosphor has been evaluated in conjunction with radiographic films. The present work reports experimental and theoretical data concerning the light output absolute luminescence efficiency (AE) of the YAP:Ce screens under irradiation conditions employed in medical X-ray projection imaging (i.e., in diagnostic radiology). projection imaging (i.e., in diagnostic radiology). YAP:Ce phosphor screens with surface densities ranging between 53 and 110 mg/cm2 were prepared by sedimentation on fused silica substates in our laboratory. The resulted surface density of the screens was determined by dividing the phosphor mass deposited on the screen surface with the area of the surface. Additionally this work addresses the imaging performance of YAP:Ce by estimation of the detective quantum efficiency (DQE), i.e., the square of the signal to noise ratio transfer. Absolute efficiency was found to decrease with X-ray tube voltage for for YAP:Ce phosphor. The highest experimental efficiency was obtained for the 53.7 mg/cm2 and 88.0 mg/cm2 YAP:Ce screens. The highest DQE value was found for the 88.0 mg/cm2 screen irradiated at 60 kVp.