• Korean Journal of Agricultural Science
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• v.22 no.2
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• pp.156-162
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• 1995

This study was carried out to select the useful mutants among 20 lines treated with mutagen, gamma ray. These materials were treated with 15, 20, 25 and 30Krads, respectively and sowed at experimental field of College of Agriculture on 27th May, 1995. Items surveyed were germination rate and loss of chlorophyll at seedling stages, abnormal reproductive organs, discordance of flowering times and stem and ear height at ripening stages. The germination rate of lines treated with 15 Krad was different. The germination rate of the IK1, IK2 and Sinki lines were high, while the IK3, A632 and FR140 lines were very low. At same dose level, the germination rate of both IK1/H26 and Puyo synthetic variety were different; the germination rate of the IK1/H26 was high as above 70% at all treatments, while that of the Puyo synthetic variety was very poor at above 20 Krad. Generally stem adn ear height of the IK1/H26 were gradually decreased as the dose of mutagen increased, but there was no difference in stem and ear height of the IK1/H26 when this line was treated with 20Krad. The stem and ear height of lines treated with 15 Krad were shown to be decreased than those of check with non-treatment. The number of tiller of tillering lines were not greatly affected by ${\gamma}$-ray treatment.

• Radiation Oncology Journal
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• v.11 no.1
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• pp.69-77
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• 1993

Treatment of cerebellar medulloblastoma has been much improved with modern surgical technique for gross total tumor removal and adequate radiation therapy for the whole craniospinal axis. Questions have been arosen about the optimal radiation dose for the preventive treatment of whole cranium and whole spinal axis. Recently, many authors have reported their treatment results as comparable to older data, using lower than conventional dose of 3,600 cGy-4,000 cGy. For 50 patients treated between 1981 and 1990 at the Department of Radiation Therapy of SNUH, retrospective analysis was done for the treatment result, especially the neuraxis control, by radiation dose for the presymptomatic area of the disease. Analysis only by total spinal dose did not give any significant difference. But further analysis by following patient group; 3,600 cGy/150 cGy (n=6), 3,000 cGy/150 cGy (n=10), 2,400 cGy/150 cGy (n=17) and 2,400 cGy/100-120 cGy (n=11) showed significant improvement of neuraxis control by decreasing order (p =0.003). There was no significant difference in overall survival between the groups. For the 19 patients who had been confirmed initially as having no neuraxis disease, TDF 30 was the cur-off value that could prevent neuraxis failure (p =0.004). We couldn't define any TDF value that give reasonable control for the patient group with positive CSF study at initial diagnosis.

• Progress in Medical Physics
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• v.8 no.2
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• pp.45-57
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• 1997

It is mandatory to measure accurately the dose distribution and the total absorbed dose of fast neutron for putting it to the clinical use. At present the methods of measurement of fast neutron are proposed largely by American Associations of Physicists in Medicine, European Clinical Neutron Dosimetry Group, and International Commission on Radiation Units and Measurements. The complexity of measurement, however, induces the methodological differences between them. In our study, therefore, we tried to establish a unique technique of measurement by means of measuring the emitted doses and the dose distribution of fast neutron beam from neutron therapy machine, and to invent a standard method of measurement adequate to our situation. For measuring the absorbed doses and the dose distribution of fast neutron beam, we used IC-17 and IC-18 ion chambers manufactured by A-150 plastic(tissue-equivalent material), IC-17M ion chamber manufactured by magnesium, TE gas and Ar gas, and RDM 2A electrometer. The magnitude of gamma-contamination intermingled with fast neutron beam was about 13％ at 5cm depth of standard irradiated field, and increased as the depth was increased. At the central axis the maximum dose depth and 50％ dose depth were 1.32cm and 14.8cm, respectively. The surface dose rate was 41.6-54.1％ throughout the entire irradiated fields and increased as the irradiated fields were increased. Beam profile was that the horn effect of about 7.5％ appeared at 2.5cm depth and the flattest at 10cm depth.

• Radiation Oncology Journal
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• v.14 no.1
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• pp.33-39
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• 1996

Purpose : This study was done to analyze survivals, patterns of failure, and complications of early uterine cervix cancer after curative radiotherapy. Materials and Methods : Eighty patients with uterine cervix cancer FIGO Stage IB (48 cases) and Stage IIA (32 cases) treated with radiotherapy were analyzed retrospectively. Patients were treated from November 1985 to May 1993, and minimum follow up period was 24 months and 6 cases were lost to follow up. All of them were treated with external radiotherapy and different fractions of high dose rate intracavitary radiotherapy, Survival rates, failure patterns, complication rates and degrees of severity were analyzed according to several factors. Results : Overall 5 year survival rate and relapse free survival rate were $72.3\%$, and $72.8\%$ respectively. Prognostic factors were stage, size, pathology, RT response and there was no significant survival difference among the reasons of radiotherapy choice. There were 19 cases of treatment failure, another 3 cases were not tumor related death, and most of treatment related failure occurred within 24 months Late complication rate of bladder and rectum were $8.8\%,\;15\%$ respectively, frequency and severity of complication were correlated with ICR fractionation dose and total dose. Conclusion : These results showed that survival rates of early stage radiation treated cervix cancer patients were comparable to surgical series, but more aggressive treatment methods needed for stage IIA poor prognostic patients. To decrease late complication, choice of proper ICR dose and meticulous vaginal packing is needed.

• Polymer(Korea)
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• v.26 no.6
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• pp.792-802
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• 2002

In this study, hydrogels from mixtures of poly (vinyl alcohol) (PVA)/poly(N-vinylpyrrolidone) (PVP)/glycerin/chitosan were prepared by γ-ray irradiation and the mechanical properties such as gelation, water absorptivity, and gel strength were examined to evaluate the applicability of these for wound dressing. Then PVA:PVP was weight ratio of 6 : 4, the concentration of chitosan was 0.3 wt%, the concentration of glycerin was in the range of 0∼5 wt%t. The solid concentration of PVA/PVP/glycerin/chitosan solution was 15 wt%. Gamma irradiation doses of 25, 35, 50, and 60 kGy were exposed to a mixture of PVA/PVP/glycerin/chitosan to evaluate the effect of irradiation dose. Gel content and gel strength increased as glycerin concentration in PVA/PVP/glycerin/chitosan decreased, and as irradiation dose increased. Swelling degree increased as glycerin concentration in PVA/PVP/glycerin/chitosan increased, and as irradiation dose decreased. The glycerin in PVA/PVP/glycerini/chitosan hydrogel prevented the transformation of shape. These hydrogel dressings had better curing effect than vaseline gauge.

• Journal of Life Science
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• v.23 no.12
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• pp.1415-1419
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• 2013

Electron beam (EB) irradiation was tested to determine the dose required to eradicate plant pathogens, such as Botrytis cinerea and Agrobacterium rhizogenes, from the infected seeds without affecting the germination rate of the irradiated vegetable seeds, including crown daisy, cucumber, hot pepper, green onion, leaf lettuce, and radish seeds. EB irradiation of 1.5 kGy and 2 kGy was sufficient to kill 100% of hairy root disease bacteria and gray mold conidia, respectively. EB irradiation showed no effect or minimal effect on the germination rate of the crown daisy, cucumber, green onion, and radish seeds. However, the germination rate of the hot pepper and leaf lettuce seeds was significantly reduced by using 2 kGy of EB irradiation. Difference in susceptibility to EB irradiation appears not to be related to the weight of each seed, but to the intrinsic characteristic of each plant. Conclusively, EB irradiation might be a useful way to decontaminate crown daisy, cucumber, green onion, and radish seeds.

• Proceedings of the Korean Society of Medical Physics Conference
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• 2004.11a
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• pp.59-63
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• 2004

IAEA's Guidance Levels have been provided for Western people to the end. Guidance levels lower than the IAEA'S will be necessary in view of korean people's proportions. Therefore, We need to develope the standard doses for korean people. And we conducted a nationwide survey of patient dose from x-ray examinations in korea. 278 institutions were selected from Members Book of Korean Hospital Association. The valid response rate was approximately 57.9%. Doses were calculated from the questionnaires by NDD method. The results were as follows; 1) General radiographic equipments were 43%, fluoroscopic equipments 29%, dental equipments 13%, CT units 8% and mamographic units 7%. 2) According to classification by rectification way, three-phase equipments were 30%, inverter-type generators 29%, single- phase equipments 26%, unknown units 6%. 3) According to classification by receptor system, film-screen types were 46%, CR types 27%, OR types18% and unknown types 9%. 4) The number of examinations were chest 48%, spine 17% and abdomen 13%. 5) Patient doses were head AP 3.1 mGy, abdomen AP 3.5 mGy and chest PA 0.4 mGy.

• Radiation Oncology Journal
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• v.9 no.2
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• pp.343-350
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• 1991

The quasi-conformation therapy was performed to get a homogeneous dose distributions for irregeular shaped tumor lesion by using the arc moving beam and beam modifying filter which was made by cerrobend alloy($\rho$=9.4 g/cc) metal. In our dose calcuation programme, it was fundmentally based on Clarkson's method to calcuate the irregular multi-step block field in rotation therapy. In this study, the expected relative depth doses under multipartial attenuator agree well with measured data at same plane. The results of comparison the dose computation with that of TLD measurement are very closed within ${\pm}5\%$ uncertainties in the irradiation to phantom with quasi-comformation method. And it has shown that irregular typed multi-step filter can be applied to quasi-conformation therapy in high energy radiation plannings.

• Korean Journal of Environmental Agriculture
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• v.20 no.2
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• pp.116-121
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• 2001

To observe the stimulating effects of low dose ${\gamma}$ - radiation on the dormancy breaking and physiological activity, potato (Solanum tuberosum L. cv. Dejima) were irradiated at the dose of $0.5{\sim}30$ Gy. Low dose ${\gamma}$ - radiation exhibited promoting effects on the sprouting rate within the range of optimum dose of 1 Gy and 2 Gy and on the sprout length within the range of optimum dose of 2 Gy and 4 Gy. Regardless of storage duration and irradiation doses, the number of sprouts was enhanced. The number of sprouts, which were reserved for 15 days after production (DAP), were significantly increased under 4, 8 and 16 Gy irradiation. The growth of 45 DAP sprouts was extremely stimulated under 4 Gy irradiation accompanying the increase of peroxidase activity in the plantlet. In this study, it was also suggested that the activities of antioxidative enzymes of potato plantlets were not related to the irradiation dose during the plantlet development with the exception of decrease in catalase activity.

• Journal of Radiation Protection and Research
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• v.11 no.1
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• pp.3-14
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• 1986

A stud has been carried out for figuring out real photon spectrum from an observed gamma-ray spectrum by means of response matrix method, which is known one of the relatively convenient method for the estimation of exposure rate of a complex gamma ray field in comparison with graphical analysis and least square fitting of the measured spectrum. A 3'${\times}$3' cylindrical Nal(T1) scintillation detector in association with multichannel pulse height analyzer and six reference gamma ray sources covering the photon energy range of 0.05 to 2.0 MeV were used. In dividing the energy region for the construction of response matrix, two different approaches were attempted. One is dividing the entire energy region of interest into 20 bins, one of which corresponds to a width of 0.1 MeV to form $20{\times}20$ matrix, and another is dividing the 2 MeV region into 14 bins to form $14{\times}14$ matrix consists of $0.1(MeV)^{1/2}$ intervals assuming the resolution of the detector is dependent on square root of the incident photon energy. Inversion of thus constructed matrices was performed by a computor(P-E8/32) using the program attached to the end of this paper. The resultant exposure rates obtained by this method were in good agreement, within 10% with those calculated by ordinary formula widely used for a gamma-ray field of known energy and flux. It is concluded that the photen flux obtained by the response matrix constructed under the assumption of $E^{1/2}$ dependence is more realistic than that obtained by the matrix consist of identical energy bins in dosimetrical point of view.