Direct measurement of Lubberts effect in CsI:Tl scintillators using single x-ray photon imaging

Adrian Howansky; A. R. Lubinsky; S. K. Ghose; Katsuhiko Suzuki; Wei Zhao

doi:10.1117/12.2255561

Direct measurement of Lubberts effect in CsI:Tl scintillators using single x-ray photon imaging

Adrian Howansky
, A. R. Lubinsky
, S. K. Ghose
, Katsuhiko Suzuki
, Wei Zhao

Radiology

Stony Brook University
Brookhaven National Laboratory
Hamamatsu Photonics K.K.

Research output: Chapter in Book/Report/Conference proceeding › Conference contribution › peer-review

16 Scopus citations

Abstract

The imaging performance of an indirect flat panel detector (I-FPD) is fundamentally limited by that of its scintillator. The scintillator's modulation transfer function (MTF) varies as a function of the depth of x-ray interaction in the layer, due to differences in the lateral spread of light before detection by the optical sensor. This variation degrades the spatial frequency-dependent detective quantum efficiency (DQE(f)) of I-FPDs, and is quantified by the Lubberts effect. The depth-dependent MTFs of various scintillators used in I-FPDs have been estimated using Monte Carlo simulations, but have never been measured directly. This work presents the first experimental measurements of the depth-dependent MTF of thallium-doped cesium iodide (CsI) and terbium-doped Gd₂O₂S (GOS) scintillators with thickness ranging from 200 - 1000 μm. Light bursts from individual x-ray interactions occurring at known, fixed depths within a scintillator are imaged using an ultra-high-sensitivity II-EMCCD (image-intensifier, electron multiplying charge coupled device) camera. X-ray interaction depth in the scintillator is localized using a micro-slit beam of parallel synchrotron radiation (32 keV), and varied by translation in 50 ± 1 μm depth intervals. Fourier analysis of the imaged light bursts is used to deduce the MTF versus x-ray interaction depth z. Measurements of MTF(z,f) are used to calculate presampling MTF(f) with RQA-M3, RQA5 and RQA9 beam qualities and compared with conventional slanted edge measurements. Images of the depth-varying light bursts are used to derive each scintillator's Lubberts function for a 32 keV beam.

Original language	English
Title of host publication	Medical Imaging 2017
Subtitle of host publication	Physics of Medical Imaging
Editors	Taly Gilat Schmidt, Joseph Y. Lo, Thomas G. Flohr
Publisher	SPIE
ISBN (Electronic)	9781510607095
DOIs	https://doi.org/10.1117/12.2255561
State	Published - 2017
Event	Medical Imaging 2017: Physics of Medical Imaging - Orlando, United States Duration: Feb 13 2017 → Feb 16 2017

Publication series

Name	Progress in Biomedical Optics and Imaging - Proceedings of SPIE
Volume	10132
ISSN (Print)	1605-7422

Conference

Conference	Medical Imaging 2017: Physics of Medical Imaging
Country/Territory	United States
City	Orlando
Period	02/13/17 → 02/16/17

Keywords

Cesium iodide
Digital radiography
Flat panel detector
Lubberts
Modulation transfer function
Scintillator
Spatial resolution
Synchrotron

Access to Document

10.1117/12.2255561

Cite this

Howansky, A., Lubinsky, A. R., Ghose, S. K., Suzuki, K., & Zhao, W. (2017). Direct measurement of Lubberts effect in CsI:Tl scintillators using single x-ray photon imaging. In T. G. Schmidt, J. Y. Lo, & T. G. Flohr (Eds.), Medical Imaging 2017: Physics of Medical Imaging Article 1013209 (Progress in Biomedical Optics and Imaging - Proceedings of SPIE; Vol. 10132). SPIE. https://doi.org/10.1117/12.2255561

@inproceedings{3b3519f2871042f48b82a46a93aca5fe,

title = "Direct measurement of Lubberts effect in CsI:Tl scintillators using single x-ray photon imaging",

abstract = "The imaging performance of an indirect flat panel detector (I-FPD) is fundamentally limited by that of its scintillator. The scintillator's modulation transfer function (MTF) varies as a function of the depth of x-ray interaction in the layer, due to differences in the lateral spread of light before detection by the optical sensor. This variation degrades the spatial frequency-dependent detective quantum efficiency (DQE(f)) of I-FPDs, and is quantified by the Lubberts effect. The depth-dependent MTFs of various scintillators used in I-FPDs have been estimated using Monte Carlo simulations, but have never been measured directly. This work presents the first experimental measurements of the depth-dependent MTF of thallium-doped cesium iodide (CsI) and terbium-doped Gd2O2S (GOS) scintillators with thickness ranging from 200 - 1000 μm. Light bursts from individual x-ray interactions occurring at known, fixed depths within a scintillator are imaged using an ultra-high-sensitivity II-EMCCD (image-intensifier, electron multiplying charge coupled device) camera. X-ray interaction depth in the scintillator is localized using a micro-slit beam of parallel synchrotron radiation (32 keV), and varied by translation in 50 ± 1 μm depth intervals. Fourier analysis of the imaged light bursts is used to deduce the MTF versus x-ray interaction depth z. Measurements of MTF(z,f) are used to calculate presampling MTF(f) with RQA-M3, RQA5 and RQA9 beam qualities and compared with conventional slanted edge measurements. Images of the depth-varying light bursts are used to derive each scintillator's Lubberts function for a 32 keV beam.",

keywords = "Cesium iodide, Digital radiography, Flat panel detector, Lubberts, Modulation transfer function, Scintillator, Spatial resolution, Synchrotron",

author = "Adrian Howansky and Lubinsky, \{A. R.\} and Ghose, \{S. K.\} and Katsuhiko Suzuki and Wei Zhao",

note = "Publisher Copyright: {\textcopyright} 2017 SPIE.; Medical Imaging 2017: Physics of Medical Imaging ; Conference date: 13-02-2017 Through 16-02-2017",

year = "2017",

doi = "10.1117/12.2255561",

language = "English",

series = "Progress in Biomedical Optics and Imaging - Proceedings of SPIE",

publisher = "SPIE",

editor = "Schmidt, \{Taly Gilat\} and Lo, \{Joseph Y.\} and Flohr, \{Thomas G.\}",

booktitle = "Medical Imaging 2017",

}

Howansky, A, Lubinsky, AR, Ghose, SK, Suzuki, K & Zhao, W 2017, Direct measurement of Lubberts effect in CsI:Tl scintillators using single x-ray photon imaging. in TG Schmidt, JY Lo & TG Flohr (eds), Medical Imaging 2017: Physics of Medical Imaging., 1013209, Progress in Biomedical Optics and Imaging - Proceedings of SPIE, vol. 10132, SPIE, Medical Imaging 2017: Physics of Medical Imaging, Orlando, United States, 02/13/17. https://doi.org/10.1117/12.2255561

Direct measurement of Lubberts effect in CsI:Tl scintillators using single x-ray photon imaging. / Howansky, Adrian; Lubinsky, A. R.; Ghose, S. K. et al.
Medical Imaging 2017: Physics of Medical Imaging. ed. / Taly Gilat Schmidt; Joseph Y. Lo; Thomas G. Flohr. SPIE, 2017. 1013209 (Progress in Biomedical Optics and Imaging - Proceedings of SPIE; Vol. 10132).

Research output: Chapter in Book/Report/Conference proceeding › Conference contribution › peer-review

TY - GEN

T1 - Direct measurement of Lubberts effect in CsI:Tl scintillators using single x-ray photon imaging

AU - Howansky, Adrian

AU - Lubinsky, A. R.

AU - Ghose, S. K.

AU - Suzuki, Katsuhiko

AU - Zhao, Wei

PY - 2017

Y1 - 2017

N2 - The imaging performance of an indirect flat panel detector (I-FPD) is fundamentally limited by that of its scintillator. The scintillator's modulation transfer function (MTF) varies as a function of the depth of x-ray interaction in the layer, due to differences in the lateral spread of light before detection by the optical sensor. This variation degrades the spatial frequency-dependent detective quantum efficiency (DQE(f)) of I-FPDs, and is quantified by the Lubberts effect. The depth-dependent MTFs of various scintillators used in I-FPDs have been estimated using Monte Carlo simulations, but have never been measured directly. This work presents the first experimental measurements of the depth-dependent MTF of thallium-doped cesium iodide (CsI) and terbium-doped Gd2O2S (GOS) scintillators with thickness ranging from 200 - 1000 μm. Light bursts from individual x-ray interactions occurring at known, fixed depths within a scintillator are imaged using an ultra-high-sensitivity II-EMCCD (image-intensifier, electron multiplying charge coupled device) camera. X-ray interaction depth in the scintillator is localized using a micro-slit beam of parallel synchrotron radiation (32 keV), and varied by translation in 50 ± 1 μm depth intervals. Fourier analysis of the imaged light bursts is used to deduce the MTF versus x-ray interaction depth z. Measurements of MTF(z,f) are used to calculate presampling MTF(f) with RQA-M3, RQA5 and RQA9 beam qualities and compared with conventional slanted edge measurements. Images of the depth-varying light bursts are used to derive each scintillator's Lubberts function for a 32 keV beam.

AB - The imaging performance of an indirect flat panel detector (I-FPD) is fundamentally limited by that of its scintillator. The scintillator's modulation transfer function (MTF) varies as a function of the depth of x-ray interaction in the layer, due to differences in the lateral spread of light before detection by the optical sensor. This variation degrades the spatial frequency-dependent detective quantum efficiency (DQE(f)) of I-FPDs, and is quantified by the Lubberts effect. The depth-dependent MTFs of various scintillators used in I-FPDs have been estimated using Monte Carlo simulations, but have never been measured directly. This work presents the first experimental measurements of the depth-dependent MTF of thallium-doped cesium iodide (CsI) and terbium-doped Gd2O2S (GOS) scintillators with thickness ranging from 200 - 1000 μm. Light bursts from individual x-ray interactions occurring at known, fixed depths within a scintillator are imaged using an ultra-high-sensitivity II-EMCCD (image-intensifier, electron multiplying charge coupled device) camera. X-ray interaction depth in the scintillator is localized using a micro-slit beam of parallel synchrotron radiation (32 keV), and varied by translation in 50 ± 1 μm depth intervals. Fourier analysis of the imaged light bursts is used to deduce the MTF versus x-ray interaction depth z. Measurements of MTF(z,f) are used to calculate presampling MTF(f) with RQA-M3, RQA5 and RQA9 beam qualities and compared with conventional slanted edge measurements. Images of the depth-varying light bursts are used to derive each scintillator's Lubberts function for a 32 keV beam.

KW - Cesium iodide

KW - Digital radiography

KW - Flat panel detector

KW - Lubberts

KW - Modulation transfer function

KW - Scintillator

KW - Spatial resolution

KW - Synchrotron

UR - https://www.scopus.com/pages/publications/85020462079

U2 - 10.1117/12.2255561

DO - 10.1117/12.2255561

M3 - Conference contribution

AN - SCOPUS:85020462079

T3 - Progress in Biomedical Optics and Imaging - Proceedings of SPIE

BT - Medical Imaging 2017

A2 - Schmidt, Taly Gilat

A2 - Lo, Joseph Y.

A2 - Flohr, Thomas G.

PB - SPIE

T2 - Medical Imaging 2017: Physics of Medical Imaging

Y2 - 13 February 2017 through 16 February 2017

ER -

Direct measurement of Lubberts effect in CsI:Tl scintillators using single x-ray photon imaging

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Keywords

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