• Journal of the Korean Society of Radiology
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• v.14 no.1
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• pp.1-6
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• 2020

In this study, it was intended to replace the existing plane parallel ionization chamber, which requires cross-calibration in electron beam treatment. The semiconductor compounds HgI₂ was fabricated as detector, and the characteristics of HgI₂ detector for the 6, 9 and 12 MeV electron beam was analyzed in the linear accelerator. It was also intended to evaluate the possibility of substitution with existing detectors and their applicability as electron beam dosimetry and to use them as a basic study of the development of electronic beam dosimeter. As a result of reproducibility, RSD was 0.4246%, 0.5054%, and 0.8640% at 6, 9, and 12 MeV energy, respectively, indicating that the output signal was stable. As a result of the linearity, the R² was 0.9999 at 6 MeV, 0.9996 at 9 MeV, and 0.9997 at 12 MeV showed that the output signal is proportional to HgI₂ as the dose is increased. The HgI₂ detector of this study is highly applicable to electron beam measurement, and it may be used as a basic research on electron beam detection.

• Journal of Pharmaceutical Investigation
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• v.40 no.2
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• pp.101-107
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• 2010

A rapid and sensitive reversed-phase high performance liquid chromatography (HPLC) method was developed for the determination of N-(-4-Chlorophenyl)-6-hydroxy-7-methoxy-2-chromanecarboxamide (KAL-1120), a novel anti-inflammation agent, in the rat plasma. The method was applied to analyze the compound in the biological fluids such as bile, urine and tissue homogenates. After liquid-liquid extraction, the compound was analyzed on an HPLC system with ultraviolet detection at 275 nm. HPLC was carried out using reversed-phase isocratic elution with a $C_{18}$ column, a mobile phase of a mixture of acetonitril (40 v/v%) at a flow rate of 1.0 mL/min. The chromatograms showed good resolution and sensitivity and no interference of plasma. The calibration curve for the drug in plasma was linear over the concentration range of 0.05-50 ${\mu}g$/mL. The intra- and inter-day assay accuracies of this method ranged from 0.06% to 9.33% of normal values and the precision did not exceed 6.28% of relative standard deviation. The plasma concentration of KAL-1120 decreased to below the quantifiable limit at 1.5 hr after the i.v. bolus administration of 2-10 mg/kg to rats ($t_{1/2,({\alpha})}$ and $t_{1/2,({\beta})$ of 2.15 and 26.7 min at a dose of 2 mg/kg, 3.91 and 33.0 min at a dose of 10 mg/kg, respectively). The steady-state volume of distribution ($V_{dss}$) and the total body clearance ($CL_t$) were not significantly altered in rats given doses from 2 to 10 mg/kg. Of the various tissues tested, KAL-1120 was mainly distributed in the lung and heart after i.v. bolus administration. KAL-1120 was detected in the bile by 30 min after its i.v. bolus administration. However, the concentration in the urine after i.v. bolus administration became too low to measure, suggesting that KAL-1120 is mostly excreted in the bile. In conclusion, this analytical method was suitable for the preclinical pharmacokinetic studies of KAL-1120 in rats.

• Progress in Medical Physics
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• v.15 no.4
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• pp.215-219
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• 2004

Due to their excellence for the high-energy therapy range of photon beams, researchers show increasing interest in applying MOSFET dosimeters to low- and medium-energy applications. In this energy range, however, MOSFET dosimeter is complicated by the fact that the interaction probability of photons shows significant dependence on the atomic number, Z, due to photoelectric effect. The objective of this study is to develop a very detailed 3-dimensional Monte Carlo simulation model of a MOSFET dosimeter for radiological characterizations and calibrations. The sensitive volume of the High-Sensitivity MOSFET dosimeter is very thin (1 ${\mu}{\textrm}{m}$) and the standard MCNP tallies do not accurately determine absorbed dose to the sensitive volume. Therefore, we need to score the energy deposition directly from electrons. The developed model was then used to study various radiological characteristics of the MOSFET dosimeter. the energy dependence was quantified for the energy range 15 keV to 6 MeV; finding maximum dependence of 6.6 at about 40 keV. A commercial computer code, Sabrina, was used to read the particle track information from an MCNP simulation and count the tracks of simulated electrons. The MOSFET dosimeter estimated the calibration factor by 1.16 when the dosimeter was at 15 cm depth in tissue phantom for 662 keV incident photons. Our results showed that the MOSFET dosimeter estimated by 1.11 for 1.25 MeV photons for the same condition.

• Journal of the Korean Society of Radiology
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• v.13 no.6
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• pp.831-840
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• 2019

The X-ray detector by liquid crystal with front light was proposed and verified by a X-ray image. The proposed detector utilizes the visible light instead of the electric signal by transistor. Therefore, it shows low noise and can be fabricated at low cost. The liquid crystal detector uses the orientation change of the liquid crystal molecule by conductivity change of the photoconductive layer. We can get the X-ray image from the transmitted light through the liquid crystal. The X-ray dose was calibrated from the measured transmittance of the visible light after comparison to the reference transmittance curve of the liquid crystal. The amorphous Se was used for photo con ducting layer and parylene was used for the liquid crystal alignment instead of the conventional alignment layer which needs high-temperature process over 200℃. The proposed X-ray detector can decrease the X-ray dose by high sensitivity which was verified by simulation. After the fabrication of the X-ray detector, the X-ray image was obtained as a function of the bias voltage to the liquid crystal. 10 lines/mm resolution was obtained from the line pattern and we will apply it to the 17inch diagonal liquid crystal X-ray detector with 3π retardation.

• Progress in Medical Physics
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• v.34 no.1
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• pp.1-9
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• 2023

Purpose: Although ionization chambers are widely used to measure beam commissioning data, point-by-point measurements of all the profiles with various field size and depths are time-consuming tasks. As an alternative, we investigated the feasibility of a linear diode array for commissioning a treatment planning system. Methods: The beam data of a Varian TrueBeam^® radiotherapy system at 6 and 10 MV with/without a flattening filter were measured for commissioning of an Eclipse Analytical Anisotropic Algorithm (AAA) ver.15.6. All of the necessary beam data were measured using an IBA CC13 ionization chamber and validated against Varian "Golden Beam" data. After validation, the measured CC13 profiles were used for commissioning the Eclipse AAA (AAA_CC13). In addition, an IBA LDA-99SC linear diode array detector was used to measure all of the beam profiles and for commissioning a separate model (AAA_LDA99). Finally, the AAA_CC13 and AAA_LDA99 dose calculations for each of the 10 clinical plans were compared. Results: The agreement of the CC13 profiles with the Varian Golden Beam data was confirmed within 1% except in the penumbral region, where ≤2% of a discrepancy related to machine-specific jaw calibration was observed. Since the volume was larger for the CC13 chamber than for the LDA-99SC chamber, the penumbra widths were larger in the CC13 profiles, resulting in ≤5% differences. However, after beam modeling, the penumbral widths agreed within 0.1 mm. Finally the AAA_LDA99 and AAA_CC13 dose distributions agreed within 1% for all voxels inside the body for the 10 clinical plans. Conclusions: In conclusion, the LDA-99SC diode array detector was found to be accurate and efficient for measuring photon beam profiles to commission treatment planning systems.

• Journal of Society of Preventive Korean Medicine
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• v.17 no.3
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• pp.165-176
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• 2013

Objective : The purpose of this study was to establish the simultaneous analysis for six compounds in Gumiganghwal-tang (GMGHT, Jiuweiqianghuo-tang) and to investigate the anti-atherosclerotic effects of GMGHT in vitro. Methods : The column for separation of six compounds was used Luna $C_{18}$ column and maintained at $40^{\circ}C$. The mobile phase for gradient elution consisted of two solvent systems, 1.0% acetic acid in water and 1.0% acetic acid in acetonitrile. The analysis was carried out at a flow rate of 1.0 mL/min with pothodiode array (PDA) detection at 254, 280, and 320 nm. The injection volume was 10 ${\mu}L$. The antioxidant activities of GMGHT were evaluated by measuring free radical scavenging activities on 2,2'-Azinobis-3-ethyl-benzothiazoline-6-sulfonic acid (ABTS) and 1-1-diphenyl-2-picrylhydrazyl (DPPH). The inhibitory effects on low-density lipoprotein (LDL) oxidation were evaluated by the formation of thiobarbituric acid relative substances (TBARS), relative electrophoretic mobility (REM), and fragmentation of apolipoprotein B (ApoB)-100. Results : Calibration curves were acquired with $r^2{\geq}0.9998$. The contents of liquiritin, ferulic acid, baicalin, baicalein, glycyrrhizin, and wogonin in GMGHT were 1.784, 1.693, 37.899, 0.258, 1.869, and 0.034 mg/g, respectively. The GMGHT showed the radical scavenging activity in a dose-dependent manner. The concentration required for 50% reduction ($RC_{50}$) against ABTS and DPPH radicals were 72.51 ${\mu}g/mL$ and 128.49 ${\mu}g/mL$. Furthermore, GMGHT reduced the oxidation properties of LDL induced by $CuSO_4$. Conclusion : HPLC-PDA is considered as an available and convenient method for quality control and standardization of GMGH and GMGHT has potentials on anti-atherosclerosis by anti-oxidative effect and suppressive effect on LDL oxidation.

• Bulletin of the Korean Chemical Society
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• v.34 no.9
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• pp.2760-2764
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• 2013

Geniposide is a biologically active ingredient of gardenia fruit. A liquid chromatography-tandem mass spectrometric method was developed and validated for the determination of geniposide in rat plasma. The plasma samples were pretreated by solid-phase extraction and introduced into a BDS Hypersil $C_{18}$ column ($50{\times}2.1mm$, $5{\mu}m$) for chromatographic separation. The mobile phase consisted of 0.1% formic acid and 0.1% formic acid in acetonitrile, and gradient elution was performed at a flow rate of 0.25 mL/min. For mass spectrometric detection, multiple reaction monitoring was performed via an electrospray ionization source in positive mode. The calibration curve for geniposide was linear ($r^2=0.997$) in the concentration range of $0.005-1{\mu}g/mL$. The intra- and inter-day accuracies and precisions fulfilled the required criteria (${\pm}15%$). The developed method was subsequently used for pharmacokinetic analysis of geniposide after oral administration to rats at a dose of 50 mg/kg. The mean maximum plasma concentration of geniposide was $0.68{\pm}0.29{\mu}g/mL$ at $0.44{\pm}0.13h$, and the mean area under the plasma concentration versus time curve was $1.46{\mu}g{\cdot}h/mL$.

• Journal of Digital Convergence
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• v.10 no.6
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• pp.331-339
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• 2012

The easy and simple simultaneous analytical method of preservatives (BA, SA, DHA, MP, EP, IPP, PP, IBP and BP) was studied by more easily changing from method used in food and drug using HPLC with scherzo SM-C18 column. All presevatives were seperated successfully in mobile phase of 50 mM ammonium formate : 0.1% phosphoric acid (50:50 v/v%) and 50 mM ammonium formate : acetonitrile (30 : 70). Retention time of BA, SA, DHA, MP, EP, IPP, PP, IBP and BP was 7.74, 9.08, 12.57, 13.83, 21.62, 27.29, 28.20, 33.20 and 33.68 min, respectively. The calibration curves of BA, SA, DHA, MP, EP, IPP, PP, IBP and BP were linear over the concentration range of 5~80 ${\mu}g/mL$ with correlation coefficient of above 0.999. The limit of detection (LOD) and limit of quantitation (LOQ) of BA, SA, DHA, MP, EP, IPP, PP, IBP and BP were 0.52 and 1.58, 1.09 and 3.29, 1.00 and 3.03, 1.36 and 4.13, 1.26 and 3.83, 1.02 and 3.08, 1.11 and 3.37, 0.82 and 2.48, 0.85 and 2.59 ${\mu}g/mL$, respectively. The coefficients of variation for intra- and inter-day assay were 0.12~2.68 and 0.18~2.66%, respectively. The developed method showed good intra- and inter-day precision and accuracy. The preservatives used in mouthwashes were BA, MP and PP and were detected in 24 samples(86%) except for 4 samples and not showed significant difference in using dose of adult and children. In conclusion, the developed method can be useful for simultaneous analysis of preservatives in mouthwashes and these results suggest that could be applied to fundamental study and guideline on content of preservatives in mouthwashes.

• Korean Journal of Pharmacognosy
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• v.45 no.4
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• pp.300-314
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• 2014

An ultra-performance liquid chromatography-electrospray ionization-mass spectrometer (UPLC-ESI-MS) method was established for the simultaneous quantification of eighteen marker compounds in traditional Korean formula, Cheonwangbosimdan (CWBSD). In addition, we evaluated the antioxidant effects of CWBSD. Eighteen marker components were separated on a UPLC BEH $C_{18}$ analytical column ($2.1{\times}100mm$, $1.7{\mu}m$) and kept at $45^{\circ}C$ by gradient elution with 0.1% (v/v) formic acid in water and acetonitrile as mobile phase. The flow rate was 0.3 mL/min and the injection volume was $2.0{\mu}L$. The antioxidant activities of CWBSD were assessed by measuring free radical scavenging activities on 2,2'-azinobis-3-ethylbenzothiazoline-6-sulfonic acid (ABTS) and 1-1-diphenyl-2-picrylhydrazyl (DPPH). The calibration curves of all analytes showed good linearity (correlation coefficient ${\geq}0.9937$) within the test ranges. The limits of detection and quantification for the 18 marker compounds were 0.01-4.71 ng/mL and 0.03-14.13 ng/mL, respectively. The contents of the 18 compounds in CWBSD extract ranged from none to $1701.00{\mu}g/g$. The CWBSD showed the radical scavenging activity in a dose-dependent manner. The concentration required for 50% reduction ($RC_{50}$) against ABTS and DPPH radicals were $149.42{\mu}g/mL$ and $339.24{\mu}g/mL$.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.14 no.3
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• pp.595-605
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• 1994

The field observations. data analyses and numerical experiments are performed to investigate the short and long term beach deformation mechanisms in Haeundae beach. The schematic diagrams of deposition and erosion mechanism due to the attack of typhoons are described from the analysis on the beach widths and profiles. The short term beach deformation depends strongly on the characteristics of incident waves and wave-induced currents. The main incident wave and the calibration parameters of the shoreline change model are determined using the beach width data. Beacause the main incident wave approaches obliquly from the SE direction, the net westward longshore sediment transport occurs. Therefore the unbalance of longshore sediment budget in the east of the beach where the sediment source dose not exist causes a beach erosion. On the other hand, the deposited sand in the west is lost offshore by the storm wave action.