• Progress in Medical Physics
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• v.15 no.1
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• pp.1-8
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• 2004

Patient dose verification is one of the most Important responsibilities of the physician in the treatment delivery of radiation therapy. For the task, it is necessary to use an accurate dosimeter that can verify the patient dose profile, and it is also necessary to determine the physical characteristics of beams used in intensity modulated radiation therapy (IMRT) The Beam Intensity Scanner (BInS) System is presented for the dosimetric verification of the two dimensional photon beam. The BInS has a scintillator, made of phosphor Terbium-doped Gadolinium Oxysulphide (Gd$_2$O$_2$S:Tb), to produce fluorescence from the irradiation of photon and electron beams. These fluoroscopic signals are collected and digitized by a digital video camera (DVC) and then processed by custom made software to express the relative dose profile in a 3 dimensional (3D) plot. As an application of the BInS, measurements related to IWRT are made and presented in this work. Using a static multileaf collimator (SMLC) technique, the intensity modulated beam (IMB) is delivered via a sequence of static portals made by controlled leaves. Thus, when static subfields are generated by a sequence of abutting portals, the penumbras and scattered photons of the delivered beams overlap in abutting field regions and this results in the creation of “hot spots”. Using the BInS, inter-step “hot spots” inherent in SMLC are measured and an empirical method to remove them is proposed. Another major MLC technique in IMRT, the dynamic multileaf collimator (DMLC) technique, has different characteristics from SMLC due to a different leaf operation mechanism during the irradiation of photon and electron beams. By using the BInS, the actual delivered doses by SMLC and DMLC techniques are measured and compared. Even if the planned dose to a target volume is equal in our experimental setting, the actual delivered dose by DMLC technique is measured to be larger by 14.8% than that by SMLC, and this is due to scattered photons and contaminant electrons at d$_{max}$.

• Korean Journal of Environmental Agriculture
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• v.23 no.1
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• pp.52-58
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• 2004

This work was conducted to provide the reference data of radioactivity in the foodstuffs at a radiological emergency situation in Jeju Island The sampled foodstuffs were agricultural (31), livestock (6), marine (12) and forest products (4), and processed foods (3) consumed by Jeju Islanders. $^{137}Cs$ and $^{40}K$ activities were determined by HPGe r-ray spectromety. The activity ranges of $^{137}Cs$ was ${\sim}650\;mBq/kg$ fresh in the agricultural products, ${\sim}131\;mBq/kg$. fresh in the livestock, ${\sim}834\;mBq/kg$ fresh in the forest, ${\sim}253\;mBq/kg$ fresh in the marine and $32.0{\sim}483\;mBq/kg$. fresh in the processed foods (tea). In case of $^{40}K$ the activity was $16.6{\sim}542\;Bq/kg$. fresh in the agricultural products, $39.1{\sim}294\;Bq/kg$ fresh in the livestock, $85.5{\sim}116\;Bq/kg$ fresh in the forest, $50.1{\sim}657\;Bq/kg$ fresh in the marine, and $33.6{\sim}1,065\;Bq/kg$ fresh in the processed foods (tea). The highest activity of $^{137}Cs$, 834mBq/kg fresh was observed in oak mushroom and $^{40}K$ 1,065 Bq/kg fresh in coffee. Annual effective doses of $^{137}Cs$ and $^{40}K$ by intake of foodstuffs per capita were the following order; agricultural products (66,543 nSv) > livestock products (19,311 nSv) > processed foods (6,648 nSv) > marine products (6,579 nSv) > forest products (860 nSv). Therefore, total annual effective dose was summed 99,941 nSv which is quite low level comparing to the annual effective dose by external exposure, 2,400,000 nSv. The data obtained in this study can be useful for monitoring whether the foodstuffs are contaminated or not at an emergency radiation accident, and showed that the foodstuffs consumed in Jeju are safe in terms of annual effective dose of $^{137}Cs$ and $^{40}K$

• Journal of radiological science and technology
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• v.40 no.1
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• pp.41-47
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• 2017

Considering that the X-ray apron used in the department of radiology is also used in the department of nuclear medicine, the study aimed to analyze the shielding rate of the apron according to types of radioisotopes, thus ${\gamma}$ ray energy, to investigate the protective effects. The radioisotopes used in the experiment were the top 5 nuclides in usage statistics $^{99m}Tc$, $^{18}F$, $^{131}I$, $^{123}I$, and $^{201}Tl$, and the aprons were lead equivalent 0.35 mmPb aprons currently under use in the department of nuclear medicine. As a result of experiments, average shielding rates of aprons were $^{99m}Tc$ 31.59%, $^{201}Tl$ 68.42%, and $^{123}I$ 76.63%. When using an apron, the shielding rate of $^{131}I$ actually resulted in average dose rate increase of 33.72%, and $^{18}F$ showed an average shielding rate of -0.315%, showing there was almost no shielding effect. As a result, the radioisotopes with higher shielding rate of apron was in the descending order of $^{123}I$, $^{201}Tl$, $^{99m}Tc$, $^{18}F$, $^{131}I$. Currently, aprons used in the nuclear medicine laboratory are general X-ray aprons, and it is thought that it is not appropriate for nuclear medicine environment that utilizes ${\gamma}$ rays. Therefore, development of nuclear medicine exclusive aprons suitable for the characteristics of radioisotopes is required in consideration of effective radiation protection and work efficiency of radiation workers.

• Applied Biological Chemistry
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• v.14 no.3
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• pp.213-220
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• 1971

In order to investigate chemical components of edible marine algae in Korea, the present work is carried out with ten edible and two non-edible species of brown algae, collected from Cheju-island during October, 28-30 in 1970. Among the general components, water content is about 14-16% to dry weight and the crude protein about 16%, which are almost similar in content compared with several non-cultivate edible land plants. The content of crude fat is about 0.7-2.0%, and that of crude fiber about 3-8%, while the content of crude ash is 9.17-16.89%. The last one is more than two times in content compared with the land plants. The reducing sugar is about 0.27-2.49% in general. On the other hand, among the minerals Ca content is the most abundant, 1.73-2.51%, and the next is S, 1.0-1.8%. Mg and I are around 0.1-1%, while K and Na are about 1% in content. Among the micro-elements, Fe and Zn are about 0.01-0.03%, and Cu and Mn 0.001-0.005% in content. There is no special significant difference in chemical components between the edible and non-edible species of brown algae. Moreover, so far as the present investigation is concerned, there can be found no significant inter-species relationship on the taxonomical or phylogenetical points of view, considering their components.

• Journal of radiological science and technology
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• v.36 no.2
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• pp.99-110
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• 2013

In the medical field, the necessity of education growth for the professional Radiation Technologists has been emphasized to become experts on radiation and the radiation field is important of the society. Also, in hospitals and companies, important on thesis is getting higher in order to active and cope with rapidly changing internal and external environment and a more in-depth expert training, the necessity of new teaching and learning model that can cope with changes in a more proactive has become. Thesis writing classes brought limits to the in-depth learning as to start a semester and rely on only specific programs besides, inevitable on passive participation. In addition, it does not have a variety opportunity to present, an actual opportunity that can be written and discussed does not provide much caused by instructor-led classes. As well as, it has had a direct impact on the quality of the thesis, furthermore, having the opportunity to participate in various conferences showed the limitations. In order to solve these problems, in this study, writing thesis has organized training operations as a consistent gradual deepening of learning, at the same time, the operational idea was proposed based on the connectivity integrated operating and effective training program & instructional tool for improving the ability to perform the written actual thesis. The development of teaching and learning model consisted of 4 system modeling, scaffolding, articulation, exploration. Depending on the nature of the course, consisting team following the personal interest and the topic allow for connection subject, based on this, promote research capacity through a step-by-step evaluation and feedback and, fundamentally strengthen problem-solving skills through the journal studies, help not only solving the real-time problem by taking wiki-space but also efficient use of time, increase the quality of the thesis by activating cooperation through mentoring, as a result, it was to promote a positive partnership with the academic. Support system in three stages planning subject, progress & writing, writing thesis & presentation and based on cognitive apprenticeship. The ongoing Coaching and Reflection of professor and expert was applied in order to maintain these activities smoothly. The results of this study will introduce actively, voluntarily and substantially join to learners, by doing so, culture the enhancement of creativity, originality and the ability to co-work and by enhance the expertise of based-knowledge, it is considered to be help to improve the comprehensive ability.

• Journal of the Korean Society of Radiology
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• v.15 no.5
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• pp.667-673
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• 2021

As we enter the era of the 4th industrial revolution, it is judged that the scope of work of radiologists will be further expanded according to the innovation and advancement of radiation medical technology development. In this study, the current status of medical equipment and radiology technicians was identified, and basic data were provided for the plan for nurturing talents in the field of radiation medical technology in the era of the 4th industrial revolution, as well as career and employment counseling. Data from the second quarter of 2020 and the second quarter of 2021 were analyzed using health and medical big data. As a result of comparing the status of medical equipment by type in 2021 compared to 2020, C-Arm X-ray examination equipment increased by 5.83% to 6,638 units, followed by MRI examination equipment 1,811 units 5.29%, and angiography equipment 725 units 5.22% , general X-ray examination equipment 21,557 units increased 3.99%, CT examination equipment 2,136 units 3.03%, and breast examination equipment 3,425 units increased 3.00%. As a result of a comparison of the total number of radiologists in 2021 compared to 2020, the number was 29,038, an increase of 2.73%. As a result of comparing the status of radiographers by region, the increase was highest in the Gyeonggi region with 5.96%, followed by the Gangwon region with a 5.66% increase and the Chungnam region with a 3.81% increase. In a situation where the number of medical equipment and radiologist manpower is increasing, universities are developing specialized knowledge and practical competency through subject development related to the understanding and utilization of customized artificial intelligence and big data that can be applied in the medical radiation technology field in the era of the 4th industrial revolution. It is necessary to nurture qualified radiographers, and at the level of the association, it is thought that active policies are needed to create new jobs and improve employment.

• Journal of Gastric Cancer
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• v.23 no.1
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• pp.3-106
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• 2023

Gastric cancer is one of the most common cancers in Korea and the world. Since 2004, this is the 4th gastric cancer guideline published in Korea which is the revised version of previous evidence-based approach in 2018. Current guideline is a collaborative work of the interdisciplinary working group including experts in the field of gastric surgery, gastroenterology, endoscopy, medical oncology, abdominal radiology, pathology, nuclear medicine, radiation oncology and guideline development methodology. Total of 33 key questions were updated or proposed after a collaborative review by the working group and 40 statements were developed according to the systematic review using the MEDLINE, Embase, Cochrane Library and KoreaMed database. The level of evidence and the grading of recommendations were categorized according to the Grading of Recommendations, Assessment, Development and Evaluation proposition. Evidence level, benefit, harm, and clinical applicability was considered as the significant factors for recommendation. The working group reviewed recommendations and discussed for consensus. In the earlier part, general consideration discusses screening, diagnosis and staging of endoscopy, pathology, radiology, and nuclear medicine. Flowchart is depicted with statements which is supported by meta-analysis and references. Since clinical trial and systematic review was not suitable for postoperative oncologic and nutritional follow-up, working group agreed to conduct a nationwide survey investigating the clinical practice of all tertiary or general hospitals in Korea. The purpose of this survey was to provide baseline information on follow up. Herein we present a multidisciplinary-evidence based gastric cancer guideline.

• Progress in Medical Physics
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• v.26 no.3
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• pp.160-167
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• 2015

Radiation exposure from medical diagnostic imaging procedures to patients is one of the most significant interests in diagnostic x-ray system. A miniature x-ray intraoral tube was developed for the first time in the world which can be inserted into the mouth for imaging. Dose evaluation should be carried out in order to utilize such an imaging device for clinical use. In this study, dose evaluation of the new x-ray unit was performed by 1) using a custom made in vivo Pig phantom, 2) determining exposure condition for the clinical use, and 3) measuring patient dose of the new system. On the basis of DRLs (Diagnostic Reference Level) recommended by KDFA (Korea Food & Drug Administration), the ESD (Entrance Skin Dose) and DAP (Dose Area Product) measurements for the new x-ray imaging device were designed and measured. The maximum voltage and current of the x-ray tubes used in this study were 55 kVp, and 300 mA. The active area of the detector was $72{\times}72mm$ with pixel size of $48{\mu}m$. To obtain the operating condition of the new system, pig jaw phantom images showing major tooth-associated tissues, such as clown, pulp cavity were acquired at 1 frame/sec. Changing the beam currents 20 to $80{\mu}A$, x-ray images of 50 frames were obtained for one beam current with optimum x-ray exposure setting. Pig jaw phantom images were acquired from two commercial x-ray imaging units and compared to the new x-ray device: CS 2100, Carestream Dental LLC and EXARO, HIOSSEN, Inc. Their exposure conditions were 60 kV, 7 mA, and 60 kV, 2 mA, respectively. Comparing the new x-ray device and conventional x-ray imaging units, images of the new x-ray device around teeth and their neighboring tissues turn out to be better in spite of its small x-ray field size. ESD of the new x-ray device was measured 1.369 mGy on the beam condition for the best image quality, 0.051 mAs, which is much less than DRLs recommended by IAEA (International Atomic Energy Agency) and KDFA, both. Its dose distribution in the x-ray field size was observed to be uniform with standard deviation of 5~10 %. DAP of the new x-ray device was $82.4mGy*cm^2$ less than DRL established by KDFA even though its x-ray field size was small. This study shows that the new x-ray imaging device offers better in image quality and lower radiation dose compared to the conventional intraoral units. In additions, methods and know-how for studies in x-ray features could be accumulated from this work.

• Journal of Radiation Protection and Research
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• v.6 no.1
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• pp.25-30
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• 1981

A measurement has been made for the radioactivities (or concentrations) of radon daughters, i.e., RaA, RaB and RaC in airborne dust by means of single filtering method. This is to evaluate the radioactivities in terms of Ci or WL (working level) from gross alpha counts measured in the selected-time intervals after an air sample is taken from a membrane filter paper with a mean pore size of $0.8{\mu}m$. This work involves determinations of standard deviation in radioactivities, radioactive equilibrium factor and ratio. It appears that a concentration of total radon daughters is $0.30{\sim}2.36pCi/l\;or\;0.89{\times}10^{-3}{\sim}6.57{\times}10^{-3}WL$, depending on the sampling time. Generally the highest concentration was observed around nine o'clock in a day while the lowest value was obtained around seventeen o'clock. Standard deviations based on counting statistics of RaA's, RaB's and RaC's concentrations are ${\pm}57.75%,\;{\pm}22.32%\;and\;{\pm}31.29%$, respectively. It is revealed that the radioactive equilibrium factor is 0.322 while the radioactive equilibrium ratio is of pattern $C_1>C_2>C_3$ in general. Here $C_1,\;C_2\;and\;C_3$ stand for concentrations of RaA,RaB and RaC, respectively.

• Journal of the Korean Society of Radiology
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• v.5 no.2
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• pp.93-96
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• 2011

Currently, the development of direct conversion radiation detector using photoconductor materials is progressing in widely. Among of theses photoconductor materials, mercuric iodide compound than amorphous selenium has excellent absorption and sensitivity of high energy radiation. Also, the detection efficiency of signal generated in photoconductor film varies by electric filed and geometric distribution according to top-bottom electrode size. Therefore, in this work, the x-ray detection characteristics are investigated about the size of top electrode in $HgI_2$ photoconductor film. For sample fabrication, to solve the problem that is difficult to make a large area film, we used the spatial paste screen-print method. And the sample thickness is $150{\mu}m$ and an film area size is $3cm{\times}3cm$ on ITO-coated glass substrate. ITO(Indium-Tin-Oxide) electrode was used as top electrode using a magnetron sputtering system and each area is $3cm{\times}3cm$, $2cm{\times}2cm$ and $1cm{\times}1cm$. From experimental measurement, the dark current, sensitivity and SNR of the $HgI_2$ film are obtained from I-V test. From the experimental results, it shows that the sensitivity increases in accordance with the area of the electrode but the SNR is decreased because of the high dark current. Therefore, the optimized size of electrode is importance for the development of photoconductor based x-ray imaging detector.