• Journal of the Korean Society of Radiology
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• v.12 no.7
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• pp.929-934
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• 2018

Studies for counting and detecting X-rays for the improvement of image quality and material analysis are active. In this work, the detector for X-ray photon counting was designed using Multi-pixel photon counter (MPPC) array and the detector characteristics were evaluated through simulation. Geant4 Application for Tomographic Emission (GATE) was used to obtain the position where the X-ray and the scintillation interacted, and this position was used as the light generation position of DETECT2000. 0.5 mm and 1 mm thick Gadolinium Aluminium Gallium Garnet (GAGG) scintillators were used and the light generated through a $4{\times}4$ array of MPPCs was acquired. The spatial resolution of the designed detector was evaluated by reconstructed image using the light signal acquired for each channel. We obtained images of more than 2 lp/mm in both 0.5 mm and 1 mm thick GAGG scintillation. When this detector is used in a X-ray system, a low-cost system capable of photon counting can be made.

• Journal of the Korean Society of Radiology
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• v.8 no.7
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• pp.455-459
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• 2014

We grew the $Li_6Gd(BO_3)_3:Ce^{3+}$ scintillator and determined the scintillation and thermoluminescence properties for X-rays. The emission spectrum of $Li_6Gd(BO_3)_3:Ce^{3+}$ is located in the range of 370~500 nm, peaking at 423 nm an 455 nm, due to the $4f{\rightarrow}5d$ transition of $Ce^{3+}$ ions. The fluorescence decay time of the crystal is composed three components. The fast component is 60 ns (25%), the intermediate component is 787 ns (29%) and the slow component is $5.9{\mu}s$ (46%) of the crystal. The after-glow is caused by the electron and hole traps in the crystal lattice. We determined physical parameters of the traps in the crystal. The thermoluminescence trap are composed two traps. The determined activation energy (E), kinetic order (m) and frequency factor (s) of the first trap are 0.65 eV, 1.01 and $6.9{\times}10^8s^{-1}$. And, the determined activation energy, kinetic order and frequency factor of the second trap are 0.96 eV, 1.79 and $3.1{\times}10^{12 }s^{-1}$, respectively.

• Progress in Medical Physics
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• v.19 no.4
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• pp.285-290
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• 2008

In this study, we have fabricated a one-dimensional fiber-optic dosimeter for electron beam therapy dosimetry. Each fiber-optic dosimeter has an organic scintillator with a plastic optical fiber and it is embedded and arrayed in the plastic phantom to measure one-dimensional high energy electron beam profile of clinical linear accelerator. The scintillating lights generated from each sensor probe are guided by plastic optical fibers to the multi-channel photodiode amplifier system. We have measured one-dimensional electron beam profiles in a PMMA phantom according to different field sizes and energies of electron beam. Also, the isodose and three-dimensional percent depth dose curves in a PMMA phantom are obtained using a one-dimensional fiber-optic dosimeter with different electron beam energies.

• Progress in Medical Physics
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• v.13 no.1
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• pp.44-50
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• 2002

CsI(T1) single crystal was grown in a Bridgman growing apparatus, which has the diameter of 11 mm and the mole ratio of 0.001 mol%. Radiation sensors were made with CsITl)crystal and two photodiodes, and measured spectroscopic characteristics and linearity for gamma-ray and X-ray. The energy resolution of CsI(T1) radiation sensor has been measured with $^{22}$ Na, $^{137}$ Cs and $^{60}$ Co gamma standard sources. Also output linearity of CsITl) sensor was measured for diagnostic radiation region. The energy resolutions of CsI(T1) radiation sensor for 0.511MeV gamma-ray from Na-22 source, 0.662MeV from Cs-137 source, and 1.17MeV and 1.332MeV from Co-60 source were 13.2%, 8.3%, 6.7%, and 5.1% respectively. Also the output linearity up to 80mAs current for 60kVp, 80kvp, 100kVp, 120kVp tube voltages has been studied.

• Proceedings of the Membrane Society of Korea Conference
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• 2004.11a
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• pp.135-138
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• 2004

• Applied Chemistry for Engineering
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• v.17 no.6
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• pp.604-608
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• 2006

Polymer composites for measuring the radioactive contamination are prepared by coating ZnS(Ag) powders as a scintillator on polysulfone base layer. The composites consist of the active layer for a scintillation reaction with radioactive wastes and the transparent support layer for transmittance of light photons emitted by scintillation in the active layer. The binding of the active layer, including ZnS(Ag), on the support layer is proceeded via coating with polysulfone as a binder, without any extra adhesive. The coating was obtained by either casting via a Doctor Blade as applicator or screen printing. The prepared composites feature a monolithic structure, resulting in the complete adhesion between two layers. The composite prepared by the casting technique using an applicator holds a good detection efficiency in measuring the alpha radionuclide, but its structure becomes fragile because of warping in morphology. On the contrary, the composite prepared by the screen printing shows a good detection capacity as well as a good stability in a mechanical shape.

• Proceedings of the Korean Radioactive Waste Society Conference
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• 2010.10a
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• pp.33-34
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• 2010

• Journal of the Korea Academia-Industrial cooperation Society
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• v.12 no.2
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• pp.600-604
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• 2011

In this paper, the scintillation properties of $LaCl_3:Eu^{2+}$ crystal were investigated as new scintillator. This scintillation material was grown by a Czochralski method. $LaCl_3:Eu^{2+}$ was determined to have a hexagonal $P_63$/m space group with cell parameters a = b = $7.48{\AA}$, c = $4.37{\AA}$. Under 335 nm UV excitation, the crystal shows a broad emission band between 370 nm and 640 nm wavelength range, peaking at 430 nm. At room temperature, the crystal exhibits one exponential decay time component. The component of scintillation time profile of the crystal emission decays with a $2.82{\pm}0.72{\mu}s$ time constant. The energy resolution of the crystal was measured to be 8.8% (FWHM) for $^{137}Cs$ 662 keV ${\gamma}$-rays.

• Journal of Energy Engineering
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• v.13 no.2
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• pp.93-100
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• 2004

The smear media possible to sampling and radiation detection was prepared and evaluated for the surface contamination using indirect method. The films were made by impregnating Cerium Activated Yttrium Silicate (CAYS) in a polysulfone membrane. The membranes used solution as a dimethylformamide (DMF) and methylene chloride (MC), polysulfone as a polymer matrix and CAYS as a inorganic scintillator. The proximity membranes were prepared with single- and double-layered structure. The solidified methods were immersion to the nonsolvent bath such at water and ethanol and solvent evaporation. The measurement of the photon produced by interaction with radiation and inorganic scintillator used a photomultiflier tube (PMT), amplifier, and counter. In the comparison with the low background alpha/beta counter, the counter rate using inorganic scintillator proximity membrane for the $\^$14/C surface contamination was about 50%. Also. the $^3$H counting results revealed that the prepared membranes were efficient to monitor the surface contaminated with the low energy be-ray emitter nuclides.

• Journal of radiological science and technology
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• v.28 no.1
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• pp.9-12
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• 2005

In this study, film type radiation sensor tips are fabricated for remote sensing of X or g-ray with inorganic scintillators and plastic optical fiber. The visible range of light from the inorganic scintillator that is generated by X and g-ray is guided by the plastic optical fiber and is measured by optical detector and power-meter. It is expected that the fiber-optic radiation sensor which is possible to be developed based on this study is used for remote, fast and exact sensing of X or g-ray because of its characteristics such as very small size, light weight and no interference to electromagnetic fields.