International audienceDigital X-ray imaging systems for MeV range photon beams are based on a combination of a scintillator screen and either a camera or an amorphous silicon array. To limit dose rate on electronics and enhance imaging device lifetime, the scintillator screen is mirror-coupled to the camera. Performances of such devices are a compromise between exposure time and spatial resolution. These technical characteristics are especially scintillator dependent. In this paper, we present a performance evaluation of six different scintillators with a 9 MeV Bremsstrahlung X-ray source. The tested scintillators are composed of one micro-structured CsI(Tl) scintillator, two phosphor (GOS) screens and three transparent scintillators. These scintillators present a wide range of density, thickness and conversion efficiency. Each scintillator's performance is assessed based on the combination of light output (ADU number) and modulation transfer function (spatial resolution) obtained. The results are helpful to guide design and engineering of high energy imaging devices adapted to specific requirements

Cherepy, N.

Eck, D.

Eleon, C.

Estre, N.

Payan, E.

Tamagno, L.

Tisseur, D.

English

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Performance evaluation of several well-known and new
scintillators for MeV X-ray imaging
D. Tisseur, N. Estre, L. Tamagno, C. Eleon, D. Eck, E. Payan, N. Cherepy
To cite this version:
D. Tisseur, N. Estre, L. Tamagno, C. Eleon, D. Eck, et al.. Performance evaluation of several well-
known and new scintillators for MeV X-ray imaging. 2018 IEEE Nuclear Science Symposium and
Medical Imaging Conference, Nov 2018, Sydney, Australia. pp.1-3, ￿10.1109/NSSMIC.2018.8824663￿.
￿cea-02338723￿
 Performance evaluation of several well-known and 
new scintillators for MeV X-ray imaging 
David Tisseur, Nicolas Estre, Léonie Tamagno, Cyrille Eleon,  Daniel Eck, Emmanuel Payan, Nerine Cherepy
Abstract– Digital X-ray imaging systems for MeV range 
photon beams are based on a combination of a scintillator screen 
and either a camera or an amorphous silicon array. To limit dose 
rate on electronics and enhance imaging device lifetime, the 
scintillator screen is mirror-coupled to the camera. Performances 
of such devices are a compromise between exposure time and 
spatial resolution. These technical characteristics are especially 
scintillator dependent. In this paper, we present a performance 
evaluation of six different scintillators with a 9 MeV 
Bremsstrahlung X-ray source. The tested scintillators are 
composed of one micro-structured CsI(Tl) scintillator, two 
phosphor (GOS) screens and three transparent scintillators. 
These scintillators present a wide range of density, thickness and 
conversion efficiency. Each scintillator’s performance is assessed 
based on the combination of light output (ADU number) and 
modulation transfer function (spatial resolution) obtained. The 
results are helpful to guide design and engineering of high energy 
imaging devices adapted to specific requirements. 
 
Index Terms — Radioscopy; High-Energy X-ray; Linac; 
Scintillator; X-ray imaging 
I. INTRODUCTION 
Many papers in the literature report performance of various 
scintillators for digital imaging in the range of classical X-ray 
tube energy [1][2][3] or synchrotron applications [4][5]. 
Concerning imaging in MeV range for non-destructive testing 
(NDT), literature is less abundant [6]. In this paper, we present 
a study of scintillator imaging performance for a 9 MeV linear 
accelerator beam. We selected well-known phosphor screens, 
micro-structured, single crystal and transparent ceramic 
scintillators. These tests are intended to help define the desired 
scintillator properties, geometry and optical configuration to 
optimize our 9 MeV radiography system. 
 
II. SCINTILLATORS PERFORMANCE EVALUATION SET-UP 
Tests were performed with a 9-MeV Linear accelerator [8] in 
a cell named KROTOS at CEA Cadarache [9]. The 
scintillators evaluated were: two GOS (Gd2O2S:Tb) phosphor 
powder screens (Medex from AST, Lanex Fast Back from 
Kodak) one micro-structured CsI(Tl) scintillator provided by 
Hamamatsu, and three transparent scintillators - BGO 
(Bi4Ge3O12) from Saint Gobain, LYSO (Lu1.9Y0.1SiO5, Cerium 
content: 0.5mol%) from JT Crystal Technology and GLO 
(Gd0.3Lu1.6Eu0.1O3) from Lawrence Livermore National 
 
D. Tisseur, N. Estre, L. Tamagno, C. Eleon, D. Eck, E. Payan, are with 
CEA, DEN, Cadarache, Nuclear Measurement Laboratory, F-13108 Saint-
Paul-lez-Durance, France. N. Cherepy is with the Lawrence Livermore 
National Laboratory, L168, Livermore, CA, 94550, USA. 
Laboratory [10]. These scintillators present a wide range of 
density, thickness and conversion efficiency. Tables I and II 
summarize the physical and optical properties of the 
scintillators studied. Each scintillator screen is imaged by a 
low noise S-CMOS 2160x2560 pixels (ANDOR Zyla 5.5) 
camera through a 45° tilted mirror in a light-tight box. A lead 
block prevents damage to the camera (see Fig. 1).  The 
average detector dose rate was 0.92 mGy/s. 
 
 
 
Fig. 1. Experimental setup.  
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
The light output measured for each scintillator results from its 
stopping power (primarily determined by density in the MeV 
pair-production regime), luminosity (a constant for each 
scintillator), and optical configuration (optical scattering, 
9 MeV beam 
Zyla camera  
TABLE I 
SCINTILLATOR PHYSICAL AND OPTICAL CONFIGURATION USED 
Scintillator  Density 
(g/cm3) 
Thickness  Configuration 
Medex, GOS 7.32 780 µm On 2 mm brass plate 
Lanex, GOS 7.32 290 µm See [11] 
CsI 4.51 2 mm On 2 mm Cu plate 
BGO 7.13 3 mm  
Blackened surfaces 
other than exit 
surface 
LYSO 7.25 25 mm 
GLO 9.10 1.58 mm 
 
 
 
 
TABLE II 
SURVEY OF CHARACTERISTICS OF SELECTED SCINTILLATORS 
Scintillator 
name 
Surface 
density in 
mg/cm2 
Light yield 
(photons/MeV) 
Optical  
index 
Medex 347  65000  
Lanex Fast Back 134  65000  
CsI 902  54000  
BGO 899  8000-10000 2.15 
LYSO 18500  30000 1.82 
GLO 1438 55000 1.89 
 
 
 
 reflective or black backing).  Light output was measured via 
mean ADU number in a 50 pixels x 50 pixels region of 
interest of the image with an exposure time of 1 s. To avoid 
photonic noise, 10 images are averaged. A 5 cm x 5 cm x 10 
cm copper block placed in front of the scintillator was used for 
modulation transfer function (MTF) evaluation with classical 
edge method. Edge spread function (ESF) was fitted with a 
combination of 2 Gauss error functions. Line spread function 
was obtained from the analytical derivative of the ESF. Then 
the MTF was given by analytical LSF Fourier transform. 
Considering the distance from the linear accelerator to the 
detector box of 3125 mm, source size blur was considered to 
be negligible. 
III.  RESULTS AND ANALYSIS  
In order to compare the six different scintillators, LYSO was 
selected as the reference screen (best known light yield with 
±10% uncertainty), and all as-measured light output values 
were normalized to LYSO, but are not normalized for 
thickness, density or any other physical property. Each MTF 
curve for each scintillator and optical MTF has been evaluated 
(see Fig. 2). In order to be independent of the optical MTF, 
scintillators MTF have been corrected from optical MTF. 
Spatial resolution is computed using [12] definition: 
𝑆𝑝𝑎𝑡𝑖𝑎𝑙 𝑟𝑒𝑠𝑜𝑙𝑢𝑡𝑖𝑜𝑛 =
1
2 ∗ 𝑀𝑇𝐹20%
 
 
 
Fig. 2. MTF corresponding to the six scintillators and optical part. 
Table III summarizes the results obtained. The highest light 
output was obtained with CsI. Thanks to CsI micro-columnar 
structure, spatial resolution (994 µm) is better than Medex 
(1259 µm) and LYSO (1037 µm). With the highest thickness 
(25 mm), LYSO scintillator has a light output comparable to 
Medex with a little better spatial resolution (1037 µm). The 
best spatial resolution is achieved with GLO (401 µm). The 
1.58 mm thick GLO scintillator was 2 times brighter than the 
3 mm thick BGO crystal, both prepared with black backing to 
eliminate scattered and back-reflected scintillation light (see 
Fig. 3). 
 
Fig. 3. Measured scintillator light output vs spatial resolution 
To analyze our results on scintillator performance, we have 
performed MCNP6 Monte Carlo simulation [13] and 
compared the measurements to the expected results for 
transparent scintillators (BGO, GLO). Simulations are in 
accordance with measurement excepted for GLO. Work is 
under progress to understand this result. 
IV.   CONCLUSION AND PERSPECTIVES 
This study measured imaging performance with a 9 MeV 
Bremsstrahlung source of a wide range of scintillators 
including the well-known BGO, CsI GOS and newer 
scintillators, LYSO, GLO. The completed final paper will 
present more details particularly in experimental data and 
simulation analysis. 
V.     REFERENCES 
 
[1] S. Vedantham et al., Full Breast Digital Mammographic Imaging with 
an Amorphous Silicon-based Flat Panel Detector: Physical 
Characteristics of a Clinical Prototype, Med. Phys. 27: 558-567, 2000.  
[2] K.W. Jee, L.E. Antonuk, Y. El-Mohri, Q. Zhao, System performance of 
a prototype flat-panel imager operated under mammographic 
conditions, Med Phys. Jul;30(7):1874-90, 2003. 
[3] M. Nikl, Scintillation detectors for X-rays, Meas. Sci. Technol. 17 R37, 
2006   
[4] A. Koch, Lens coupled scintillating screen-CCD X-ray area detector 
with a high detective quantum efficiency, Nucl. Instrum. Meth. A 
348 654, 1994 
[5] H. Xie, G. Du, B. Deng, R. Chen, T. Xiao, Study of Scintillator thickness 
optimization of lens-coupled X-ray imaging detectors, Journal of 
instrumentation, vol. 11, num. 03, 2016 
[6] S. Baker et al., Scintillator efficiency study with MeV xrays, Proc. SPIE, 
vol. 9213, pp. 92130, 2014. 
[7] D. Partouche-Sebban et al., Multi-MeV Flash Radiography in Shock 
Physics Experiments: Specific Assemblages of Monolithic Scintillating 
Crystals for Use in CCD-Based Imagers, January 2010, X-Ray Optics 
and Instrumentation 2010(3), DOI 10.1155/2010/156984 
[8] N. Estre et al., High-energy X-ray imaging applied to nondestructive 
characterization of large nuclear waste drums, IEEE Trans. Nucl. Sci., 
vol. 62, no. 6, (2015) p. 3104  
[9] N. Estre, L. Berge, E. Payan, Fast megavoltage X-rays radioscopy, 
Conference: 2016 IEEE NSS/MIC/RTSD,October 2016 
[10] N.J. Cherepy et al., Transparent Ceramic Scintillators for Gamma 
Spectroscopy and MeV Imaging, SPIE Optical Engineering+ 
Applications, 95930P-95930P-7 (2015) 
[11] ©Eastman Kodak Company, 2005, Film-screen systems and KODAK 
LANEX screen, available at http://www.ndt-service.de/wp-
content/uploads/2012/02/Lanex-screens.pdf 
[12] ISO 16371-1, Industrial computed radiography with storage phosphor 
imaging plates — Part 1: Classification of systems 
[13] J.T. Goorley, et al., “Initial MCNP6 Release Overview – MCNP6 
Version 1.0”, LANL  Report, LA-UR-13-22934 (2013). 
0
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Sensitivity 
Spatial resolution vs sensitivity 
Medex
Lanex
LYSO
CsI
GLO
BGO
TABLE III 
SCINTILLATOR PERFORMANCE SUMMARY 
 
Scintillator 
name 
Measured light 
output 
Spatial resolution 
in µm 
Medex 0.96 1259 
Lanex  0.12 746 
CsI 1.52 994 
BGO 0.12 625 
LYSO 1 1037 
GLO 0.21 401 
 
 
 
 


Performance evaluation of several well-known and new scintillators for MeV X-ray imaging

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Performance evaluation of several well-known and new scintillators for MeV X-ray imaging

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