A novel epitaxially grown LSO-based thin-film scintillator for micro-imaging using hard synchrotron radiation

Abstract

The efficiency of high-resolution pixel detectors for hard X-rays is nowadays one of the major criteria which drives the feasibility of imaging experiments and in general the performance of an experimental station for synchrotron-based microtomography and radiography. Here the luminescent screen used for the indirect detection is focused on in order to increase the detective quantum efficiency: a novel scintillator based on doped Lu(2)SiO(5) (LSO), epitaxially grown as thin film via the liquid phase epitaxy technique. It is shown that, by using adapted growth and doping parameters as well as a dedicated substrate, the scintillation behaviour of a LSO-based thin crystal together with the high stopping power of the material allows for high-performance indirect X-ray detection. In detail, the conversion efficiency, the radioluminescence spectra, the optical absorption spectra under UV/visible-light and the afterglow are investigated. A set-up to study the effect of the thin-film scintillator's temperature on its conversion efficiency is described as well. It delivers knowledge which is important when working with higher photon flux densities and the corresponding high heat load on the material. Additionally, X-ray imaging systems based on different diffraction-limited visible-light optics and CCD cameras using among others LSO-based thin film are compared. Finally, the performance of the LSO thin film is illustrated by imaging a honey bee leg, demonstrating the value of efficient high-resolution computed tomography for life sciences.

Single Crystalline Film Scintillators Based on the Orthosilicate, Perovskite and Garnet Compounds

“…During the last three decades the liquid phase epitaxy (LPE) proved to be a beneficial method for the development of luminescent materials based on single crystalline films (SCF) of oxide compounds, such as garnets, perovskites, sapphire, silicates and tungstates [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15]. Apart from the laser media [1], cathodoluminescent screens [2][3][4][5] and α-and β-scintillators [6][7][8], developed in the 80-90th of the last century on the base of rare-earth doped SCF of Y 3 Al 5 O 12 (YAG), Lu 3 Al 5 O 12 (LuAG) and Gd 3 Ga 5 O 12 (GGG) garnets, the application fields of such SCFs in the last decade are extended to X-ray visualization screens [9][10][11][12][13][14][15].…”

“…Apart from the laser media [1], cathodoluminescent screens [2][3][4][5] and α-and β-scintillators [6][7][8], developed in the 80-90th of the last century on the base of rare-earth doped SCF of Y 3 Al 5 O 12 (YAG), Lu 3 Al 5 O 12 (LuAG) and Gd 3 Ga 5 O 12 (GGG) garnets, the application fields of such SCFs in the last decade are extended to X-ray visualization screens [9][10][11][12][13][14][15]. Namely, the fast development of microimaging techniques using X-ray or synchrotron radiation for applications in microtomography in biology and medicine strongly demands scintillating screens with spatial resolution in the micron or even sub-micron ranges [12][13][14][15]. Recently for this task, X-ray image detectors based on SCF screens of YAG:Ce, GGG:Tb and LuAG:Eu garnets, microscope optics, low-noise CCD camera and operated with X-ray energies of 10-50 keV have been developed at ESRF [11,12].…”

“…To increase further the spatial resolution of X-ray detectors in the sub-µm range the SCF scintillating screens emitting the blue or UV ranges [12] or scintillation screens with complex emission spectrum in blue/or UV and visible ranges [13,14] are necessary. Registration of images in the blue or even in the UV range could increase the spatial resolution R of a detector according to the formula: R~0.61*λ/NA (1), where λ is the emission wavelength, NA is the numerical aperture of the optics [12].…”

Reflection on multilayer mirrors: beam profile and coherence properties

“…Fig. 3 shows the measurement results for the micro-roughness in comparison to a super polished Si-substrate as well as pictures of the corresponding wave fronts acquired at ESRF beamline ID19 (details on the applied protocol are published) 10,14,20,21 . Mainly on the Pd/B 4 C coating a significant decrease of the micro-roughness (0.69 nm rms) of factor 8 is found while the Mo/Si (0.16 nm rms) shows a factor of two decrease compared to the uncoated Si (0.08 nm rms).…”

X-ray phase contrast tomography from whole organ down to single cells

“…This kind of detector is usually used at synchrotron sources where a resolution down to below 1 µm is possible. 25 The optical system behind the scintillator transmits only a small part of the generated light to the camera, but the high flux provided by the liquid metal source enables the use of this kind of detectors also in the laboratory with reasonable exposure times. With the detector used here, a resolution of about 1.5 µm could be achieved.…”