• The Magazine of the Society of Air-Conditioning and Refrigerating Engineers of Korea
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• v.16 no.4
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• pp.375-382
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• 1987

Accurate solar radiation data are fundamental to the design of HVAC systems and solar driven devices. Unfortunately, the total radiation data on a horizontal surface has been only reported by meteorological office. Consequently, there is interest in development of model to estimate the solar radiation data. Based on the statistically estimated TAC data which were obtained from measured hourly values collected over a period of ten years at Seoul, the solar radiation model was determined. Atmospheric transmittance for this model was presented in the form of polynominal.

• Progress in Medical Physics
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• v.28 no.4
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• pp.218-225
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• 2017

Effects on skin caused by the dose from linear accelerator (LINAC) opposing portal irradiation and TomoDirect 3-D modeling treatment according to the radiation devices and treatment methods were measured, and a comparative analysis was performed. Two groups of 10 patients each were created and measurements were carried out using an optically stimulated luminescence dosimeter. These patients were already receiving radiation treatment in the hospital. Using the SPSS statistical program, the minimum and maximum average standard deviations of the measured skin dose data were obtained. Two types of treatment method were selected as independent variables; the measured points and total average were the dependent variables. An independent sample T-test was used, and it was checked whether there was a significance probability between the two groups. The average of the measured results for the LINAC opposing portal radiation was 117.7 cGy and PDD 65.39% for the inner breast, 144.7 cGy and PDD 80.39% for the outer breast, 143.2 cGy and PDD 79.56% for the upper breast, 151.4 cGy and PDD 84.11% for the lower breast, 149.6 cGy and PDD 83.11% for the axilla, and 141.32 cGy and PDD 78.51% for the total average. In contrast, for TomoDirect 3-D conformal radiotherapy, the corresponding measurement values were 137.6 cGy and PDD 76.44%, 152.3 cGy and PDD 84.61%, 148.6 cGy and PDD 82.56%, 159.7 cGy and PDD 88.72%, and 148.6 cGy PDD 82.56%, respectively, and the total average was 149.36 cGy and PDD 82.98%. To determine if the difference between the total averages was statistically significant, the independent sample T-test of the SPSS statistical program was used, which indicated that the P-value was P=0.024, which was 0.05 lower than the significance level. Thus, it can be understood that the null hypothesis can be dismissed, and that there was a difference in the averages. In conclusion, even though the treatment dose was similar, there could be a difference in the dose entering the body surface from the radiation treatment plan; however, depending on the properties of the treatment devices, there is a difference in the dose affecting the body surface. Thus, the absorbed dose entering the body surface can be high. During breast cancer radiotherapy, radiation dermatitis occurs in almost all patients. Most patients have a difficult time while undergoing treatment, and therefore, when choosing a radiotherapy treatment method, minimizing radiation dermatitis is an important consideration.

• Radiation Oncology Journal
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• v.36 no.1
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• pp.35-44
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• 2018

Purpose: To evaluate clinical outcomes according to radiation dose in patients with limited-stage small-cell lung cancer (LS-SCLC) treated with concurrent chemoradiotherapy (CCRT). Materials and Methods: From January 2006 to December 2015, 38 patients with LS-SCLC were treated with CCRT with etoposide and cisplatin. Total radiation doses ranged from 45 Gy to 66 Gy (1.8-2 Gy/fraction) and were classified into three groups: 45-54 Gy, 60-63 Gy, and 66 Gy. The impact of radiation dose on survival outcomes were evaluated. Toxicities were evaluated according to the Common Terminology Criteria for Adverse Events version 4.03. Results: The median follow-up period was 21 months. The 2-year overall survival (OS) and local failure-free survival (LFFS) rates were 45.8% and 67.5%, respectively. The 2-year LFFS rates were 33.3% for 45-54 Gy group, 68.6% for 60-63 Gy group, and 87.1% for 66 Gy group (p = 0.014). In multivariate analysis, radiation dose was a significant factor for LFFS (p = 0.015). Although radiation dose was not a significant factor for OS and disease-free survival (DFS) in multivariate analysis, both OS and DFS of 66 Gy group tended to be better than that of 45-63 Gy group in univariate analysis. However, there were no differences in severe toxicities among three groups. Conclusion: Higher radiation dose achieved better local control in patients with LS-SCLC treated with CCRT. In addition, a total dose of 66 Gy tended to improve OS and DFS.

• Asian Pacific Journal of Cancer Prevention
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• v.14 no.10
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• pp.5725-5730
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• 2013

Cancer patients often suffer from local tumor recurrence after radiation therapy. Cell cycling, an intricate sequence of events which guarantees high genomic fidelity, has been suggested to affect DNA damage responses and eventual radioresistant characteristics of cancer cells. Here, we established a radioresistant lung cancer cell line, A549R, by exposing the parental A549 cells to repeated ${\gamma}$-ray irradiation with a total dose of 60 Gy. The radiosensitivity of A549 and A549R was confirmed using colony formation assays. We then focused on examination of the cell cycle distribution between A549 and A549R and found that the proportion of cells in the radioresistant S phase increased, whereas that in the radiosensitive G1 phase decreased. When A549 and A549R cells were exposed to 4 Gy irradiation the total differences in cell cycle redistribution suggested that G2-M cell cycle arrest plays a predominant role in mediating radioresistance. In order to further explore the possible mechanisms behind the cell cycle related radioresistance, we examined the expression of Cdc25 proteins which orchestrate cell cycle transitions. The results showed that expression of Cdc25c increased accompanied by the decrease of Cdc25a and we proposed that the quantity of Cdc25c, rather than activated Cdc25c or Cdc25a, determines the radioresistance of cells.

• Radiation Oncology Journal
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• v.35 no.1
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• pp.25-31
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• 2017

Purpose: The purpose of this study was to describe treatment patterns of radiotherapy (RT) for prostate cancer in Korea. Materials and Methods: A questionnaire about radiation treatment technique and principles in 2013 was sent to 83 radiation oncologists and data from 57 hospitals were collected analyzed to find patterns of RT for prostate cancer patients in Korea. Results: The number of patients with prostate cancer treated with definitive RT ranged from 1 to 72 per hospital in 2013. RT doses and target volumes increased according to risk groups but the range of radiation doses was wide (60 to 81.4 Gy) and the fraction size was diverse (1.8 to 5 Gy). Intensity-modulated radiation therapy was used for definitive treatment in 93.8% of hospitals. Hormonal therapy was integrated with radiation for intermediate (63.2%) and high risk patients (77.2%). Adjuvant RT after radical prostatectomy was performed in 46 hospitals (80.7%). Indications of adjuvant RT included positive resection margin, seminal vesicle invasion, and capsular invasion. The total dose for adjuvant RT ranged from 50 to 72 Gy in 24-39 fractions. Salvage RT was delivered with findings of consecutive elevations in prostate-specific antigen (PSA), PSA level over 0.2 ng/mL, or clinical recurrence. The total radiation doses ranged from 50 to 80 Gy with a range of 1.8 to 2.5 Gy per fraction for salvage RT. Conclusion: This nationwide patterns of care study suggests that variable radiation techniques and a diverse range of dose fractionation schemes are applied for prostate cancer treatment in Korea. Standard guidelines for RT in prostate cancer need to be developed.

• Rapid Communication in Photoscience
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• v.3 no.1
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• pp.25-27
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• 2014

The relative importance of radiation dose, storage time, and temperature in radiation processing of spinach (Spinacia oleracea L.), was evaluated in terms of the postharvest quality through a model study using leaf disks. Physiological activity and chlorophyll and carotenoid contents were measured to represent the postharvest quality (in terms of external appearance) of spinach, a leafy green vegetable. At $22^{\circ}C$ and $30^{\circ}C$, the higher gamma-radiation dose caused a greater decrease in the physiological activity, depending on the storage time of 4 d. However, this decrease was not significant at $4^{\circ}C$ and $15^{\circ}C$. Total chlorophyll and carotenoid contents were substantially decreased by 3 kGy at $15^{\circ}C$, and dose-dependently by 0.5-3 kGy at $22^{\circ}C$. In contrast, the proportion of lutein in total carotenoid was significantly increased in the 2-3-kGy samples only at $22^{\circ}C$, while that of ${\beta}$-carotene was slightly decreased, indicating progression of leaf aging. These data suggest that the unfavorable effect of gamma irradiation on the postharvest quality of spinach could be avoided or controlled by the storage time or temperature rather than the radiation dose. The current study could be available to improve radiation processing of other leafy green vegetables.

• Journal of Radiation Protection and Research
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• v.28 no.2
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• pp.127-135
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• 2003

The primary contributors to the total occupational radiation exposure in operating nuclear power plants are operation and maintenance activities doting refueling outages. The Advanced Power Reactor 1400 (APR1400) includes a number of design improvements and plans to utilize advanced maintenance methods and robotics to minimize the annual collective dose. The major radiation exposure reduction features implemented in APR1400 are a permanent refueling pool seal, quick opening transfer tube blind flange, improved hydrogen peroxide injection at shutdown, improved permanent steam generator work platforms, and more effective temporary shielding. The estimated average annual occupational radiation exposure for APR1400 based on the reference plant experience and an engineering judgment is determined to be in the order of 0.4 man-Sv, which is well within the design goal of 1 man-Sv. The basis of this average annual occupational radiation exposure estimation is an eighteen (18) month fuel cycle with maintenance performed to steam generators and reactor coolant pumps during refueling outage. The outage duration is assumed to be 28 days. The outage work is to be performed on a 24 hour per day basis, seven (7) days a week with overlapping twelve (12) hour work shifts. The occupational radiation exposure for APR1400 is also determined by an alternate method which consists of estimating radiation exposures expected for the major activities during the refueling outage. The major outage activities that cause the majority of the total radiation exposure during refueling outage such as fuel handling, reactor coolant pump maintenance, steam generator inspection and maintenance, reactor vessel head area maintenance, decontamination, and ICI & instrumentation maintenance activities are evaluated at a task level. The calculated value using this method is in close agreement with the value of 0.4 man-Sv, that has been determined based on the experience aid engineering judgement. Therefore, with the As Low As Reasonably Achievable (ALARA) advanced design features incorporated in the design, APR1400 design is to meet its design goal with sufficient margin, that is, more than a factor of two (2), if operated on art eighteen (18) month fuel cycle.

• Journal of Ginseng Research
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• v.22 no.1
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• pp.1-10
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• 1998

In the present study, to determine whether the antioxidative components of Korean red ginseng protect against radiation damage and the possible relationship among the radioprotective effects and antioxidant actions, the effects of total saponin (200 mg/kg, ip) and lipophilic fraction (200 mg/kg, oral) preferment of mice on the survival ratio, major antioxidant enzymes (SOD, catalase and glutathione peroxidase) activities, glutathione levels and lipid peroxidation in the liver were exiled for 2 weeks after whole ${\gamma}$-body ${\gamma}$-irradiation (6.5 Gy). The 30-day survival ratio increased from 10% to 57% and 40% for mice treated with total saponin and lipophilic fraction, respectively. On day 14 after ${\gamma}$-irradiation, the ginseng total saponin pretreatment produced a slight increase of antioxidant enzymes activities and significantly Increased reduced glutathione (GSH) contents (p<0.05) in the liver compared with non-treated group. Pretreatment with ginseng total saponin significantly deceased GSSG/total GSH ratio (p<0.05) without change of GSSG in the liver and inhibited the radiation-induced incense in the hepatic malondialdehyde levels. (p<0.05) In these results, GSH plays an important role in the liver in several detoxifications and the reduction of lipid peroxides. Thus, it appears that total saponin of red ginseng exerts its radioprotective effect by accelerating the production of endogenous antioxidants, such as glutathione from radiation induced damages and thereby oxygen free radicals.

• Radiation Oncology Journal
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• v.34 no.4
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• pp.313-321
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• 2016

Purpose: Total scalp irradiation (TSI) is a rare but challenging indication. We previously reported that non-coplanar intensity-modulated radiotherapy (IMRT) was superior to coplanar IMRT in organ-at-risk (OAR) protection and target dose distribution. This consecutive treatment planning study compared IMRT with volumetric-modulated arc therapy (VMAT). Materials and Methods: A retrospective treatment plan databank search was performed and 5 patient cases were randomly selected. Cranial imaging was restored from the initial planning computed tomography (CT) and target volumes and OAR were redelineated. For each patients, three treatment plans were calculated (coplanar/non-coplanar IMRT, VMAT; prescribed dose 50 Gy, single dose 2 Gy). Conformity, homogeneity and dose volume histograms were used for plan. Results: VMAT featured the lowest monitor units and the sharpest dose gradient (1.6 Gy/mm). Planning target volume (PTV) coverage and homogeneity was better in VMAT (coverage, 0.95; homogeneity index [HI], 0.118) compared to IMRT (coverage, 0.94; HI, 0.119) but coplanar IMRT produced the most conformal plans (conformity index [CI], 0.43). Minimum PTV dose range was 66.8%-88.4% in coplanar, 77.5%-88.2% in non-coplanar IMRT and 82.8%-90.3% in VMAT. Mean dose to the brain, brain stem, optic system (maximum dose) and lenses were 18.6, 13.2, 9.1, and 5.2 Gy for VMAT, 21.9, 13.4, 14.5, and 6.3 Gy for non-coplanar and 22.8, 16.5, 11.5, and 5.9 Gy for coplanar IMRT. Maximum optic chiasm dose was 7.7, 8.4, and 11.1 Gy (non-coplanar IMRT, VMAT, and coplanar IMRT). Conclusion: Target coverage, homogeneity and OAR protection, was slightly superior in VMAT plans which also produced the sharpest dose gradient towards healthy tissue.

• Radiation Oncology Journal
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• v.12 no.2
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• pp.159-164
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• 1994

Purpose : To evaluate the role of postoperative radiotherapy in the management of primary or recurrent intracranial meningiomas. Methods and Materials : A retrospective review of 34 intracranial meningioma patients referred to the Yonsei Cancer Center for postoperative radiotherapy between 1981 and 1990 was undertaken. Of the 34 patients, 24 patients received elective postoperative radiotherapy after total or subtotal resection(Group 1), and 10 patients received postoperative radiotherapy as a salvage treatment for recurrent tumors(Group 2). Ten patients received postoperative radiotherapy after total resection, and twenty-four after subtotal resection. Ten patients who had total tumor resection were referred for radiotherapy either because of angioblastic or malignant histologic type(4 patients in Group 1) or because of recurrent disease after initial surgery(6 patients in Group 2). Radiation dose of 50-56 Gy was delivered over a period of 5-5.5 weeks using 4MV LINAC or Co-60 teletherapy unit. Results : Overall actuarial progression free survival(PFS) at 5 years was $80\%$. Survival was most likely affected by histologic subtypes. Five year PFS rate was $52\%$ for benign angioblastic histology as compared with $100\%$ for classic benign histology. For malignant meningiomas, 5 year PFS rate was $44\%$. The recurrence rates of classic, angioblastic, and malignant type were $5\%(1/21),\;80\%(4/5)$, and $50\%(4/8)$, respectively. The duration between salvage post-operative radiotherapy and recurrence was longer than the duration between initial surgery and recurrence in the patients of group 2 with angioblastic or malignant histology. Conclusion . Postoperative radiotherapy of primary or recurrent intracranial meningiomas appears to be effective modality, especially in the patients with classic meningiomas. In angioblastic or malignant histologies, a more effective approach seems to be needed for decreasing recurrence rate.