• Progress in Medical Physics
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• v.26 no.1
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• pp.12-17
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• 2015

The purpose of the Monte Carlo simulation study was to provide the optimized nozzle design to satisfy the beam conditions for biomedical researches in the Korean heavy-ion accelerator, RAON. The nozzle design was required to produce $C^{12}$ beam satisfying the three conditions; the maximum field size, the dose uniformity and the beam contamination. We employed the GEANT4 toolkit in Monte Carlo simulation to optimize the nozzle design. The beams for biomedical researches were required that the maximum field size should be more than $15{\times}15cm^2$, the dose uniformity was to be less than 3% and the level of beam contamination due to the scattered radiation from collimation systems was less than 5% of total dose. For the field size, we optimized the tilting angle of the circularly rotating beam controlled by a pair of dipole magnets at the most upstream of the user beam line unit and the thickness of the scatter plate located downstream of the dipole magnets. The values of beam scanning angle and the thickness of the scatter plate could be successfully optimized to be $0.5^{\circ}$ and 0.05 cm via this Monte Carlo simulation analysis. For the dose uniformity and the beam contamination, we introduced the new beam configuration technique by the combination of scanning and static beams. With the combination of a central static beam and a circularly rotating beam with the tilting angle of $0.5^{\circ}$ to beam axis, the dose uniformity could be established to be 1.1% in $15{\times}15cm^2$ sized maximum field. For the beam contamination, it was determined by the ratio of the absorbed doses delivered by $C^{12}$ ion and other particles. The level of the beam contamination could be achieved to be less than 2.5% of total dose in the region from 5 cm to 17 cm water equivalent depth in the combined beam configuration. Based on the results, we could establish the optimized nozzle design satisfying the beam conditions which were required for biomedical researches.

• Molecules and Cells
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• v.27 no.5
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• pp.591-599
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• 2009

Nicotinic acetylcholine receptors (nAChRs) play important roles in nervous system functions and are involved in a variety of diseases. We previously demonstrated that ginsenosides, the active ingredients of Panax ginseng, inhibit subsets of nAChR channel currents, but not ${\alpha}7$, expressed in Xenopus laevis oocytes. Mutation of the highly conserved Leu247 to Thr247 in the transmembrane domain 2 (TM2) channel pore region of ${\alpha}7$ nAChR induces alterations in channel gating properties and converts ${\alpha}7$ nAChR antagonists into agonists. In the present study, we assessed how point mutations in the Leu247 residue leading to various amino acids affect 20(S)-ginsenoside $Rg_3$ ($Rg_3$) activity against the ${\alpha}7$ nAChR. Mutation of L247 to L247A, L247D, L247E, L247I, L247S, and L247T, but not L247K, rendered mutant receptors sensitive to $Rg_3$. We further characterized $Rg_3$ regulation of L247T receptors. We found that $Rg_3$ inhibition of mutant ${\alpha}7$ nAChR channel currents was reversible and concentration-dependent. $Rg_3$ inhibition was strongly voltage-dependent and noncompetitive manner. These results indicate that the interaction between $Rg_3$ and mutant receptors might differ from its interaction with the wild-type receptor. To identify differences in $Rg_3$ interactions between wild-type and L247T receptors, we utilized docked modeling. This modeling revealed that $Rg_3$ forms hydrogen bonds with amino acids, such as Ser240 of subunit I and Thr244 of subunit II and V at the channel pore, whereas $Rg_3$ localizes at the interface of the two wild-type receptor subunits. These results indicate that mutation of Leu247 to Thr247 induces conformational changes in the wild-type receptor and provides a binding pocket for $Rg_3$ at the channel pore.

• Radiation Oncology Journal
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• v.10 no.2
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• pp.171-180
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• 1992

The precise role of radiotherapy for low grade gliomas including the optimal radiation dose and timing of treatment remains unclear. The information given by a retrosepctive analysis may be useful in the design of prospective randomized studies looking at radiation dose and time of surgical and radiotherapeutic treatment. The records of 56 patients (M:F = 29:27) with histologically verified cerebral low grade gliomas (47 cases of grade 1 or 2 astrocytomas and 9 oligodendrogliomas) diagnosed between 1979 and 1989 were retrospectively reviewed. The extent of surgical tumor removal was gross total or radical subtotal in 38 patients ($68\%$) and partial or biopsy only in the remaining 18 patients ($32\%$). Postooperative radiation therapy was given to 36 patients ($64\%$) of the total 56 patients with minimum dose of 5000 cGy (range=1250 to 7220 cGy). The 5-and 10-year survival rates for the total 56 patients were $44\%$ and $32\%$ respectively with a median survival of 4.1 years. According to the histologic grade the 5- and 10-year survivals were $52\%$ and $35\%$ for the 24 patients respectively with grade I astrocytomas compared to $20\%$ and $10\%$ for the 23 patients with grade II astrocytomas. Survival of oligodendroglioma patients was greater than those with astrocytoma ($65\%$ vs $36\%$ at 5 years), and the difference was also remarkable in the long term period of follow up ($54\%$ vs $23\%$ at 10 years). Those who received high-dose radiation therapy ($\geq$5400 cGy) had significant better survival than those who received low-dose radiation (< 5400cGy) or surgery alone (p<0.05). The 5- and 10-year survival rates were, respectively $59\%$ and $46\%$ for the 23 patients receiving high-dose radiation, $36\%$ and $24\%$ for the 13 patients receiving low-dose radiation, and $35\%$ and $26\%$ for the 20 patients with surgery alone. Survival rates by the extent of surgical resection were similar at 5 years ($46\%$ vs $41\%$), but long term survival was quite different (p<0.01) between total/subtotal resection and partial resection/biopsy ($41\%$ and $12\%$, resepctively). Previously published studies have identified important prognostic factors in these tumor: age, extent of surgery, grade, performance status, and duration of symptoms. But in our cases statistical analysis revealed that grade I histology (p<0.025) and young age (p<0.001) were the most significant good prognostic variables.

• Journal of the Korean Society of Radiology
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• v.7 no.2
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• pp.145-149
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• 2013

Helical Tomotherapy is an innovative means of delivering intensity modulated radiation therapy (IMRT) using a device that merges features of a linear accelerator and helical computed tomography (CT) scanner. Hereat, during helical tomotherapy process, megavoltage computed tomography (MVCT) image are usually used for guiding the precise set-up of patient before/after treatment delivery. But which would certainly increase the total dose for patients, this study was to investigate the imaging dose of MVCT using the cylindrical "Cheese" phantom on a tomotherapy machine. A set of cylindrical "Cheese" phantom was adopted for scanning with respectively pitch value (1, 2, 3 mm) with same number slice (10 slice), same length (approximately 9 cm) and phantom set-ups on the couch of tomotherapy system. The average MVCT imaging dose were measured using A1SL ion chamber inserted in the phantom with preset geometry. The MVCT scanning average dose for the cylindrical "Cheese" phantom was 2.24 cGy, 1.02 cGy, 0.81 cGy during respectively pitch value (pitch 1, 2, 3 mm) with same number slice (10 slice), and same length's average dose was 2.47 cGy, 1.28 cGy, 0.88 cGy respectively (pitch 1, 2, 3 mm). Two major parameters, the assigned pitch numbers and scanning length, where the most important impacts to the dose variation. The MVCT dose was inversely proportional to the CT pitch value. The results may provide a reliable guidance for proper planning design of the scanning region, which is valuable to help minimize the extra dose to patient. Questionnaires were distributed to Radiology departments at hospitals with 300 sickbeds throughout the Pohang region of North Gyeongsang Province concerning awareness and performance levels of infection control. The investigation included measurements of the pollution levels of imaging equipment and assistive apparatuses in order to prepare a plan for the activation of prevention and management of hospital infections. The survey was designed to question respondents in regards to personal data, infection management prevention education, and infection management guidelines.

• The Journal of Korean Society for Radiation Therapy
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• v.18 no.2
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• pp.81-87
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• 2006

Purpose: Few researches have been peformed on the dose distribution of the moving organ for radiotherapy so far. In order to simulate the organ motion caused by respiratory function, multipurpose phantom and moving device was used and dosimetric measurements for dose distribution of the moving organs were conducted in this study. The purpose of our study was to evaluate how dose distributions are changed due to respiratory motion. Materials and Methods: A multipurpose phantom and a moving device were developed for the measurement of the dose distribution of the moving organ due to respiratory function. Acryl chosen design of the phantom was considered the most obvious choice for phantom material. For construction of the phantom, we used acryl and cork with density of $1.14g/cm^3,\;0.32g/cm^3$ respectively. Acryl and cork slab in the phantom were used to simulate the normal organ and lung respectively. The moving phantom system was composed of moving device, moving control system, and acryl and cork phantom. Gafchromic film and EDR2 film were used to measure dose ditrbutions. The moving device system may be driven by two directional step motors and able to perform 2 dimensional movements (x, z axis), but only 1 dimensional movement(z axis) was used for this study. Results: Larger penumbra was shown in the cork phantom than in the acryl phantom. The dose profile and isodose curve of Gafchromic EBT film were not uniform since the film has small optical density responding to the dose. As the organ motion was increased, the blurrings in penumbra, flatness, and symmetry were increased. Most of measurements of dose distrbutions, Gafchromic EBT film has poor flatness and symmetry than EDR2 film, but both penumbra distributions were more or less comparable. Conclusion: The Gafchromic EBT film is more useful as it does not need development and more radiation dose could be exposed than EDR2 film without losing film characteristics. But as response of the optical density of Gafchromic EBT film to dose is low, beam profiles have more fluctuation at Gafchromic EBT. If the multipurpose phantom and moving device are used for treatment Q.A, and its corrections are made, treatment quality should be improved for the moving organs.

• The Journal of Korean Society for Radiation Therapy
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• v.27 no.1
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• pp.87-95
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• 2015

Purpose : This study presents the usefulness assessment of secondary shield for the lens exposure dose reduction during radiation treatment of peripheral orbit. Materials and Methods : We accomplished IMRT treatment plan similar with a real one through the computed treatment planning system after CT simulation using human phantom. For the secondary shield, we used Pb plate (thickness 3mm, diameter 25mm) and 3 mm tungsten eye-shield block. And we compared lens dose using OSLD between on TPS and on simulation. Also, we irradiated 200 MU(6 MV, SPD(Source to Phantom Distance)=100 cm, $F{\cdot}S\;5{\times}5cm$) on a 5cm acrylic phantom using the secondary shielding material of same condition, 3mm Pb and tungsten eye-shield block. And we carried out the same experiment using 8cm Pb block to limit effect of leakage & transmitted radiation out of irradiation field. We attached OSLD with a 1cm away from the field at the side of phantom and applied a 3mm bolus equivalent to the thickness of eyelid. Results : Using human phantom, the Lens dose on IMRT treatment plan is 315.9cGy and the real measurement value is 216.7cGy. And after secondary shield using 3mm Pb plate and tungsten eye-shield block, each lens dose is 234.3, 224.1 cGy. The result of a experiment using acrylic phantom, each value is 5.24, 5.42 and 5.39 cGy in case of no block, 3mm Pb plate and tungsten eye-shield block. Applying O.S.B out of the field, each value is 1.79, 2.00 and 2.02 cGy in case of no block, 3mm Pb plate and tungsten eye-shield block. Conclusion : When secondary shielding material is used to protect critical organ while irradiating photon, high atomic number material (like metal) that is near by critical organ can be cause of dose increase according to treatment region and beam direction because head leakage and collimator & MLC transmitted radiation are exist even if it's out of the field. The attempt of secondary shield for the decrease of exposure dose was meaningful, but untested attempt can have a reverse effect. So, a preliminary inspection through Q.A must be necessary.

• Radiation Oncology Journal
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• v.18 no.1
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• pp.67-72
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• 2000

Background :The authors have developed a Digital image chart(DIC) and digital Radiotherapy Record System (DRRS). We have evaluated the DIC and DRRS for reliability, usefulness, ease of use, and efficiency. Materials and Methods :The basic design of the DIC and DRRS was to build an digital image database of radiation therapy Patient records for a more efficient and timely flow of critical image information throughout the department. This system is a submit of comprehensive radiation oncology management system (C-ROMS) and composed of a picture archiving and communication system (PACS), a radiotherapy information database, and a radiotherapy imaging database. The DIC and DRRS were programmed using Delphi under a Windows 95 environment and is capable of displaying the digital images of patients identification photos, simulation films, radiotherapy setup, diagnostic radiology images, gross lesion Photos, and radiotherapy Planning isodose charts with beam arrangements. Twenty-three clients in the department are connected by Ethernet (10 Mbps) to the central image server (Sun Ultra-sparc 1 workstation). Results :From the introduction of this system in February 1998 through December 1999, we have accumulated a total of 15,732 individual images for 2,556 patients. We can organize radiation therapy in a 'paperless' environment in 120 patients with breast cancer. Using this system, we have succeeded in the prompt, accurate, and simultaneous access to patient care information from multiple locations throughout the department. This coordination has resulted in improved operational efficiency within the department. Conclusion :The authors believe that the DIC and DRRS has contributed to the improvement of radiation oncology department efficacy as well as to time and resource savings by providing necessary visual information throughout the department conveniently and simultaneously. As a result, we can also achieve the 'paperless' and 'filmless' practice of radiation oncology with this system.

• Journal of East-West Nursing Research
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• v.5 no.1
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• pp.90-101
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• 2000

The study attempts to examine the degree of cognition and demand on health promotion center of oriental nursing. It puts unique nursing intervention using traditional health promotion connected with oriental medicine to practical use for residents' health promotion and prevention of disease. With the study design of cross-sectional descriptive study, 516 residents who live in 26 Dongs, Dongdaemoon-gu were selected. The tool of study consists of 30 questions which the study team made for the degree of cognition and demand on health promotion center of oriental nursing. Cronbach's $\alpha$ in the degree of cognition was .8028. Collection of research data had been done from October 1 to October 30, 1999 with help of Dongdaemoon-gu office after pretest from 20 residents. Collected data were analyzed into the number and percentage in the characteristic of a subject and connected with demand on the establishment of center, the mean and the standard deviation in the degree of cognition and F-tests in the difference of the degree of cognition by characteristics. The results were as follow; 1) The characteristic of subject of this study was male 50.6%, and average age was 38.5 years old and 30-39 years old occupied the highest percentage with 31.6%. The married were 71.8%, over high school graduates was 85.6%, monthly income from 500 thousand won to 2 million won was 86.1%. 50.8% was the type living with parents, children and sibling. 2) When they were sick, the institution which residents used at first was a pharmacy(69.2%) and hospital(27.5%), but oriental medicine hospital was just 1.4%. As for subjective health condition, 82.5% answered over average, and 28.7% answered that they had chronic illness such as arthritis, chronic digestion problem, hypertension and so on. As for information collection on health, mass communication(34.9%) and medically concerned people(28.1%) occupied relatively high rate. Free health diagnosis system(36.8%) and establishment of health promotion center(31.5%) among welfare programs that residents want to enjoy were high ranked. The rate using a special institution for health was 17.8%, and among these institutions, the rate using aerobic exercises, health center(7.0%) and steamed room(5.4%) was high. Besides, other institutions such as breathing at the abdomen, finger-pressure therapy, meridian massage, foot massage, and so on were being used. 3) As the average of the degree of cognition on health promotion center of oriental medicine was 2.92, the degree of cognition was medium. The description, "health promotion center of oriental medicine is necessary for health keeping of healthy people, including people who have a problem in health" showed the highest degree of cognition(3.04, ${\pm}0.64$). 4) As for the intention on using health promotion center of oriental nursing, 61.4% said "yes", "no" was just 1.4%. The services that people relatively high wanted to be served from the center were measures reducing stress(68.0%) (relaxation therapy, meditation, breathing at the abdomen and so on), acupuncture(66.5%), finger-pressure(61.6%), moxibustion(57.6%), meridian massage(44.2%), postpartum care(40.3%) and so on. 5) As for the degree of cognition on the establishment of health promotion center of oriental nursing by characteristics of subject, there was significant difference(F=4.03, p=.046) between male(3.01) and female(2.91). But there was no significant difference by age, marital status, level of educational achievement and monthly income. As the above result, cognition on the establishment of health promotion center of oriental nursing was relatively low because people were not familiar with about the health promotion center of oriental nursing yet. However once the center will be established, the degree of demand on the center will be relatively high. So positive advertisement will be necessary, and the management of useful programs will be also required in order to make people recognize the advantage when they actually will use the center. On the other hand, as the subject of the study consists of many young people of below 30, the health problem came to be low. And in the case of sampling, the study using random sampling that can represent population will be required.

• Journal of the Korean Society of Radiology
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• v.6 no.3
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• pp.207-215
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• 2012

As one of photo dynamic therapies, the existing LED photo irradiation method with 635 nm continuous wave has most frequently been used for acne treatment, it suffered from a low energy efficiency and generation of a large amount of heat in tissues requiring improvement measures. In this thesis, a LED photo irradiation system for acne treatment has been designed using PWM(Pulse Width Modulation) mode to enhance the energy efficiency and prevent thermal destruction in tissues. System configuration consisting largely of timer module, PWM module, and photo transfer device has been designed with the use of 1 W LED at a wavelength of 660 nm for the photo transfer device to increase skin penetration depth for treatment of acne. Frequency and wave form generated by using PWM control was verified along with confirmation of output energy of 660 nm LED and surface temperatures of tissues, followed by evaluation of stable energy outputs and stability of tissues. The results indicated that whereas power loss was high and thermal destruction in tissues was exhibited when C.W mode was used to obtain the optical energy of 1 W LED at a wavelength of 660 nm for acne treatment, realization of PWM mode allowed lowering of power consumption for LED through pulse width modulation, and no occurrence of thermal destruction in tissues, suggesting that PWM mode is safer and more effective for treatment of acne than C.W mode.

• Journal of the Korean Society of Radiology
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• v.7 no.1
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• pp.9-15
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• 2013

In this study, texture feature analysis (TFA) algorithm to automatic recognition of liver disease suggests by utilizing computed tomography (CT), by applying the algorithm computer-aided diagnosis (CAD) of hepatocellular carcinoma (HCC) design. Proposed the performance of each algorithm was to comparison and evaluation. In the HCC image, set up region of analysis (ROA, window size was $40{\times}40$ pixels) and by calculating the figures for TFA algorithm of the six parameters (average gray level, average contrast, measure of smoothness, skewness, measure of uniformity, entropy) HCC recognition rate were calculated. As a result, TFA was found to be significant as a measure of HCC recognition rate. Measure of uniformity was the most recognition. Average contrast, measure of smoothness, and skewness were relatively high, and average gray level, entropy showed a relatively low recognition rate of the parameters. In this regard, showed high recognition algorithms (a maximum of 97.14%, a minimum of 82.86%) use the determining HCC imaging lesions and assist early diagnosis of clinic. If this use to therapy, the diagnostic efficiency of clinical early diagnosis better than before. Later, after add the effective and quantitative analysis, criteria research for generalized of disease recognition is needed to be considered.