• Journal of radiological science and technology
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• v.42 no.2
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• pp.99-104
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• 2019

Mammography, conducted every two years, causes cancer due to regular exposure to radiation while reducing rate of death caused by breast cancer. The study evaluates the effect of breast shielding apron made to shield off scattered radiation that occurs to the breast when the opposite side breast is mammogramed. AGD was measured using ACR phantom, composed of 50% mammary glands and 50% fat, and radiation was measured before and after wearing the apron on the breast when the opposite side of the breast is mammogramed. When CC direction mammography was conducted to a breast, the AGD was 1.84 mGy. When CC direction and MLO direction mammography were done to a breast, the average dose detected from the opposite side breast from four directions(top to bottom and medial to lateral) was $140{\mu}Gy$ with maximum dose of $256{\mu}Gy$ at medial side. After putting on the apron, the dose, caused by scattered radiation, was not detected from any of the four directions. Using of breast shielding apron is expected to minimize the radiation exposure by blocking scattered radiation to the breast shielded, when mammography is done to the opposite side breast.

• Nuclear Engineering and Technology
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• v.56 no.1
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• pp.335-339
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• 2024

Employees of nuclear medicine facilities performing medical procedures with the use of open radioactive sources require continuous detailed control of exposure to ionizing radiation. Thermoluminescent (TL) detectors placed in dosimeters: for the whole body, for lenses, ring and wrist dosimeters were used to assess exposure. The highest whole-body exposure of (1.70 ± 1.09) µSv/GBq was recorded in nurses administering radiopharmaceutical to patients. The highest exposure to lenses and fingers was recorded for employees of the quality control zone and it was (8.08 ± 2.84) µSv/GBq and a maximum of (1261.46 ± 338.93) µSv/GBq, respectively. Workers in the production zone received the highest doses on their hands, i.e. (175.67 ± 13.25) µSv/GBq. The measurements performed showed that the analyzed workers may be classified as exposure category A. Wrist dosimeters are not recommended for use in isotope laboratories due to underestimation of ionizing radiation doses. Appropriately selected shields, which significantly reduce the dose received by employees, must be used in isotope laboratories. Periodic measurements confirmed that the appropriate optimization of exposure reduces the radiation doses received by employees.

• Journal of Radiation Industry
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• v.17 no.2
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• pp.135-141
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• 2023

Tritium is used in various types of parts such as luminous bodies. These parts are maintained for inspection and replacement at a facility licensed to use radioactive isotopes. This study analyzed the concentration of tritium in working facilities to supplement and develop the safety management system for the maintenance environment of parts containing tritium. In addition, the internal exposure dose was evaluated to analyze the effects of leaked tritium when continuously exposed to workers. As a result of evaluating the internal exposure dose for workers for 30 days, the maximum was 9.70 μSv and the average was 1.45 μSv. Based on the results of this study, the internal radiation exposure safety of workers handling parts containing tritium was confirmed, and additional protective measures to prevent unnecessary exposure to tritium were suggested. This study is expected to contribute to supplementing and developing the radiation safety management system.

• Journal of applied mathematics & informatics
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• v.16 no.1_2
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• pp.355-369
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• 2004

The paper determines by control-theoretic means the optimal dose of fertilizer to be used to two plants for maintaining optimal revival of their growths, which are retarded mainly due to the toxicity contributed by the plants jointly.

• Journal of Radiation Protection and Research
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• v.33 no.4
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• pp.183-196
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• 2008

The internal dose by food consumption mostly accounts for radiological dose of public around nuclear power plants (NPPs). But, food consumption rates applied to off-site dose calculation in Korea which are the result of field investigation around Kori NPP by the KAERI (Korea Atomic Energy Research Institute) in 1988, are not able to reflect the latest dietary characteristics of Korean. The food consumption rates to be used for radiological dose assessment in Korea are based on the maximum individual of US NRC (Nuclear Regulatory Commssion) Regulatory Guide 1.109. However, the representative individual of the critical group is considered in the recent ICRP (International Commission on Radiological Protection) recommendation and European nations' practice. Therefore, the study on the re-establishment of the food consumption rates for individual around nuclear power plant sites in Korea was carried out to reflect on the recent change of the Korean dietary characteristics and to apply the representative individual of critical group to domestic regulations. The Ministry of Health and Welfare Affairs has investigated the food and nutrition of nations every 3 years based on the Law of National Health Improvement. The statistical data such as mean, standard deviation, various percentile values about food consumption rates to be used for the representative individual of the critical group were analyzed by using the raw data of the national food consumption survey in $2001{\sim}2002$. Also, the food consumption rates for maximum individual are re-estimated.

• Progress in Medical Physics
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• v.16 no.4
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• pp.176-182
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• 2005

Stereotactic radiosurgery (SRS) is a technique to deliver a high dose to a target region and a low dose to a critical organ through only one or a few irradiation. The SRS must be planned exactly. Currently the surgery plan is peformed by trial and error method. There are many questions about the reliability and reproducibility of the plan result. This study Improve each step of the Oh's method based on heuristic target shaping to obtain the better result. The target was reconstructed using cylinders with same height and the neighbored cylinders were combined according to the difference of each center and diameter. Then, spheres were packed within each cylinders by the packing rules. Two virtual targets were used to compare this method with Oh's method. As a result, the numbers of isocenter were successfully reduced - more than $35\%$ and $26\%$ - without serious differences of proscription isodose to tumour volume ratio (PITV) and maximum dose to proscription dose ratio (MDPD). This technique using cylinder piling and sphere packing will be a helpful tool to planner in stereotactic radiosurgery.

• Korean Journal of Microbiology
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• v.5 no.2
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• pp.69-78
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• 1967

Kim, Jong Hyup, (Div. of Biology, Atomic Energy Research Institute.) Studies on the Cellular Metabolism in Microorganisms as influenced by Gamma-irradiation(II). On respiration rate and dehydrogenase activity of yeast cells irradiated by gamma ray from cobalt-60. 1. Oxygen uptake rate of the gamma irraiated yeast cells had been measured with Warburg's manometer, and the $O_{2}$-uptake was compared with those of normal cells. The rate of endogetious respiration increases in its $O_2$-uptake at 150, 000 rentgen dose, and at higher rentoen doses it was decreased. Exogenous respiration begin to decrease in its O_2$-uptake at 5, 000r. doses of irradiation, further decrease with increasing of doses unproportionally. 2. It appears that plasma-membrane and nuclear membrane of yeast cells have changed and denatured by gamma-irradiation, as exogenous respiration of glucose had been decreased at a dose of 200, 000r's irradiation. 3. The activity of glucose, alcoholic, lactic, succinic and glutamic deliydrogenase (G.D.H., A.D.H., L.D.H., S.D.11., and GL.D.H.) in the gamma irradaited cells had been assayed by T.T.C.(Triphenyl tetrazolium chloride) method and spectrophotometry, the obtained results were compared with those of normal cells. 4. At a dose of and 10, 000 rentgens' irradiation of gamma ray, the activty of each debydrogenase (G.D.H., A.D.H., L.D.H., ) shows a sharp and highest peak in optical absorbalicy, but each abtivity of S.D.H and Gl.D.H shows its' maximum peak at a dose of 30, 000r. 5. The curve of each dehydrogenase activity was found to be rhythmical according to dose-rate of gamma irradiation. 6. Comparing with activity of debydrogenase each other, the maximum peak in optical absorbency can be arranged according to order as follows; glucose > alcoholoic > lactic > glutamic > succinic, this order is identical to the order of breakdown utility in respiration of normal yeast cells. 7. The activity of dehydrogenase experimented exhibit a resistance against gamma irradiation at lethal dose of cells, and the activity of dehydrogenase are found to be much resistant than those of respiratory system. We may assume that the membrane substrate of mitochondria or cytoplasm had been destructed by gamma-irradiation much more than that of dehydronase system.

• Journal of Veterinary Clinics
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• v.38 no.3
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• pp.135-142
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• 2021

The aim of this study was to evaluate the contrast effect if a saline flush following low-volume contrast medium bolus improves vascular and parenchymal enhancement using a saphenous vein in abdominal CT for small animals. Six clinically healthy beagle dogs underwent abdominal contrast-enhanced CT. They were divided into nine groups (each group, n = 6), according to the volume of contrast medium 1, 2, and 3 mL/kg, and volume of the saline solution 0, 5, and 10 mL. Dynamic CT scanning was performed at the hepatic hilum level. The maximum contrast enhancement, time to maximum enhancement, and time to equilibrium phase were calculated from the time attenuation curves. Mean attenuation values for all groups were measured in the aorta, portal vein, and liver. After contrast enhancement, grading of image quality regarding surrounding artifacts and evaluation of the hepatic hilum structures was performed. For comparison of the effect of the contrast material and saline solution doses, differences in mean attenuation values between the contrast medium 2 mL/kg without saline flush group and the remaining groups, and between contrast medium 3 mL/kg without saline flush group and the remaining groups, were analyzed for statistical significance. There were no significant differences between with and without saline flushing at the same contrast medium dose groups. There were no significant differences in peak values between the 3 mL/kg dose of contrast medium alone and the 2 mL/kg dose of contrast medium with saline solution flush. However, there was a significant difference in peak values between the 3 mL/kg dose of the contrast medium without the saline flush group and the 2 mL/kg dose of the contrast medium alone group. Grades of the artifacts were not significantly different in the saline flush regardless of the dose of the contrast medium. Using 2 mL/kg of contrast medium with saline solution flush resulted in similar liver parenchyma attenuation, compared with using 3 mL/kg of contrast medium without saline solution flush. In CT evaluation of hepatic parenchymal diseases, using 2 mL/kg of contrast medium with saline solution flush may yield decreased risk of contrast nephropathy and cost-saving.

• Journal of Radiation Protection and Research
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• v.14 no.1
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• pp.24-33
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• 1989

The peripheral dose, defined as the dose outside therapeutic photon fields, was estimated for 6MV X-ray linear accelerator. The measurements were performed using silicon diode detectors controlled by automatic controlled water phantom. The effects of field size, collimator position, presence or absence of wedge filter, and wedge angle were analyzed. The results were as follows 1. The peripheral dose decreases as the distance from field margin increases and it is more than 2.4% of central axis maximum dose even at 15cm distance from field margin. 2. Maximum build-up of peripheral dose is at 2-3 mm from the water surface and drops to a minimum at 1.5cm depth and then the dose increase again. 3. The peripheral dose increases as the field size. increases. At the short distance from field margin, the difference of peripheral dose between 5 $\times\;5cm^2$ and 20 $\times\;20cm^2$ field size reaches more than 2 fold. 4. The peripheral dose is higher along the upper collimator than along the lower collimator. The differences is less than 1%. 5. The presence of wedge filter increases peripheral dose. And the peripheral dose is higher along the blade side of wedge filter than along the ridge side. The difference is about 3% at 5cm distance from the field margin for 15 $\times\;15cm^2$ field size and 60$^{\circ}$ wedge filter. 6. The Peripheral dose of wedge filter increases as the wedge filter angle increases and the increasing ratio is about 2 fold in 60$^{\circ}$wedge filter compared with open field.

• The Journal of Korean Society for Radiation Therapy
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• v.34
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• pp.13-20
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• 2022

Purpose : IMRT using Tomotherapy during nasopharyngeal cancer radiation therapy irradiate an accurate dose to tumor tissues and is effective to reduce a dose rapidly in normal tissues. However, this has high MU and long Beam On Time. This study aims to analyze differences in tumors, normal tissues and low-dose distributions and the efficiency of Split VMAT after applying Helical IMRT (Tomotherapy), VMAT (Linac : 2Arc) and Split VMAT (Linac : 4Arc) plans. Materials and Methods : This study targeted ten nasopharyngeal cancer patients of this hospital and compared three treatment plans (Helical IMRT, VMAT, Split VMAT). For Helical IMRT planning, Precision^® (Version 1.1.1.1, Accuray, USA) was used, and for VMAT and Split VMAT planning, Pinnacle^3® (Version 9.10, Philips, USA) was used. The total dose applied was 38.4 Gy / 32 Gy (Daily Dose 2.4 Gy (GTV + 0.3 cm) / 2 Gy (CTV + 0.3 cm) 16Fx), and for GTV + 0.3 cm (P_GTV), 95% of V_38.4Gy was prescribed. VMAT with an angle of 360° 2Arc was applied, and for Split VMAT, the field was divided into the right, the left, the top and the bottom and an angle of 360° 4Arc, 6MV was set. For evaluating the quality of the treatment plans, differences in tumors, normal tissues and low-dose area were compared, and Beam On Time was measured to analyze the efficiency. Results : When calculating the mean values of evaluation items of the three treatment plans (Helical IMRT, VMAT, Split VMAT) for the patients, the H.I (Homogeneity Index) of P_GTV was 1.04, 1.11 and 1.1 respectively, and the C.I (Confomity Index) of P_CTV was 1.03, 0.99 and 1.00 respectively. The mean dose of RT Parotid Gland (Gy) was 14.54, 17.06 and 14.76 respectively, the mean dose of LT Parotid Gland (Gy) was 14.32, 17.32 and 15.09 respectively, the maximum dose of P_Cord (Spinal Cord + 0.3 cm) (Gy) was 20.57, 22.59 and 21.06 respectively, and the maximum dose of Brain Stem (Gy) was 22.35, 23.99 and 21.68 respectively. The 50% isodose curve (cc) was 1332, 1132.5 and 1065.2 respectively. Beam On Time (sec) was 373.7, 130.7 and 254.4 respectively. Conclusion : Displaying a similar treatment plan quality to Helical IMRT, which is used a lot for head and neck treatment, Split VMAT reduced the low-dose area and Beam On Time and produced a better result than VMAT. Therefore, it is considered that Split VMAT is effective not only for nasopharyngeal cancer but also for other head and neck cancers.