• Journal of radiological science and technology
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• v.30 no.4
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• pp.349-356
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• 2007

Conclusions below are drawn after survey date from 1,969 samplers of mammography and 1,531 breast ultrasound for 10 months, from 1 July 2006 to 30 April 2007. 1. Ages between 40 and 50 of samplers take the largest part of age distribution, and 68.57% of mammography and 71.32% of samplers are fallen under the category. 2. Samplers judged by diseased patients are 31.95% samplers of mammography and 45.79% samplers of breast ultrasound. 3. Age distributions of diseased patients were from 30 to 60 in mammography, 30 to 50 in breast ultrasound. 4. Breast ultrasound shows little difference between left side and right side of diseased part, but mammography shows significant diseased part in both sides. 5. As a result of reading examination, there is higher probability of detection in order of Calcification, Nodular, Mass in mammography. And Cyst, Nodular, Mass in breast ultrasound. 6. As a reading examinations, probability of judging a certain disease in high in mammography, but breast ultrasound shows 1 or 2 kinds of disease.

• Journal of the Korean Society of Radiology
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• v.3 no.1
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• pp.17-21
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• 2009

The Recently, large area matrix-addressed image detectors are investigated for X-ray imaging with medical diagnostic and other applications. In this paper, a new flat panel gas detector for diagnostic X-ray imaging is proposed, and its characteristics are investigated. The research of flat panel gas detector is not exist at all. Because of difficulty to inject gas against to atmospheric pressure. So almost gas detector made by chamber shape. We made flat panel sample by display technique. (ex: PDP, Fed, etc.) The experimental measurements, the transparent electrodes, dielectric layer, and the MgO protection layer were formed in front glass. And, the X-ray phosphor layer and address electrodes are formed in the rare glass. The dark current, the x-ray sensitivity and linearity as a function of electric field were measured to investigate the electrical properties. From the results, the stabilized dark current density and the significant x-ray sensitivity were obtained. And the good linearity as a function of exposure dose was showed in wide diagnostic energy range. These results means that the passive matrix-addressed flat panel gas detector can be used for digital x-ray imaging.

• Journal of the Mineralogical Society of Korea
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• v.16 no.1
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• pp.65-73
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• 2003

In this study we have derived the two correction methods of hydrogen bonding distance. In case of the intermediate or long hydrogen bond(＞2.5 $\AA$), hydrogen bonding distances can be corrected by using the function d(O-H)=exp((2.173-d(O…O))/0.138)+0.958 obtained by least- squares fit to the data from the neutron diffraction at low temperatures. The valence-least-squares method is effective for the distance correction of very short hydrogen bond(<2.5 $\AA$). The distance correction is necessary for the long intermolecular hydrogen bond obtained from X-ray diffraction analysis.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.10 no.6
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• pp.666-673
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• 1998

Solubilities (LiBr+$CaC1_2$) in water were measured at temperatures form 267.51 to 306.17K for $CaC1_2$ (LiBr+$CaC1_2$)=0.24 by mole. Experimental data were correlated with polynomial equations. Average absolute deviations between the measured and calculated values were 0.31% at concentration smaller than 60wt% and 0.41% at concentration larger than 60wt%, respectively. Vapor pressures were measured at temperatures from 296.75 to 436.75K and concentrations from 40 to 70wt%. Vapor pressure data were fitted to a Antoine-type equation and average absolute deviation was 2.98%. The P-T-X chart and H-T-X chart of $H_2O$/(LiBr+$CaC1_2$) system were constructed by using the correlation equations of solubility, vaper pressure, and heat capacity. The P-T-X chart indicates that $H_2O$/(LiBr+$CaC1_2$) system has potential as a possible working fluid for air-cooled absorption chillers.

• Progress in Medical Physics
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• v.2 no.1
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• pp.29-35
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• 1991

For accureate treatment planning, new models of dose calculations are being developed which require the knowledge of the energy spectra and angular distributions of the X-rays incident on the surface of the material. In this present study, we applied the Monte Carlo methods to the systematic analysis of the spectra distribution of X-ray beams produced by medical linear accelerator. As expected, the spectra become softer as the distance is farther from the central axis. also, its influenced by the geometrical dffect of head system.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.11 no.9
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• pp.3517-3523
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• 2010

Single exposure dual X-ray imaging can be used to separate soft and dense-material images for medical and industrial applications. This study keep focusing baggage inspection system(BIS) specifically. New detector modules for single exposure dual X-ray imaging are consisted of low energy detector (LED) and high energy detector (HED). First, the optimized thickness of copper filter coupled HED to separate low energy and high energy was simulated by the given X-ray energy (140 kVp, 1 mA) using Monte Carlo simulation codes, MCNPX. So as a result of simulation, the copper filter thickness is 0.7 mm. For the design of PIN photodiode, ATLAS device simulation tool was used. 16 channels PIN photodiode of 1.5 mm ${\times}$ 3.2 mm for Dual X-ray imaging detector was fabricated in the process of ETRI. And its dark current and quantum efficiency, terminal capacitance were measured. It was proven that the Lanex Fast B coupled HED were a sufficient candidate to replace the CsI(Tl) commerced in dual X-ray system, since these give a strong signal, overcoming system noise. Finally dual X-ray image was acquired through correction of the LED X-ray Image and the HED X-ray Image.

• Korean Journal of Optics and Photonics
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• v.19 no.4
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• pp.249-254
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• 2008

We developed a new x-ray image sensor utilizing a reflection-mode liquid crystal panel as its sensitive element, and tested its functionality by using it to obtain an x-ray image of a printed circuit board. In the liquid crystal x-ray image sensors hitherto reported, the liquid crystal layer is in direct contact with the photoconductive film which is deposited on a glass substrate. In the fabrication of the new x-ray image sensor, a liquid crystal panel is fabricated in the first step by using a pair of glass plates of a few centimeters thicknrss. Then one of the glass substrates is ground until its thickness is reduced to about $60\;{\mu}m$. After polishing the glass plate, dielectric films for high reflectance at 630 nm, a film of amorphous selenium for photoconduction, and a transparent conductive film for electrode are deposited in sequence. The new x-ray image sensor has several merits: primarily, fabrication of a large area sensor is more easily compared with the old fashioned x-ray image sensors. Since the reflection type liquid crystal panel has a very steep response curve, the new x-ray sensor has much more sensitivity to x-rays compared with the conventional x-ray area sensor, and the radiation dosage can be reduced down to less then 20%. By combining the new x-ray sensor with CCD camera technology, real-time x-ray images can be easily captured. We report the structure, fabrication process and characteristics of the new x-ray image sensor.

• The Transactions of the Korean Institute of Power Electronics
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• v.8 no.2
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• pp.192-198
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• 2003

Recently, the Inverter type X-ray generator is rapidly replacing the conventional single-phase or three-phase X-ray generator, it has several merits of space-saving: high accuracy and reproducibility. This paper presents a 40kw(12kV, 80mA) high tension generator system for diagnosis X-ray. The control circuit and design consideration of the proposed high tension power supply are given. Issues in the design of high voltage isolating transformer are discussed. Experimental results are presented to verify the performance of the designed power supply for varying load conditions. 1'he proposed apparatus has several advantages, e. g., the fast rising time of tube voltage, accuracy and reduced component size etc.

• Journal of the Korean Society for Nondestructive Testing
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• v.16 no.1
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• pp.10-18
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• 1996

This study verified the relationship between fracture mechanics parameters and X-ray parameters for normalized SS41 steel with homogeneous crystal structure and M.E.F. dual phase steel(martensite encapsulated islands of ferrite). The fatigue crack propagation test were carried out and X-ray diffraction technique was applied to fatigue fractured surface. The change in X-ray parameters(residual stress, half-value breadth) according to the depth of fatigue fractured surface were investigated. The depth of maximum plastic zone, $w_y$, were determined on the basis of the distribution of the half-value breadth for normalized SS41 steel and that of the residual stress for M.E.F. dual phase steel. $K_{max}$ could be estimated by the measurement of $w_y$.

• Journal of Radiation Protection and Research
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• v.24 no.4
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• pp.195-203
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• 1999

It is difficult to determine dosimetric characteristics for small field photon beams since such small fields do not achieve complete lateral electronic equilibrium and have steep dose gradients. Dosimetric characteristics of small field 4, 6, and 10 MeV photon beams have been measured in water with a diamond detector and compared to measurements using small volume cylindrical and plane parallel ionization chambers. Percent depth dose (PDD) and beam profiles for 6 and 10 MeV photon beams were measured with diamond detector and cylindrical ion chamber for small fields ranging from $1{\times}1\;to\;4{\times}4cm^2$. Total scatter factors($S_{c,p}$) for 4, 6, and 10 MeV photon beams were measured with diamond detector, cylindrical and plane parallel ion chambers for small fields ranging from $1{\times}1\;to\;4{\times}4cm^2$. The $S_{c,p}$ factors obtained with three detectors for 4, 6, and 10 MeV photon beams agreed well ($\pm1.2%$) for field sizes greater than $2{\times}2,\;2.5{\times}2.5,\;and\;3{\times}3\;cm^2$, respectively. For smaller field sizes, the cylindrical and plane parallel ionization chambers measure a smaller $S_{c,p}$ factor, as a result of the steep dose gradients across their sensitive volumes. The PDD values obtained with diamond detector and cylindrical ionization chamber for 6 and 10MeV photon beams agreed well ($\pm1.5%$) for field sizes greater than $4{\times}4\;cm^2$. For smaller field sizes, diamond detector produced a depth-dose curve which had a significantly shallower falloff than that obtained from the measurements of relative depth-dose with a cylindrical ionization chamber. For the measurements of beam profiles, a distortion in terms of broadened penumbra was observed with a cylindrical ionization chamber since diamond detector exhibited higher spatial resolution. The diamond detector with small sensitive volume, near water equivalent, and high spatial resolution is suitable detector compared to ionization chambers for the measurements of small field photon beams.