• Journal of Radiation Protection and Research
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• v.37 no.4
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• pp.167-172
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• 2012

Jeju Island is a significant area as a reference site of in situ gamma spectrometry because there are a number of open spaces which includes $^{137}Cs$ above a certain level. In this paper, the pasture within the Hallasan National Park was selected as one of the open spaces of Jeju Island. The homogeneity of $^{137}Cs$ at the site was assessed by analysis of variance on count and by radioactivity concentration obtained through in situ gamma spectrometry. For this purpose, the count of a total of 79 points at 3 sites were measured with less than count uncertainty of 5% for 2000 seconds. In the results of the analysis of variance, the 2 sites were homogeneous, and the remaining 1 site can be specified to be homogeneous through the adjustment of measuring range. The distribution of radioactivity concentration calculated by in situ gamma spectrometry were $53.7{\sim}93.2Bq\;kg^{-1}$, $30.5{\sim}61.0Bq\;kg^{-1}$ and $48.8{\sim}102Bq\;kg^{-1}$ at each site.

• Journal of Environmental Impact Assessment
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• v.27 no.5
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• pp.405-416
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• 2018

In this research, the distribution of Platinum Group Elements (PGEs) at roadside dust in Daejeon, Korea was examined using an ICP-MS (Inductively Coupled Plasma-Mass Spectrometry) technique. For the quality assurance of the determination, method validation based on its accuracy and precision was conducted using SRM (Standard Reference Material). It was found that the relative errors of Pt, Pd, and Rh against each SRM value were -0.7%, -10.0%, and -20.4%, respectively, while relative standard deviations for three elements were less than 10%. The concentrations of Pt, Pd and Rh in roadside dust averaged as $17.4{\pm}9.2{\mu}g/kg$, $283.6{\pm}20.5{\mu}g/kg$, and $7.3{\pm}2.8{\mu}g/kg$, respectively. The concentrations of Pt and Rh have significantly higher distribution patterns in the dust at roadside and underground parking lot than those in soil of the background or other urban area. The correlation analysis between concentrations of PGEs in roadside dust indicates that the distribution of Pt and Rh concentration were strongly affected by automobile sources.

• The Korean Journal of Nuclear Medicine
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• v.5 no.2
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• pp.57-64
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• 1971

The organ distribution study and the whole body scan were done in the albino rats at intervals of 5, 30, 60, 90 and 120 minutes after the intravenous injection of $^{99m}TC$-pertechnetate absorbed in Sephadex beads of $20{\sim}80$ micra in diameter. Effect of additional injection of physiological saline and saline absorbed in Sephadex beads of $20{\sim}80$ micra in diameter on the scan and organ distribution were also studied. The results were as follows. 1. Five minutes after the injection of $^{99m}TC$-pertechnetate absorbed in Sephadex beads of $20{\sim}80$ micra in diameter, Sephadex was well trapped in the lungs, with which the excellent lung scan was obtained. Two hours after the injection, kidneys were well visualized instead of lungs, which suggested that kidney acts as the excretory organ. Five minutes prior to scan, additional injection of physiological saline absorbed in Sephadex above mentioned was done. The bladder was also well visualized together with the kidneys. 2. In the distribution studies, most of radioactivity was detected in the lungs at 5 minutes and was gradually transferred chiefly to the kidneys and bladder and partly to the liver. 3. Additional injection of physiological saline resulted in a rapid transfer of $^{99m}TC$ trapped in the lung to both the kidneys and liver. 4. Additional injection of physiological saline absorbed in Sephadex beads of $20{\sim}80$ micra in diameter resulted in a rapid transfer of $^{99m}TC$ trapped in the lung to only the urinary system. 5. Results of these studies suggested that; a) Other nutrients and therapeutic compounds may be carried into the lungs along with Sephadex beads and then released in high concentration, which would exert greater therapeutic effect locally than that of the usual administration. b) Some radionuclides absorbed in Sephadex could be used as the lung scan agents, the flushing out of which by Sephadex-saline also give satisfactory renal and bladder scans. c) Other potent therapeutic radionuclides could be retained for some time by this method, which can be in the lungs easily flushed out within 2 hours.

• Nuclear Engineering and Technology
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• v.55 no.11
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• pp.3940-3955
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• 2023

A new method of numerical simulating prediction and decontamination effect evaluation for abrasive jet decontamination to radioactively contaminated metal is proposed. Based on the Computational Fluid Dynamics and Discrete Element Model (CFD-DEM) coupled simulation model, the motion patterns and distribution of abrasives can be predicted, and the decontamination effect can be evaluated by image processing and recognition technology. The impact of three key parameters (impact distance, inlet pressure, abrasive mass flow rate) on the decontamination effect is revealed. Moreover, here are experiments of reliability verification to decontamination effect and numerical simulation methods that has been conducted. The results show that: ⁶⁰Co and other homogeneous solid solution radioactive pollutants can be removed by abrasive jet, and the average removal rate of Co exceeds 80%. It is reliable for the proposed numerical simulation and evaluation method because of the well goodness of fit between predicted value and actual values: The predicted values and actual values of the abrasive distribution diameter are Ф57 and Ф55; the total coverage rate is 26.42% and 23.50%; the average impact velocity is 81.73 m/s and 78.00 m/s. Further analysis shows that the impact distance has a significant impact on the distribution of abrasive particles on the target surface, the coverage rate of the core area increases at first, and then decreases with the increase of the impact distance of the nozzle, which reach a maximum of 14.44% at 300 mm. It is recommended to set the impact distance around 300 mm, because at this time the core area coverage of the abrasive is the largest and the impact velocity is stable at the highest speed of 81.94 m/s. The impact of the nozzle inlet pressure on the decontamination effect mainly affects the impact kinetic energy of the abrasive and has little impact on the distribution. The greater the inlet pressure, the greater the impact kinetic energy, and the stronger the decontamination ability of the abrasive. But in return, the energy consumption is higher, too. For the decontamination of radioactively contaminated metals, it is recommended to set the inlet pressure of the nozzle at around 0.6 MPa. Because most of the Co elements can be removed under this pressure. Increasing the mass and flow of abrasives appropriately can enhance the decontamination effectiveness. The total mass of abrasives per unit decontamination area is suggested to be 50 g because the core area coverage rate of the abrasive is relatively large under this condition; and the nozzle wear extent is acceptable.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.14 no.4
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• pp.343-356
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• 2016

The Korea Radioactive Waste Agency (KORAD) has developed a dual-purpose metal cask for the dry storage of spent nuclear fuel that has been generated by domestic light-water reactors. The metal cask was designed in compliance with international and domestic technology standards, and safety was the most important consideration in developing the design. It was designed to maintain its integrity for 50 years in terms of major safety factors. The metal cask ensures the minimization of waste generated by maintenance activities during the storage period as well as the safe management of the waste. An activation evaluation of the main body, which includes internal and external components of metal casks whose design lifetime has expired, provides quantitative data on their radioactive inventory. The radioactive inventory of the main body and the components of the metal cask were calculated by applying the MCNP5 ORIGEN-2 evaluation system and by considering each component's chemical composition, neutron flux distribution, and reaction rate, as well as the duration of neutron irradiation during the storage period. The evaluation results revealed that 10 years after the end of the cask's design life, $^{60}Co$ had greater radioactivity than other nuclides among the metal materials. In the case of the neutron shield, nuclides that emit high-energy gamma rays such as $^{28}Al$ and $^{24}Na$ had greater radioactivity immediately after the design lifetime. However, their radioactivity level became negligible after six months due to their short half-life. The surface exposure dose rates of the canister and the main body of the metal cask from which the spent nuclear fuel had been removed with expiration of the design lifetime were determined to be at very low levels, and the radiation exposure doses to which radiation workers were subjected during the decommissioning process appeared to be at insignificant levels. The evaluations of this study strongly suggest that the nuclide inventory of a spent nuclear fuel metal cask can be utilized as basic data when decommissioning of a metal cask is planned, for example, for the development of a decommissioning plan, the determination of a decommissioning method, the estimation of radiation exposure to workers engaged in decommissioning operations, the management/reuse of radioactive wastes, etc.

• The Korean Journal of Nuclear Medicine
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• v.32 no.4
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• pp.382-390
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• 1998

Purpose: The purpose of this study was to evaluate the accuracy of radioactivity quantitation in Tc-99m SPECT by using combined scatter and attenuation correction. Materials and Methods: A cylindrical phantom which simulates tumors (T) and normal tissue (B) was filled with varying activity ratios of Tc-99m. We acquired emission scans of the phantom using a three-headed SPECT system (Trionix, Inc.) with two energy windows (photopeak window: $126{\sim}154keV$ and scatter window: $101{\sim}123keV$). We performed the scatter correction with dual-energy window subtraction method (k=0.4) and Chang attenuation correction. Three sets of SPECT images were reconstructed using combined scatter and attenuation correction (SC+AC), attenuation correction (AC) and without any correction (NONE). We compared T/B ratio, image contrast [(T-B)/(T+B)] and absolute radioactivity with true values. Results: SC+AC images had the highest mean values of T/B ratios. Image contrast was 0.92 in SC+AC, which was close to the true value of 1, and higher than AC (0.77) or NONE (0.80). Errors of true activity by SPECT images ranged from 1 to 11% for SC+AC, $22{\sim}47%$ for AC, and $2{\sim}16%$ for NONE in a phantom which was located 2.4cm from the phantom surface. In a phantom located 10.0cm from the surface, SC+AC underestimated by 24%, NONE 40%. However, AC overestimated by 10%. Conclusion: We conclude that accurate SPECT activity quantitation of Tc-99m distribution can be achieved by dual window scatter correction combind with attenuation correction.

• Radiation Oncology Journal
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• v.22 no.4
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• pp.288-297
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• 2004

Puporse: The aims of this study were to evaluate the change of $[^18F]fluoromisonidazole$($[^18F]FMISO$) uptake in C3H mouse squamous cell carcinoma-VII (SCC-VII) treated with mild hyperthermia ($42^{circ}C$) and nicotinamide and to assess the biodistribution of the markers in normal tissues under similar conditions. Methods and Materials: $[^18F]FMISO$ was producedby our hospital. Female C3H mice with a C3H SCC-VII tumor grown on their extremities were used. Tumors were size matched. Non-anaesthetized, tumor-bearing mice underwent control or mild hyperthermia at $42^{circ}C$ for 60 min with nicotinamide (50 mg/kg i.p. injected) and were examined by gamma counter, autoradiography and animal PET scan 3 hours after tracer i.v. injected with breathing room air, The biodistribution of these agents were obtained at 3 h after $[^18F]FMISO$ injection. Blood, tumor, muscle, heart, lung, liver, kidney, brain, bone, spleen, and intestine were removed, counted for radioactivity and weighed. The tumor and liver were frozen and cut with a cryomicrotome into 10- um sections. The spatial distribution of radioactivity from the tissue sections was determined with digital autoradiography. Results: The mild hyperthermia with nicotinamide treatment had only slight effects on the biodistribution of either marker in normal tissues. We observed that the whole tumor radioactivity uptake ratios were higher in the control mice than in the mild hyperthermia with nicotinamide treated mice for $[^18F]FMISO$ ($1.56{\pm}1.03$ vs. $0.67{\pm}0.30$; p=0.063). In addition, autoradiography and animal PET scan demonstrated that the area and intensity of $[^18F]FMISO$ uptake was significantly decreased. Conclusion: Mild hyperthermla and nicotinamide significantly improved tumor hypoxia using $[^18F]FMISO$ and this uptake reflected tumor hypoxic status.

• Journal of Biomedical Engineering Research
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• v.16 no.2
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• pp.231-238
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• 1995

Tc-99m-MIBI (Sestamibi) myocardial SPECT along with TI-201 tomographic Imaging has demonstrated wide application and high image quality sufficient for the diagnosis of myocardial perfusion defect, which consequently reflects regional myocardial blood flow. The qualitative values of myocardial SPECT with Tc-99m-MIBI as well ds the quantitative cases depend in some degree on the reconstruction techniques of multiple projections. Filtered backprojection (FBP) Is the common standard method for reconstruction rather than the complicated and time-consuming arithmetic methods. In FBP it is known that the distribution of radioactivity in reconstructed transverse slices varies with the selected litter parameters such as cutoff frequencies and order (Butterworth case) The cutoff frequencies used in clinicAl practice partially remove and decrease the true radioactive distribution and alter the pixel counts, which lead to underestimation of true counts in specific myocardial regions. In this study, we have investigated the effect of cutoff frequencies of reconstruction filter on the artifactually induced perfusion defects, which are often demonstrated near inferior and/or inferoseptal cardiac walls due to the intense hepatic uptake of Tc-99m-MIBI. A computerized method for Identifying the relative degree of artifactual perfusion defect and for comparing those degrees along with the relative amount of hepatic uptake to myocardium was developed and patient images were studied to observe the quantitative degree of underestimation of myocardial perfusion, and to propose some reasonable threshold of cutoff frequency in the diagnosis of perfusion defect quantitatively. We concluded that from the quantitative viewpoint cutoff frequencies may be used as high as possible with the sacrifice of homogeneity of image quality, and those frequencies lower than the common 0.3 Wyquist frequency would reveal severe degradation of radioactive distribution near inferior and/or inferoseptal myocardium when applying Butterworth or low pass filter.

• Journal of Radiopharmaceuticals and Molecular Probes
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• v.3 no.1
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• pp.18-24
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• 2017

Patient-specific image-based internal dosimetry involves using the patient's individual anatomy and spatial distribution of radioactivity over time to obtain an absorbed dose calculation. Individual absorbed dose was calculated by accumulated activity multiply S-value of each organs. The aim of this study was to calculate the S-values using Monte Carlo simulation in monkey and mouse and evaluation of absorbed dose in each organ. Self-irradiation S-value of monkey heart self-irradiation was 3.15E-03 mGy-g/MBq-s, lung self-irradiation was 8.94E-04 mGy-g/MBq-s and liver self-irradiation S-value was 2.23E-03 mGy-g/MBq-s. Mouse heart self-irradiation S-value was 1.95E-01 mGy-g/MBq-s, lung was 9.59E-02 mGy-g/MBq-s, and liver was 1.40E-03 mGy-g/MBq-s. The results of this study show that the calculation protocol of image based individual absorbed dose of each organ using Monte Carlo simulation. Therefore, this study may be applied to calculate human specific absorbed dose.

• Korean Journal of Environmental Agriculture
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• v.16 no.1
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• pp.25-30
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• 1997

Absorption, distribution, metabolism and excretion of $^{14}C-carbofuran$(2,3-dihydro-2,2-dimethyl-7-benzofuranyl methylcarbamte) were studied in carp(Cyprinus carpio L.) after the treatment of carbofuran at the dose level of 43 parts per billion. Maximum radioactivities in tissues(liver, kidney, gut, gall bladder) and blood of carp were shown 12hrs after the treatment of $^{14}C-carbofuran$. Carbofuran was metabolized to 3-hydroxycarbofuran and 3-ketocarbofuran in liver and kindney of carp, and the major metabolite was 3-hydroxycarbofuran. Most radioactivity absorbed into the carp tissues was eliminated 3hrs after transfer of the carp to fresh water. The excretory metabolites were 3-ketocarbofuran(32.3%), 3-hydroxycarbofuran(52.8%) and an unknown metabolite(2.6%) during the period of 3hrs of the excretory experiment.