A comparative investigation of Lu2SiO5:Ce and Gd2O2S:Eu phosphor scintillators for use in a medical imaging detectors

The dominant powder scintillator in most medical imaging modalities for decades is Gd
₂
O
₂
S:Tb due to the very good intrinsic properties and overall efficiency. Except Gd
₂
O
₂
S:Tb there are alternative powder phosphor scintillators like Lu
₂
SiO
₅
:Ce and Gd
₂
O
₂
S:Eu that has been suggested for use in various medical imaging modalities. Gd
₂
O
₂
S:Eu emits red light and can be combined mainly with digital detectors like CCDs and wavelength selective detectors. Lu
₂
SiO
₅
:Ce emits blue light and can be combined with blue sensitivity films, photocathodes and some photodiodes. For the purpose of this study two Lu
₂
SiO
₅
:Ce and Gd
₂
O
₂
S:Eu powder phosphor scintillators with screen coating thicknesses of 25 and 33 mg/cm
²
respectively, were prepared by the method of sedimentation in our laboratory. The output efficiency of the phosphor screens were evaluated with respect to incident exposure rate and the spatial frequency dependent Modulation Transfer Function (MTF). Furthermore the spectral compatibility of those materials with various detectors was evaluated. Results were compared to published data for the commercially employed dasiaKodak Min-R film-screen systempsila, based on a 31.7 mg/cm
²
thick Gd
₂
O
₂
S:Tb phosphor. For Gd
₂
O
₂
S:Eu, MTF data were found comparable to those of Gd
₂
O
₂
S:Tb, while the MTF of Lu
₂
SiO
₅
:Ce was even higher. The different spectral compatibility of these phosphors could be interesting for application based on red and blue sensitive optical sensors respectively.