Ji-Koon Park

Quantitative evaluation of mercuric iodide thick film for x-ray imaging device

In this paper, we investigated electrical characteristics of the X-ray detector of mercuric iodide (HgI2) film fabricated by PIB(Particle-In-Binder) Method with thicknesses ranging from approximately 200μm to 240μm. In the present study, using I-V measurements, their electrical properties such as leakage current, X-ray sensitivity, and signal-to-noise ratio (SNR),were investigated. The results of our study can be useful in the future design and optimization of direct active-matrix flat-panel detectors (AMFPD) for various digital X-ray imaging modalities.

Effect of Annealing on the X-ray Detection Properties of Nano-sized Polycrystalline Lead Oxide Films

Polycrystalline lead oxide (PbO) film is an excellent candidate material for a direct conversion X-ray detector. However, the thick-bulky film tends to significantly reduce the charge collection efficiency for recombination process, and the effective number of electron-hole pairs is lower than that of thin film, because it is difficult to fabricate high-dense and thick PbO films. In this paper, we first synthesized nano-sized PbO particles that could be used in a novel high-efficiency flat panel X-ray detector using a simple solution/combustion method. Energy dispersive X-ray spectrometry, X-ray diffraction, and field emission scanning electron microscopy were used to analyze the component ratio and morphology of the PbO particles as a function of annealing temperature. Then, 150-µm-thick PbO films were deposited on glass substrates using a particle-in-binder method at room temperature. The influences of annealing before deposition on the X-ray detection characteristics of the PbO films were investigated in detail. The key parameters–the dark current, X-ray sensitivity, signal-to-noise ratio, and signal decay–were measured. The annealing conditions strongly affected the electrical properties of the PbO films. The X-ray sensitivity of films annealed in oxygen gas increased dramatically with increasing annealing temperatures up to 500 °C.

Experimental evaluation of a-Se flat-panel X-ray detector for digital radiography

In this paper, the evaluation of a selenium-based flat-panel digital X-ray detector is described. The prototype detector has a pixel pitch of 139 mum and a total active imaging area of 14 inches times 8.5 inches, making up a total of 3.9 million pixels. Several quantitative parameters have been devised that correlate with the abilities of imaging devices to perform clinical tasks. The concepts of MTF, NPS, and DQE have been well described and are very useful descriptors of resolution, noise, and signal-to-noise ratio transfer ability. Such parameters (sensitivity, leakage current, MTF, NPS, DQE) were examined to evaluate the performance of this system. The sensitivity of 4.82 nC/mR/cm2 was measured at 10 V/mum, while leakage current was measured at 270 pA/cm2. The measured MTF at 2 lp/mm was 40%, and the DQE at 1.5 lp/mm was 16%

Quantitative evaluation of mercuric iodide and selenium for X-ray imaging device

Analog film/screen systems have been replaced with digital X-ray imaging devices using direct conversion materials. In this paper, mercuric iodide (HgI/sub 2/) and amorphous selenium (a-Se) films were deposited through the particle-in-binder (PIB) and physical vapor deposition (PVD) methods, respectively. Using the MCNP 4C code, the interaction of X-ray photons in HgI/sub 2/ and a-Se bulk, their transport, and transmitted energy spectrum of continuous X-ray, with total absorbed energy were simulated. Using I-V measurements, their electrical properties, such as leakage current, X-ray sensitivity, and signal-to-noise ratio (SNR), were investigated. The results of our study can be useful in the future design and optimization of direct active-matrix flat-panel detectors (AMFPD) for various digital X-ray imaging modalities.

The Study on Design of Customized Radiation Protective Layer for Medical Radiation Dose Reduction

Abstract The fact is that in addition to an increase in social needs that must be managed systematically unnecessary exposure in the field of medical Recent important that the shield has emerged. However, products that are now in practical use, are not subdivided as compared to various medical radiology. Therefore, in the present study, we tried to present with the help of Monte Carlo simulation the structure of the shielding material that has been optimized. Simulated estimation result, the energy of the mammography for (30 kVp) spectrum, check the shielding rate of 90% or more 30μmPb, at 2 mmAl case of shielding material of a single, at design time of 1 mmAl and 0.03 mmPb a double shield structure it is determined that more efficient. Also, check the blocking rate of 90% or more 340μmPb, at 30 mmAl energy captured general in (80 kVp) spectra, it is considered that a double shield structure, design 1 mmAl and 0.3 mmPb is useful . These results, be used as basic material for the development of commercialization customized products for dose reduction is expected.

High-resolution phosphors as X-ray detectors for synchrotron radiation experiments

In this paper, the comparative performance of high-resolution phosphors using CCD(Charge Coupled Device) and CMOS(Complementary Metal Oxide Semiconductor) sensors for synchrotron radiation imaging is reported. Various phosphor films (ZnS [Cu, Al], ZnS [Ag, Al], Y/sub 2/O/sub 2/S [Tb], BiTiO/sub 3/) are deposited on glass substrates using printing techniques. The phosphor plates used were 5 /spl mu/m, 10 /spl mu/m, 15 /spl mu/m, and 20 /spl mu/m thick, respectively. To investigate the luminescent properties of phosphor plates, the excitation and photoluminescence spectra were measured. The 20 line-pair test pattern images were obtained and evaluated by calculating the modulation transfer function (MTF). From the experimental results, it was concluded that the thicker the phosphor plates, the better the luminescent efficiency of X-ray-induced light photons. The phosphor thickness, however, decreases the MTF due to light blurring. ZnS (Cu, Al) phosphor of 15 /spl mu/m thickness had a maximum value of 0.8 at 5 lp/mm.

A Study on the Insulation and Electrical Degradation Properties of Heat Resistance Epoxy Powder for Busduct

Reported here are results of the mechanical and electrical properties of both of intact and thermally degraded epoxy-coated copper busducts that are made by fluidized bed process. To elucidate and compare the properties mentioned above, electrical breakdown by thermal and water aging, v-t characteristic, bending test, impact test and cross cut test are carried out. Although the performance of electrical and mechanical properties are gradually decreased in increasing the severe conditions such as temperature, aging time, and so forth, sample C has a better performance in both mechanical and electrical properties.

The Implementation of Ultrasonic Hyperthermia Simulation Software

This To improve the efficiency of HIFU, the exact simulation of HIFU considering tissue characteristics is needed. In this study, the HIFU simulation program considering attenuation is developed and confirmed its usefulness by comparing with HIFU heating test in TMM phantom. It is expected that the developed simulation will be improved and widely used in the clinical field to improve the efficient of HIFU therapy.

Evaluation of the visual verification of linac light and radiation fields using film and a-Se based digital radiography system

Instructions for preparing papers for WC2006 Proceedings Series are presented. They are intended to guide the authors in preparing the electronic version of their paper. Only papers prepared according to these instructions will be published in the paper and online version of Proceedings. Provide an abstract of your paper no longer than 300 words.

Synthesis and Characterization of Y 2 O 3 :Eu Fine Particle

[ ] powder was synthesized using a solution-combustion method by dissolving and Eu in methyl-alcohol solution. Results from X-ray diffractometery (XRD), thermogravimetry (TG)-differential thermal analysis (DTA) show that crystallizes completely when the dry powder is sintered at . The investigated optical properties were the photoluminescence emission spectra, the excitation spectra and luminescence decay curve. Europium (Eu) concentration had no observable effect on the optical spectrum which depended on the emission intensity. The mean lifetime of synthesized phosphors was .