• Journal of the Korean Society of Radiology
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• v.13 no.1
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• pp.111-118
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• 2019

Chest digital tomosynthesis has become a practical imaging modality because it can solve the problem of anatomy overlapping in conventional chest radiography. However, because of both limited scan angle and finite-size detector, a portion of chest cannot be represented in some or all of the projection. These bring a discontinuity in intensity across the field of view boundaries in the reconstructed slices, which we refer to as the truncation artifacts. The purpose of this study was to reduce truncation artifacts using a weighted normalization approach and to investigate the performance of this approach for our prototype chest digital tomosynthesis system. The system source-to-image distance was 1100 mm, and the center of rotation of X-ray source was located on 100 mm above the detector surface. After obtaining 41 projection views with ${\pm}20^{\circ}$ degrees, tomosynthesis slices were reconstructed with the filtered back projection algorithm. For quantitative evaluation, peak signal to noise ratio and structure similarity index values were evaluated after reconstructing reference image using simulation, and mean value of specific direction values was evaluated using real data. Simulation results showed that the peak signal to noise ratio and structure similarity index was improved respectively. In the case of the experimental results showed that the effect of artifact in the mean value of specific direction of the reconstructed image was reduced. In conclusion, the weighted normalization method improves the quality of image by reducing truncation artifacts. These results suggested that weighted normalization method could improve the image quality of chest digital tomosynthesis.

• The Journal of Korean Society for Radiation Therapy
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• v.25 no.2
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• pp.115-121
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• 2013

Purpose: Latest linear accelerator and the introduction of new measurement equipment to the agency that the introduction of this equipment in the future, by analyzing the process of confirming the usefulness of the preparation process for applying it in the clinical causes some problems, should be helpful. Materials and Methods: All measurements TrueBEAM STX (Varian, USA) was used, and a file specific to each energy, irradiation conditions, the dose distribution was calculated using a computerized treatment planning equipment (Eclipse ver 10.0.39, Varian, USA). Measuring performance and cause errors in MapCHECK 2 were analyzed and measured against. In order to verify the performance of the MapCHECK 2, 6X, 6X-FFF, 10X, 10X-FFF, 15X field size $10{\times}10$ cm, gantry $0^{\circ}$, $180^{\circ}$ direction was measured by the energy. IGRT couch of the CT values affect the measurements in order to confirm, CT number values : -800 (Carbon) & -950 (COUCH in the air), -100 & 6X-950 in the state for FFF, 15X of the energy field sizes $10{\times}10$, gantry $180^{\circ}$, $135^{\circ}$, $275^{\circ}$ directionwas measured at, MapPHAN allocated to confirm the value of HU were compared, using the treatment planning computer for, Measurement error problem by the sharp edges MapPHAN Learn gantry direction MapPHAN of dependence was measured in three ways. GANTRY $90^{\circ}$, $270^{\circ}$ in the direction of the vertically erected settings 6X-FFF, 15X respectively, and Setting the state established as a horizontal field sizes $10{\times}10$, $90^{\circ}$, $45^{\circ}$, $315^{\circ}$, $270^{\circ}$ of in the direction of the energy-6X-FFF, 15X, respectively, were measured. Without intensity modulated beam of the third open arc were investigated. Results: Of basic performance MapCHECK confirm the attenuation measured by Couch, measured from the measured HU values that are assigned to the MAP-PHAN, check for calculation accuracy for the angled edge of the MapPHAN all come in a range of valid measurement errors do not affect the could see. three ways for the Gantry direction dependence, the first of the meter built into the value of the Gantry $270^{\circ}$ (relative $0^{\circ}$), $90^{\circ}$ (relative $180^{\circ}$), 6X-FFF, 15X from each -1.51, 0.83% and -0.63, -0.22% was not affected by the AP/PA direction represented. Setting the meter horizontally Gantry $90^{\circ}$, $270^{\circ}$ from the couch, Energy 6X-FFF 4.37, 2.84%, 15X, -9.63, -13.32% the difference. By-side direction measurements MapPHAN in value is not within the valid range can not, because that could be confirmed as gamma pass rate 3% of the value is greater than the value shown. You can check the Open Arc 6X-FFF, 15X energy, field size $10{\times}10$ cm $360^{\circ}$ rotation of the dose distribution in the state to look at nearly 90% pass rate to emerge. Conclusion: Based on the above results, the MapPHAN gantry direction dependence by side in the direction of the beam relative dose distribution suitable for measuring the gamma value, but accurate measurement of the absolute dose can not be considered is. this paper, a more accurate treatment plan in order to confirm, Reduce the tolerance for VMAT, such as lateral rotation investigation in order to measure accurate absolute isodose using a combination of IMF (Isocentric Mounting Fixture) MapCHEK 2, will be able to minimize the impact due to the angular dependence.

• Korean Journal of Food Science and Technology
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• v.44 no.5
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• pp.532-539
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• 2012

Electron spin resonance (ESR) spectroscopy of gamma-irradiated fresh broccoli and kimchi cabbage was conducted to identify their irradiation history. Different pretreatments, such as freeze-drying (FD), oven-drying (OD), alcoholic-drying (ALD), and water-washing and alcoholic-drying (WAD) were used to lower the moisture contents of the samples prior to ESR analysis. The non-irradiated samples exhibited a single central signal ($g_0$=2.0007) with clear effect of $Mn^{2+}$, especially in kimchi cabbage. Upon irradiation, there was an increase in the intensity of the central signal, and two side peaks, mutually spaced at 6 mT, were also observed. These side peaks with $g_1$ (left)=2.023 and $g_2$ (right)=1.985 were attributed to radiation-induced cellulose radicals. Leaf and stem in broccoli, and root and stem in kimchi cabbage provided good ESR signal responses upon irradiation. The signal noise was reduced in case of ALD and WAD pretreatments, particularly due to $Mn^{2+}$ signals. The ALD treatment was found most feasible to detect the improved ESR spectra in the irradiated samples.

• Journal of the Korean Chemical Society
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• v.38 no.11
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• pp.827-832
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• 1994

The crystal structure of bis(N-methylphenazinium) bis(oxalato)palladate(II) has been determined by X-ray crystallography. Crystal data: ((C_{13}H_{11}N_2)_2[Pd(C_2O_4)_2]) $M_w$ = 672.93, Triclinic, Space Group P1 (No = 2), a = 7.616(8), b = 9.842(3), c = $20.335(7)\AA$, $\alpha$ = 103.53(3), $\beta$ = 90.00(5), $\gamma$ = $112.38(5)^{\circ}$, Z = 2, $V = 1363(2){\AA}^3\;D_c = 1.639\;gcm^{-3},\;{\mu} = 7.3\;cm^{-1},\;F(000) = 680.0$. The intensity data were collected with $Mo-K\alpha$ radiation (${\lambda}$= 0.7107\;\AA)$ on an automatic four-circle diffractometer with a graphite monochromater. The structure was solved by Patterson method and refined by full matrix least-square methods using Killean & Lawrence weights. The final R and S values were $R = 0.069,\;R_w = 0.050,\;R_{all} = 0.069$ and S = 5.45 for 3120 observed reflections. Both cation and anion complexes are essentially planar and have dihedral angles of 6.3(6) and $57.06(6)^{\circ}$ between their planes. The planar complex anions are sandwiched between slightly bent cations. The interplanar separations of two triads are 3.328 and 3.463 $\AA$, respectively. The triads are stacked along b-axis, but their orientations are different based on dihedral angle $59.08(9)^{\circ}$ of two complex anions.

• Journal of the Korean Society of Radiology
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• v.4 no.4
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• pp.25-28
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• 2010

In this paper, the fabrication and feasibility study of clinical application with euripium doped gadollium oxide ($Gd_2O_3$:Eu) nano phosphor derived by low-temperature solution combustion method. From the fabricated phosphor, the photoluminescent characteristic and linearity as a function of phosphor film thickness were investigated to evaluate x-ray converstion properties. From the experimental results, the luminescent intensity was $2945pC/cm^2$-mR at $270{\mu}m$ $Gd_2O_3$:Eu film and this value is higher 1.2 time the conventional bulk phosphor, which is possible to imaging acquisition. And good linearity was shown at x-ray exposure range for clinical diagnostic application.

• Journal of the Korean Vacuum Society
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• v.22 no.6
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• pp.341-347
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• 2013

The n-type and p-type silicon samples were exposed by 40.0, 3.98 MeV proton beams ranging between 0 to $20.0{\times}10^{13}protons/cm^2$. Coincidence Doppler Broadening Positron Annihilation Spectroscopy (CDBPAS) were applied to study of defect characteristics of p type and n type silicon samples. In this investigation the numerical analysis of the spectra was employed to the determination of the shape parameter, S, defined as the ratio between the amount of counts in a central portion of the gamma spectrum and the total counts of whole gamma spectrum. The S-parameter values strongly depend on the irradiated proton beam that indicated the defects generate more, rather than the energy intensity. 40 MeV irradiated proton beam in the n-type silicon at $20.0{\times}10^{13}protons/cm^2$ was larger defects than 3.98 MeV irradiated proton beam. It was analysis between the proton irradiation beams and the proton intensities of the irradiation. Because of the Bragg peak, SRIM results shows mainly in a certain depth of the sample to form the defect by the proton irradiation, rather than the defects to appear for the entire sample.

• Progress in Medical Physics
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• v.23 no.3
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• pp.127-137
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• 2012

A conversing beam is firstly designed for radiosurgery by a neurosugern Lars Leksell in 1949 with orthogonal x-rays tube moving through horizontal moving arc to focusing the beam at target center. After 2 decades he composits 201 source of the Co-60 for gamma knife which beams focused at locus. Sveral linac-based stereotactic radiosurgery using the circular collimated beam which size range for 0.4~4.0 cm in a diameter by non-coplanar multiarc have been developed over the decades. The irregular lesions can be treated by superimposing with several spherical shots of radiation over the tumour volume. Linac based techniques include the use of between 4 and 11 non-co-planar arcs and a dynamic rotation technique and use photon beam energies in the range of 6~10 MV. Reviews of the characteristics of several treatment techniques can be found in the literature (Podgorsak 1989, Schell 1991). More in recent, static conformal beams defined by custom shaped collimators or a mini- or micro-multileaf collimator (mMLC) have been used in SRS. Finally, in the last few years, intensity-modulated mMLC SRS has also been introduced. Today, many commercial and in-house SRS programs have also introduced non-invasive immobilization systems include the cyberknife and tomotherapy and proton beam. This document will be compared the characteristics of dose distribution of radiosurgery as introduced gamma knife, BrainLab include photon knife in-house SRS program and cyberknife in currently wide used for a cranial SRS.

• Investigative Magnetic Resonance Imaging
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• v.10 no.2
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• pp.89-97
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• 2006

Purpose : To evaluate MR image qualities we developed a new MRI phantom with the fixation structures necessary to position it into coil firmly. Materials and methods : We designed MRI phantom for eight evaluation items such as slice thickness accuracy, high contrast spatial resolution, low contrast object detectability, geometry accuracy, slice position accuracy, image intensity uniformity, percent signal ghosting and signal to noise ratio. For the positioning of phantom at coils, the fixation structures were set up on the surface of phantom. Six different MRI units were used for test the possibility for the clinical application and their image qualities were evaluated. Results : We acquired appropriate MR image qualities enough for the evaluation on all used MR units and confirmed that their evaluations were within reliable values compared to real ones for some items. The positioning of our phantom into head coils with fixation structures worked well for proper imaging. Conclusion : We found that our prototype of MRI phantom had the possibility of clinical application for MR image quality assessment.

• Korean Journal of Agricultural and Forest Meteorology
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• v.17 no.4
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• pp.340-347
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• 2015

This study was conducted to analyze the relationship between climate factors and fruit characteristics of 'Sangjudungsi' persimmon (Diospyros kaki THUNB) has been mainly cultivated in Sangju of Korea. We has been surveyed the yield and fruit characteristics such as fruit weight and soluble solids of 'Sangjudungsi' persimmon from 2010 to 2015 for five years. Also, as major meteorological factor, mean air temperature, cumulative temperature and days, the data of sunshine duration, diurnal range, and rainfall were collected from Sangju Regional Meteorological Administration. As result of that, the annual variation of fruit weight was affected by sunshine duration for April and October related starting point of fruit weight increase. The content of soluble solids was affected by sunshine duration for April and October similarly with fruit weight and was negatively correlated with the number of days with precipitation in the year. These results indicate the characteristics related to fruit quality like the above were affected by the sunshine duration and precipitation which is critical factor for the intensity of radiation during rapid growth period (April and October). Fruit number and yield per tree was commonly affected by mean air temperature of April and cumulative temperature days of October. These results also indicate that temperature for period of rapid growth stage of persimmon may have an important role in the fruit number and yield per tree.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.12 no.1
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• pp.413-419
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• 2011

Diagnosis X-ray equipment localized at 1950's but it is developed suddenly at 1960's with demand together. Manufacture of Diagnostic X-ray equipment is controled by the KS regulation and the Ministry of Health and Welfare because of hazardous element etc. exposure by radiation. Most of diagnostic X-ray equipment ware single phase and three phase full-wave rectification but from 1980's it transforms it was exchanged in inverter type X-ray equipment. Inverter type X-ray equipment produces approximately 50~80% more average photon intensity then single phase full-wave rectification and the accuracy is high. But from a clinic it dose not use because expensive therefor the efficiency improvement of single phase full-wave rectification is necessary. We produced single phase full-wave rectification X-ray equipment control unit, high tension transformer, filament heating transformer, rectification circuit, high tension cable and others and evaluated efficiency, in result which is excellent compare with Rule of Safety Management and KS regulation.