• Progress in Medical Physics
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• v.27 no.4
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• pp.220-223
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• 2016

Generally, it is recommended that the dosimetric effect of carbon fiber couch should be considered especially for an intensity-modulated therapy with a large portion of monitor units from posterior angles. Even a flattening filter free (FFF) beam has been used for stereotactic body radiation therapy (SBRT), the effect of carbon fiber couch for FFF beam is not well known. This work is an effort to evaluate the dosimetric effect of carbon fiber couch for flattened and FFF beam of Elekta linac empirically. The absorbed doses were measured with Farmer type chamber and water-equivalent phantoms with and without couch. And differences of the absorbed doses between with and without couch defined as "couch effect". By comparing calculated dose in treatment planning system (TPS) with measured dose, the optimal density of couch was evaluated. Finally, differences on patient's skin dose and target dose by couch were evaluated in TPS. As a result, the couch effect for 6 and 10 MV flattened beam were -2.71% and -2.32%, respectively. These values were agreed with provided data by vendor within 0.5%. The couch effect for 6 and 10 MV FFF beam were -3.75% and -2.80%, respectively. The patient's skin dose was increased as 18.6% and target dose was decreased as 0.87%, respectively. It was realized that the couch effect of FFF beam was more severe than that of flattened beam. Patient's skin dose and target dose were changed by the couch effect.

• Radiation Oncology Journal
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• v.12 no.3
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• pp.285-293
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• 1994

Purpose : The study was designed to investigate the effect of cis-dichlorodiammineplatinum(II)(cis-DDP) on the radiation-induced cardiomyopathy in the rat. Materials and Methods : The myocardial damage was assessed by histopathologic changes. In radiation alone group, radiation dose ranged from 10-40 Gy X-ray in a single dose and in combined group, cis-dichlorodiammineplatinum(II) at a dose of 6 mg/kg was given intraperitoneally immediately after irradiation of same dose with X-ray alone group. Results : The early changes by radiation included congestion, inflammatory cell infiltrations and fibrosis in myocardial interstitium with focal myocardial necrosis, which was noted in 10 Gy group, Myocardial fibrosis was increased by increasing dose of radiation but myocardial necrosis was not Proportional to radiation dose. cis-DDP alone group showed minimal degeneration of myocardium with surrounded by inflammatory cell infiltrations. In combined group, myocardial fibrosis in 10 Gy group were similar to radiation alone group, but 30 Gy and 40 Gy groups showed severer changes. Electron microscopic examination showed disruption of Z-band and edema of mitochondria with decreased matrix density in 20 Gy radiation group which were severer in 40 Gy radiation group. Combined group showed endothelial changes and disruption of Z-band worse than radiation alone group as well as increased connective tissue, which was considered as a hallmark of late change in radiation-induced heart disease. Conclusion : This results showed minimal enhancement of the radiation-induced cardiomyopathy in rats by cis-DDP.

• Journal of Radiation Protection and Research
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• v.20 no.2
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• pp.97-102
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• 1995

Adaptive response induced by low dose ${\gamma}-ray$ irradiation in human peripheral lymphocytes was examimed. Human lymphocytes were exposured to low dose of ${\gamma}-ray$ (priming dose, 0.01Gy) followed by high dose (challenging dose, 1.5Gy) after various time intervals (4, 7, 20 hours). Frequencies of micronuclei were enumerated in both primed and unprimed groups. Maximum reduction in frequency of micronuclei was observed when challenging dose irradiation was followed by priming dose after 4hr incubation period. When challenging doses were irradiated 7 or 20hr after priming dose, frequencies of micronuclei were reduced slighty. However, these reduction were not statistically significant. In this study, human peripheral lymphocytes were irradiated at Go phase and they showed adaptive response induced by low dose radiation. Since micronucleus assay is relatively simpler and faster than other methods, it may be a good tool for evaluating radiation-induced adaptive responses.

• Asian Pacific Journal of Cancer Prevention
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• v.14 no.3
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• pp.1609-1614
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• 2013

Objective: To evaluate the effect of intravenous contrast on dose calculation in radiation treatment planning for oesophageal cancer. Methods: A total of 22 intravein-contrasted patients with oesophageal cancer were included. The Hounsfield unit (HU) value of the enhanced blood stream in thoracic great vessels and heart was overridden with 45 HU to simulate the non-contrast CT image, and 145 HU, 245 HU, 345 HU, and 445 HU to model the different contrast-enhanced scenarios. 1000 HU and -1000 HU were used to evaluate two non-physiologic extreme scenarios. Variation in dose distribution of the different scenarios was calculated to quantify the effect of contrast enhancement. Results: In the contrast-enhanced scenarios, the mean variation in dose for planning target volume (PTV) was less than 1.0%, and those for the total lung and spinal cord were less than 0.5%. When the HU value of the blood stream exceeded 245 the average variation exceeded 1.0% for the heart V40. In the non-physiologic extreme scenarios, the dose variation of PTV was less than 1.0%, while the dose calculations of the organs at risk were greater than 2.0%. Conclusions: The use of contrast agent does not significantly influence dose calculation of PTV, lung and spinal cord. However, it does have influence on dose accuracy for heart.

• The Journal of Korean Society for Radiation Therapy
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• v.9 no.1
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• pp.87-93
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• 1997

The using of compensator is required to adjust the irregular dose distribution due to irregular thickness of the body in Total Body Irradiation. Aluminuim, copper or lead is generally used as compensator. In our study, we would like to introduce a result of the attenuation and compensation effect of radiation use compensator made by duralumin and its clinical use. The thickness of compensator was calculated by the attenustion of radiation, which was measured by polystyrene phantom and ionization chamber(farmer). The compensation effect of radiation was measured by diode detector. All of conditions were set as in real treatment, and the distanc from source to detector was 446 cm. We also made fixation of device to easily attach the compensator to LINAC. Beam spoiler was menufactured and placed on the patient to irradiate sufficient dose to the skin. diode detector were placed on head, neck, chest, umbilicus. pelvis and knee with each their entranced exit points, and datas of dose distribution were evaluated and compared in each points for eleven patients(Feb. 96-Feb. 97). The attenuation rate of irradiation by duralumin compensator was measured as $1.4\%$ in 2mm thickness. The mean attenuation rate was $1.3\%$ per 2mm as increasing the thickness gradually to 50 mm. By using duralunim compensator, dose distribution in each points of body was measured with ${\pm}2.8\%$ by diode detectior. We could easily calculate the thickness of compensator by measuring the attenuation rate of radiation, remarkably reduce the irragularity of dose distribution duo to the thickness of body and magnify the effect of radiation therapy.

• 대한방사선방어학회:학술대회논문집
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• 2010.04a
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• pp.148-149
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• 2010

• Molecules and Cells
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• v.19 no.1
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• pp.143-148
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• 2005

Heptaplatin, cis-malonato [(4R,5R)-4,5-bis (amino-methyl)-2-isopropyl-1,3-dioxolane] platinum(II) (SKI-2053R, Sunpla) is a new platinum derivative with antitumor activity comparable to cisplatin on various cancer cell lines. Preclinical studies suggest that it is less nephrotoxic than cisplatin. This study was undertaken to examine the combined effect of heptaplatin and ionizing radiation on two established human squamous carcinoma cell lines (NCI-H520, SQ20B). The cytotoxic activity of heptaplatin was concentration-dependent in both cell lines. When low dose heptaplatin was combined with high dose ionizing radiation, there was an additive cytotoxic effect on NCI-H520 cells (P < 0.05), while a moderate dose of heptaplatin and a low dose of ionizing radiation had an additive cytotoxic effect on the growth of SQ20B cells (P < 0.05). FACS analysis and DAPI staining showed that their additive cytotoxic effects were correlated with the induction of apoptosis. Further studies are warranted using heptaplatin and ionizing radiation in squamous cell carcinoma as a substitute for cisplatin.

• ETRI Journal
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• v.27 no.4
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• pp.449-452
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• 2005

The electrical characteristics of solid state devices such as the bipolar junction transistor (BJT), metal-oxide semiconductor field-effect transistor (MOSFET), and other active devices are altered by impinging photon radiation and temperature in the space environment. In this paper, the threshold voltage, the breakdown voltage, and the on-resistance for two kinds of MOSFETs (200 V and 100 V of $V_{DSS}$) are tested for ${\gamma}-irradiation$ and compared with the electrical specifications under the pre- and post-irradiation low dose rates of 4.97 and 9.55 rad/s as well as at a maximum total dose of 30 krad. In our experiment, the ${\gamma}-radiation$ facility using a low dose, available at Korea Atomic Energy Research Institute (KAERI), has been applied on two commercially available International Rectifier (IR) products, IRFP250 and IRF540.

• The Transactions of the Korean Institute of Electrical Engineers D
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• v.54 no.9
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• pp.556-558
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• 2005

The effect of high irradiation on inspection systems in a nuclear power plant can be severe, especially to electronic components such as control hoards. The effect may lead to a critical malfunction or trouble to a underwater robot for inspection and maintenance of nuclear reactor. However, if information on the total accumulated dose on the sensitive parts of the robot is available, a prediction of robot's behavior in radiation environments becomes possible. To know how much radiation the robot has encountered, a dosimeter to measure the total accumulated dose is necessary. This paper describes the development effort of a dual radiation monitoring system using a SiC diode as a dose-rate meter and a p-type power MOSFET as a dose meter. This attempt using two sensors which detect same radiation improves reliability and stability at high intensity radiation detection in nuclear facilities. It uses the concept of diversity and redundancy.

• Journal of Radiation Protection and Research
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• v.41 no.2
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• pp.133-140
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• 2016

Backgrounds: The accident at Fukushima Daiichi Nuclear Power Plant (NPP), March 2011, caused serious radioactive contamination over wide area in east Japan. Therefore, it is important to know the effect of the accident and the status of NPP. Materials and Methods: This paper provides a review on the status of radiation dose and radioactive contamination caused by the accident on the basis of publicized information. Results and Discussion: Monitoring of radiation dose and exposure dose of residents has been conducted extensively by the governments and various organizations. The effective dose of general residents due to the accident proved to be less than a mSv both for external and internal dose. The equivalent committed dose of thyroid was evaluated to be a few mSv in mean value and less than 50 mSv even for children. Monitoring of radioactivity concentration has been carried out on food ingredients, milk and tap water, and actual meal. These studies indicated the percentage of foods above the regulation standard was over 10% in 2011 but decreasing steadily with time. The internal dose due to foods proved to be tens of ${\mu}Sv$ and much less than that due to natural $^{40}K$ even in the Fukushima area and decreasing steadily, although high level concentration is still observed in wild plants, wild mushrooms, animals and some kind of fishes. Conclusion: According to extensive studies, not only the effect of the accident but also the pathway and countermeasures against radioactive contamination have been revealed, and they are applied very effectively for restoration of environment and reconstruction of the area.