• The Korean Journal of Nuclear Medicine Technology
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• v.20 no.1
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• pp.59-65
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• 2016

Purpose Dynamic kidney scan is a typical imaging technique that visualizes kidney function. Reproducibility of dynamic kidney scans has been evaluated by comparing low-dose kidney scans with low-dose radiopharmaceutical and standard dynamic kidney scan. With this comparative study, if reproducibility is superb, the dynamic kidney scan method with reduced radioactivity to patients is to be utilized and radiation exposure to patient is to be reduced. Materials and Methods For gamma camera, Orbiter, SymbiaE (Siemens, Germany) was used. Among patients who had used 370 Mbq (10 mCi) from January of 2013 to February 2014 and other patients who had used 185 Mbq (5 mCi) from March of 2014 to July of 2015 with identical condition, 21 subjects using DTPA and 20 subjects using $MAG_3$, 41 subjects in total, had been selected as subjects for data. From renogram of the result image, frame of the peak point was selected. Then, region of interest of kidney and background had been selected and Kidney to Background Ratio has been calculated for comparison. Results In tests using DTPA, kidney to background ratio when using 370 Mbq was $5.67{\pm}0.8$ at average while it was $5.62{\pm}0.87$ when using 185 Mbq, which didn't show much difference. Also in the tests using $MAG_3$, kidney to background ratio when using 370 Mbq was $14.95{\pm}2.58$ at average and $14.56{\pm}2.02$ in 185 Mbq, which neither showed much difference. In paired sample t-test, p-value was 0.566 in DTPA and 0.363 in $MAG_3$, which confirmed that there was no difference between the groups. Conclusion In identical patients, when dose was decreased from 370 Mbq to 185 Mbq, reproducibility of dynamic kidney scan was proven to be excellent. Low-dose Dynamic kidney scan can achieve results with fine reproducibility without improvement in performance of gamma camera and is expected to reduce radiation exposure to patient.

• Journal of Radiation Protection and Research
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• v.40 no.1
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• pp.1-9
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• 2015

Compton cameras overcome several limitations of conventional mechanical collimation based gamma imaging devices, such as pin-hole imaging devices, due to its electronic collimation based on coincidence logic. Especially large-scale Compton camera has wide field of view and high imaging sensitivity. Those merits suggest that a large-scale Compton camera might be applicable to monitoring nuclear materials in large facilities without necessity of portability. To that end, our research group have made an effort to design a large-scale Compton camera for safeguard application. Energy resolution or position resolution of large-area detectors vary with configuration style of the detectors. Those performances directly affect the image quality of the large-scale Compton camera. In the present study, a series of Geant4 Monte Carlo simulations were performed in order to examine the effect of those detector parameters. Performance of the designed large-scale Compton camera was also estimated for various monitoring condition with realistic modeling. The conclusion of the present study indicates that the energy resolution of the component detector is the limiting factor of imaging resolution rather than the position resolution. Also, the designed large-scale Compton camera provides the 16.3 cm image resolution in full width at half maximum (angular resolution: $9.26^{\circ}$) for the depleted uranium source considered in this study located at the 1 m from the system when the component detectors have 10% energy resolution and 7 mm position resolution.

• Journal of the Korean Society of Radiology
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• v.13 no.4
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• pp.503-508
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• 2019

In short a binary value according to a change in the tube voltage by using one of VOLUME AXIAL MODE of scanning techniques of chest CT image quality evaluation in order to obtain high image and to present the appropriate tube voltage. CT instruments were GE Revolution (GE Healthcare, Wisconsin USA) model and Phantom used Pediatric Whole Body Phantom PBU-70. The test method was examined in Volume Axial mode using the pediatric protocol used in the Y university hospital of mass-produced material. The tube voltage was set to 70kvp, 80kvp, 100kvp, and mAs was set to smart mA-ODM. The mean SNR difference of the heart was $-4.53{\pm}0.26$ at 70 kvp, $-3.34{\pm}0.18$ at 80 kvp, $-1.87{\pm}0.15$ at 100 kvp, and SNR at 70 kvp was about -2.66 higher than 100 kvp and statistically significant (p<0.05) In the Lung SNR mean difference analysis, $-78.20{\pm}4.16$ at 70 kvp, $-79.10{\pm}4.39$ at 80 kvp, $-77.43{\pm}4.72$ at 100 kvp, and SNR at 70 kvp at about -0.77 higher than 100 kvp were statistically significant. (p<0.05). Lung CNR mean difference was $73.67{\pm}3.95$ at 70 kvp, $75.76{\pm}4.25$ at 80 kvp, $75.57{\pm}4.62$ at 100 kvp and 20.9 CNR at 80 kvp higher than 70 kvp and statistically significant (p<0.05) At 100 kvp of tube voltage, the SNR was close to 1 while maintaining the quality of the heart image when 70 kvp and 80 kvp were compared. However, there is no difference in SNR between 70 kvp and 80 kvp, and 70 kvp can be used to reduce the radiation dose. On the other and, CNR showed an approximate value of 1 at 70 kvp. There is no difference between 80 kvp and 100 kvp. Therefore, 80 kvp can reduce the radiation dose by pediatric chest CT. In addition, it is possible to perform a scan with a short scan time of 0.3 seconds in the volume axial mode test, which is useful for pediatric patients who need to move or relax.

• Journal of Food Hygiene and Safety
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• v.28 no.3
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• pp.258-266
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• 2013

This study was conducted to determine the PSL and TL properties of foods irradiated with electron beam and gamma-ray. 5 kinds of food including cereal, pulse, fish powder, dried vegetable and tea were irradiated at 0 to 10 kGy by electron beam accelerator or $^{60}Co$ gamma-ray irradiator. The PSL analysis showed negative results for most of the non-irradiated samples. Non-irradiated shrimp powder showed intermediate result. Irradiated samples gave negative or intermediate or positive value which presented the limitation of PSL technique. In TL analysis, there were TL glow curves at around $300^{\circ}C$ with low intensity on non-irradiated samples. Maximum peak in the range of $150-250^{\circ}C$ was appeared on irradiated samples. TL ratio obtained by re-irradiation with 1 kGy was less than 0.1 on non-irradiated samples and higher than 0.1 on irradiated samples. Therefore, in PSL measurement, electron-beam irradiated samples could obtain more clear results. TL analysis showed obvious difference between non-irradiated and irradiated samples. But the identification was impossible for the sample of rice and lemon tea. Because of it's low contents of mineral.

• Journal of the Korean Society of Radiology
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• v.7 no.3
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• pp.213-219
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• 2013

Currently, about 35 cyclotrons have been operating in South Korea. Most of them are mainly used for the synthesis of radiopharmaceuticals such as $^{18}FDG$, which is a cancer tracer for nuclear medicine. Highly enriched $H_2{^{18}}O$ containing up to 98% of $^{18}O/O$ isotope ratio is used as the target for $^{18}F$ production. The price of the highly enriched $H_2{^{18}}O$ ranges 60~70 USD/g, and all of them have been imported from foreign country in spite of the very expensive price. The target (enriched $H_2{^{18}}O$) is non-radioactive before the proton beam irradiation. But, the post-irradiation target (used $H_2{^{18}}O$) must be managed following the National Radiation Safety Regulations, because it turns into radioactive by the radioactivation of the impurities within the target. Recently, nevertheless of the fast increasing amount of used $H_2{^{18}}O$ in accordance with the increasing number of nuclear medicine cases, any activation analysis on the used $H_2{^{18}}O$ have been conducted yet in Korea. In this research, activation analysis have been conducted to confirm the specific radioactivity(Bq/g) of each radioisotopes within the used $H_2{^{18}}O$. The analysis have been done on the 3 of 20g samples collected from the used $H_2{^{18}}O$ storages at different cyclotron centers. Based on the results, it was confirmed that the "used $H_2{^{18}}O$" contains gamma emitters such as $^{56}Co$, $^{57}Co$, $^{58}Co$, and $^{54}Mn$ as well as the considerable amount of beta emitter $^3H$. It was also confirmed that the only one sample contained over exemption level of gamma emitters while the specific activity of tritium was lower than the exemption level in all samples. The specific activity of radioisotopes were measured different levels in the samples depending on the elapsed time after irradiation. Further study on the activation of the "used $H_2{^{18}}O$" is definitely necessary, nevertheless the as-is results of this research must be useful in establishing a rational "used $H_2{^{18}}O$" management protocol.

• Journal of Korean Society of Environmental Engineers
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• v.38 no.1
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• pp.42-46
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• 2016

The radioactive iodine ($^{131}I$) presents in the environment through the excrete process of nuclear medicine patients. In the detecting of low level of $^{131}I$ in the public water, the counting uncertainty has an effect on the accuracy and reliability of detecting $^{131}I$ radioactivity concentration. In this study, the contribution of sample amount, radioactivity concentration and counting time to the uncertainty was investigated in the case of public water sample. Sampling points are public water and the effluents of a sewage treatment plant at Sapkyocheon stream, Geumgang river. In each point, 1, 10 and 20 L of liquid samples were collected and prepared by evaporation method. The HPGe (High Purity Germanium) detector was used to detect and analyze emitted gamma-ray from samples. The radioactivity concentration of $^{131}I$ were in the range of 0.03 to 1.8 Bq/L. The comparison of the counting uncertainty of the sample amount, 1 L sample is unable to verify the existence of the $^{131}I$ under 0.5 Bq/L radioactivity concentration. Considering the short half-life of $^{131}I$ (8.03 days), a method for measuring 1 L sample was used. However comparing the detecting and preparing time of 1, 10 L respectively, detecting 10 L sample would be an appropriate method to distinguish $^{131}I$ concentration in the public water.

• Progress in Medical Physics
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• v.25 no.1
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• pp.31-36
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• 2014

We aimed to evaluate the dosimetric characteristics of reproducibility, linearity and dose dependence of optical stimulated luminance dosimeter (OSLD) in the Co-60 Gamma-rays and to analyze with a precedent study in field of the diagnostic radiography and radiotherapy. The reproducibility was 0.76% of the coefficient of variation, the homogeneity was within 1.5% of the coefficient of variation and OSLD had supra-linear response more than 3 Gy. So the correlation between dose and count was fitted by quadratic function. The count depletion by repeated reading was 0.04% per reading regardless of the irradiated dose. And the half time of decay curve according to the irradiated dose was 0.68 min. with 1 Gy, 1.04 min. with 5 Gy, and 1.10 min. with 10 Gy, respectively. In case of annealing for 30 min, the removal rate was 88% with 1 Gy, 90% with 5 Gy, and 92% with 10 Gy, respectively and 99% in case of annealing time for 4 hour. It is feasible to use OSLDs for dose evaluation in Co-60 Gamma-rays when considering the uncertainty on the procedure according to the irradiated dose.

• Journal of Life Science
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• v.20 no.7
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• pp.1054-1065
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• 2010

SH21B is a natural composition composed of seven herbs: Scutellaria baicalensis Georgi, Prunus armeniaca Maxim, Ephedra sinica Stapf, Acorus gramineus Soland, Typha orientalis Presl, Polygala tenuifolia Willd and Nelumbo nucifera Gaertner (Ratio 3:3:3:3:3:2:2). In our previous study, we reported that SH21B inhibited adipogenesis and fat accumulation in 3T3-L1 cells through modulation of various regulators in the adipogenesis pathway. The aim of this study was to analyze the transcriptome profiles for the anti-adipogenic effects of SH21B in 3T3-L1 cells. Total RNAs from SH21B-treated 3T3-L1 cells were reverse-transcribed into cDNAs and hybridized to Affymetrix Mouse Gene 1.0 ST array. From microarray analyses, we identified 2,568 genes of which expressions were changed more than two-fold by SH21B, and the clustering analyses of these genes resulted in 9 clusters. Three clusters among the 9 showed down-regulation by SH21B (cluster 4, cluster 6 and cluster 9), and two clusters showed up-regulation by SH21B (cluster 7 and cluster 8) during the adipogenesis of 3T3-L1 cells. It was found that many genes related to cell proliferation and adipogenesis were included in these clusters. Clusters 4, 6 and 9 included genes which were related with adipogenesis induction and cell cycle arrest. Clusters 7 and 8 included genes related to cell proliferation as well as adipogenesis inhibition. These results suggest that the mechanisms of the anti-adipogenic effects of SH21B may be the modulation of genes involved in cell proliferation and adipogenesis.

• Korean Journal of Food Science and Technology
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• v.34 no.6
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• pp.962-968
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• 2002

Effects of gamma-irradiation of 1 to 10 kGy on the microbial growth, contents of amino acids, fatty acids, and free sugars, and changes in acid values in soybean powder were studied. Irradiation doses at $3{\sim}5\;kGy$ inhibited the mold growth completely in two kinds of imported soybean powders. Contents of sulfur-containing amino acids, such as cysteine, in both soybean powders decreased with irradiation, whereas no significant changes in free amino acid and fatty acid contents of both soybean powders were observed. Free sugar contents of stachyose and sucrose in Chinese soybean powder decreased with increasing irradiation dose level, whereas, those of other sugars remained unchanged. Results of this study confirm that $3{\sim}5\;kGy$ irradiation can be safely applied to apply to soybean powder without causing significant quality deteriorations microbiologically and chemically.

• Journal of radiological science and technology
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• v.38 no.1
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• pp.23-30
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• 2015

Positron emission tomography scan has been growing diagnostic equipment in the development of medical imaging system. Compare to 99mTc emitting 140 keV, Positron emission radionuclide emits 511 keV gamma rays. Because of this high energy, it needs to reduce radioactive emitting from patients for radio technologist. We searched the external dose rates by changing distance from patients and measure the external dose rates when we used shielder investigate change external dose rates. In this study, the external dose distribution were analyzed in order to help managing radiation protection of radio technologists. Ten patients were searched (mean age: $47.7{\pm}6.6$, mean height: $165.5{\pm}3.8cm$, mean weight: $65.9{\pm}1.4kg$). Radiation was measured on the location of head, chest, abdomen, knees and toes at the distance of 10, 50, 100, 150, and 200 cm, respectively. Then, all the procedure was given with a portable radiation shielding on the location of head, chest, and abdomen at the distance of 100, 150, and 200 cm and transmittance was calculated. In 10 cm, head ($105.40{\mu}Sv/h$) was the highest and foot($15.85{\mu}Sv/h$) was the lowest. In 200 cm, head, chest, and abdomen showed similar. On head, the measured dose rates were $9.56{\mu}Sv/h$, $5.23{\mu}Sv/h$, and $3.40{\mu}Sv/h$ in 100, 150, and 200 cm, respectively. When using shielder, it shows $2.24{\mu}Sv/h$, $1.67{\mu}Sv/h$, and $1.27{\mu}Sv/h$ in 100, 150, and 200 cm on head. On chest, the measured dose rates were $8.54{\mu}Sv/h$, $4.90{\mu}Sv/h$, $3.44{\mu}Sv/h$ in 100, 150, and 200 cm, respectively. When using shielder, it shows $2.27{\mu}Sv/h$, $1.34{\mu}Sv/h$, and $1.13{\mu}Sv/h$ in 100, 150, and 200 cm on chest. On abdomen, the measured dose rates were $9.83{\mu}Sv/h$, $5.15{\mu}Sv/h$, and $3.18{\mu}Sv/h$ in 100, 150, and 200 cm, respectively. When using shielder, it shows $2.60{\mu}Sv/h$, $1.75{\mu}Sv/h$, and $1.23{\mu}Sv/h$ in 100, 150, and 200 cm on abdomen. Transmittance was increased as the distance was expanded. As the distance was further, the radiation dose were reduced. When using shielder, the dose were reduced as one-forth of without shielder. The Radio technologists are exposed of radioactivity and there were limitations on reducing the distance with Therefore, the proper shielding will be able to decrease radiation dose to the technologists.