• Radiation Oncology Journal
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• v.36 no.1
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• pp.63-70
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• 2018

Purpose: The objective of this study was to compare dosimetric characteristics of three-dimensional conformal radiotherapy (3D-CRT) and two types of intensity-modulated radiotherapy (IMRT) which are step-and-shoot intensity modulated radiotherapy (s-IMRT) and modulated arc therapy (mARC) for thoracic esophageal cancer and analyze whether IMRT could reduce organ-at-risk (OAR) dose. Materials and Methods: We performed 3D-CRT, s-IMRT, and mARC planning for ten patients with thoracic esophageal cancer. The dose-volume histogram for each plan was extracted and the mean dose and clinically significant parameters were analyzed. Results: Analysis of target coverage showed that the conformity index (CI) and conformation number (CN) in mARC were superior to the other two plans (CI, p = 0.050; CN, p = 0.042). For the comparison of OAR, lung V5 was lowest in s-IMRT, followed by 3D-CRT, and mARC (p = 0.033). s-IMRT and mARC had lower values than 3D-CRT for heart $V_{30}$ (p = 0.039), $V_{40}$ (p = 0.040), and $V_{50}$ (p = 0.032). Conclusion: Effective conservation of the lung and heart in thoracic esophageal cancer could be expected when using s-IMRT. The mARC was lower in lung $V_{10}$, $V_{20}$, and $V_{30}$ than in 3D-CRT, but could not be proven superior in lung $V_5$. In conclusion, low-dose exposure to the lung and heart were expected to be lower in s-IMRT, reducing complications such as radiation pneumonitis or heart-related toxicities.

• Progress in Medical Physics
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• v.29 no.4
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• pp.157-163
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• 2018

Plans converted using dose-volume-histogram-based plan conversion (DPC) were evaluated by comparing them to the original plans. Changes in the dose volumetric (DV) parameters of five volumetric modulated arc therapy (VMAT) plans for head and neck (HN) cancer and five VMAT plans for prostate cancer were analyzed. For the HN plans, the homogeneity indices (HIs) of the three planning target volumes (PTV) increased by 0.03, 0.02, and 0.03, respectively, after DPC. The maximum doses to the PTVs increased by 1.20, 1.87, and 0.92 Gy, respectively, after DPC. The maximum doses to the optic chiasm, optic nerves, spinal cord, brain stem, lenses, and parotid glands increased after DPC by approximately 4.39, 3.62, 7.55, 7.96, 1.77, and 6.40 Gy, respectively. For the prostate plans after DPC, the HIs for the primary and boost PTVs increased by 0.05 and 0.03, respectively, and the maximum doses to each PTV increased by 1.84 and 0.19 Gy, respectively. After DPC, the mean doses to the rectum and femoral heads increased by approximately 6.19 and 2.79 Gy, respectively, and those to the bladder decreased by 0.20 Gy when summing the primary and boost plans. Because clinically unacceptable changes were sometimes observed after DPC, plans converted by DPC should be carefully reviewed before actual patient treatment.

• Journal of Ecology and Environment
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• v.33 no.1
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• pp.59-65
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• 2010

Because seagrass production significantly contributes to the biodiversity and production of coastal and estuarine ecosystems, accurate estimation of seagrass productivity is a critical step toward understanding the ecological roles of seagrass in these ecosystems. To develop an accurate and effective method of measuring seagrass productivity, we estimated leaf productivity of eelgrass (Zostera marina) on the southern coast of Korea using three methods, the conventional leaf marking method, the elongation-mass method (Short '87 method), and the plastochrone method. In each season, shoots were pierced through the bundle sheath using a hypodermic needle and were collected after 2-4 weeks had elapsed to estimate their productivity. The leaf elongation and the leaf plastochrone intervals varied significantly among seasons. On an annual basis, the conventional leaf marking method showed the lowest leaf productivity estimates compared to the elongation-mass method and the plastochrone method, suggesting that the conventional leaf marking method underestimated leaf productivity as it ignored leaf maturation processes and new leaf growth within the sheath. Since the elongation-mass method considered leaf maturation processes, this method produced higher leaf productivity estimates than the conventional leaf marking method. On an annual basis, the plastochrone method produced the highest leaf productivity estimates. Below-ground productivity, which can be easily estimated using the plastochrone method, ranged between 3.29 and 5.73 (mg dry weight $shoot^{-1}\;day^{-1}$) and accounted for about 17.8% to 30.3% of total productivity. Because of the high contributions of below-ground productivity to total seagrass production, we suggest that the plastochrone method is an effective and simple technique for assessing both above- and below-ground productivities.

• Korean Institute of Interior Design Journal
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• v.26 no.3
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• pp.81-90
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• 2017

Subsidiary welfare facilities in an apartment complex are one of the most important factors for consumers when they buy an apartment due to an increase of consumers' consciousness level, increase of leisure time, and increase of cultural life. This study aims to analyze layout types and characteristics of subsidiary welfare facilities at the apartment complexes in the second phase new towns, investigate the current situation and find out the improvement direction. For this purpose, this author investigated three "second phase new towns" which were designated as a new town at similar time, and selected a total of 15 apartment complexes by selecting 5 complexes in each of the three new towns. Literature survey, case visit, photo shoot, user observation survey were used as study methods. The results of the study are as follows. First, it was found that a mixed type was the most common type of plane layout types in the subsidiary welfare facilities. This type improves accessibility and equity of the residents as the facilities are appropriately placed based on the functions and the user characteristics. Second, it can be considered that a distributed type for senior citizen centers and daycare centers may give independence to specific users, but it may give a sense of alienation to the elderly. Moreover, it does not have enough community so that it is necessary to make proper supplementation. Third, there were two lay out types. The first one is that the subsidiary welfare facilities are placed with step difference and the second one is that they are placed in sunken places using the underground space. Fourth, all layout types of outdoor facilities are distributed types, and it is considered that measurements for a proper balance of accessibility and equity are required.

• Korean Journal of Soil Science and Fertilizer
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• v.30 no.4
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• pp.377-383
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• 1997

Studies were conducted on the nature of allelopathic effect of the substances in the waste of ginkgo leaves from pharmaceutic factory. In the first step, to find out whether there was any allelophatic effect, young seedlings of radish and rice were grown in the water (crude) extract of ginkgo leaf waste and in different liquid/lquid partitioned fractions of EtOAc at pH 9, EtOAc at pH 3, and BuOH. As second step, attempts were made to isolate and identify the allelophatic substance in different liquid/liquid partitioned fractions using GC/MS and NMR techniques. The water (crude) extract of ginkgo leaf waste retarded the growth of radish seedlings under 10% concentration. In case of rice seedlings, the water extract of ginkgo leaf extract showed adverse effect on the growth when combined with $3.3{\times}10^{-6}M$ gibberellin A3. All of the liquid/liquid fractions of crude extract showed strong retardation of seedling growth of radish and rice at the concentration of 1%. Allelophatic substance was isolated from the crude extract using liquid/liquid partition, column chromatography and HPLC techniques. The analytical results of isolated componet using GC/MS and NMR proved that the allelophatic substance in the ginkgo leaf wastes is catechol; one of phenol compounds. Based on the experiences current study, a practical method for the testing of allelophatic effect of crude extract of some materials was proposed. In this method, rice seeds were allowed to sprout until the length of coleoptile to reach 0.5 mm. Such seedlings were submerged in the solution containing supposedly allelophatic substance and the length of shoot and root was measured 3 days after treatment.

• Progress in Medical Physics
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• v.27 no.1
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• pp.14-24
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• 2016

Since the head and neck region is densely located with organs at risk (OAR), OAR-sparing is an important issue in the treatment of head and neck cancers. This study-in which different treatment plans were performed varying the head tilt angle on brain tumor patients-investigates the optimal head elevation angle for sparing normal organs (e.g. the hippocampus) and further compares the dosimetric characteristics of different types of radiation equipment. we performed 3D conformal radiation therapy (3D-CRT), intensity-modulated radiation therapy (IMRT), and tomotherapy on 10 patients with brain tumors in the frontal lobe while varying the head tilt angle of patients to analyze the dosimetric characteristics of different therapy methods. In each treatment plan, 95% of the tumor volume was irradiated with a dose of 40 Gy in 10 fractions. The step and shoot technique with nine beams was used for IMRT, and the same prescription dose was delivered to the tumor volume for the 3D-CRT and tomotherapy plans. The homogeneity index, conformity index, and normal tissue complication probability (NTCP) were calculated. At a head elevation angle of $30^{\circ}$, conformity of the isodose curve to the target increased on average by 53%, 8%, and 5.4%. In 3D-CRT, the maximum dose received by the brain stem decreased at $15^{\circ}$, $30^{\circ}$, and $40^{\circ}$, compared to that observed at $0^{\circ}$. The NTCP value of the hippocampus observed in each modality was the highest at a head and neck angle of $0^{\circ}$ and the lowest at $30^{\circ}$. This study demonstrates that the elevation of the patients' head tilt angle in radiation therapy improves the target region's homogeneity of dose distribution by increasing the tumor control rate and conformity of the isodose curve to the target. Moreover, the study shows that the elevation of the head tilt angle lowers the NTCP by separating the tumor volume from the normal tissues, which helps spare OARs and reduce the delivered dose to the hippocampus.

• Progress in Medical Physics
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• v.24 no.3
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• pp.154-161
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• 2013

This study assessed compared photon and proton treatment techniques, such as intensity modulated radiation therapy (IMRT), uniform scanning proton therapy (USPT), and intensity modulated proton therapy (IMPT), for a total of 10 prostate cancers. All treatment plans delivered 70 Gy to 95% of the planned target volume in 28 fractions. IMRT plans had 7 fields for the step and shoot technique, while USPT and IMPT plans employed two equally weighted, parallel-opposed lateral fields to deliver the prescribed dose to the planned target. Inverse planning was then incorporated to optimize IMPT. The homogeneity index (HI) and conformity index (CI) for the target and the normal tissue complication probability (NTCP) for organ at risk (OAR) were calculated. Although the mean HI and CI for target were not significantly different for each treatment techniques, the NTCP of the rectum was 2.233, 3.326, and 1.707 for IMRT, USPT, and IMPT, respectively. The NTCP of the bladder was 0.008, 0.003, and 0.002 respectively. The NTCP values at the rectum and bladder were significantly lower using IMPT. Our study shows that using proton therapy, particularly IMPT, to treat prostate cancer could be beneficial compared to 7-field IMRT with similar target coverage. Given these results, radiotherapy using protons, particularly optimized IMPT, is a worthwhile treatment option for prostate cancer.

• Progress in Medical Physics
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• v.21 no.4
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• pp.332-339
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• 2010

We aimed to setup an adaptive radiation therapy platform using cone-beam CT (CBCT) and multileaf collimator (MLC) log data and also intended to analyze a trend of dose calculation errors during the procedure based on a phantom study. We took CT and CBCT images of Catphan-600 (The Phantom Laboratory, USA) phantom, and made a simple step-and-shoot intensity-modulated radiation therapy (IMRT) plan based on the CT. Original plan doses were recalculated based on the CT ($CT_{plan}$) and the CBCT ($CBCT_{plan}$). Delivered monitor unit weights and leaves-positions during beam delivery for each MLC segment were extracted from the MLC log data then we reconstructed delivered doses based on the CT ($CT_{recon}$) and CBCT ($CBCT_{recon}$) respectively using the extracted information. Dose calculation errors were evaluated by two-dimensional dose discrepancies ($CT_{plan}$ was the benchmark), gamma index and dose-volume histograms (DVHs). From the dose differences and DVHs, it was estimated that the delivered dose was slightly greater than the planned dose; however, it was insignificant. Gamma index result showed that dose calculation error on CBCT using planned or reconstructed data were relatively greater than CT based calculation. In addition, there were significant discrepancies on the edge of each beam while those were less than errors due to inconsistency of CT and CBCT. $CBCT_{recon}$ showed coupled effects of above two kinds of errors; however, total error was decreased even though overall uncertainty for the evaluation of delivered dose on the CBCT was increased. Therefore, it is necessary to evaluate dose calculation errors separately as a setup error, dose calculation error due to CBCT image quality and reconstructed dose error which is actually what we want to know.

• Radiation Oncology Journal
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• v.24 no.1
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• pp.1-10
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• 2006

Puroose: To present preliminary results of intensity-modulated radiotherapy (IMRT) using the simultaneous modulated accelerated radiation therapy (SMART) boost technique in patients with nasopharyngeal carcinoma (NPC). Materials and Methods: Twenty patients who underwent IMRT for non-metastatic NPC at the Asan Medical Center between September 2001 and December 2003 were prospectively evaluated. IMRT was delivered using the 'step and shoot' SMART technique at prescribed doses of 72 Gy (2.4 Gy/day) to the gross tumor volume (GTV), 60 Gy (2 Gy/day) to the clinical target volume (CTV) and metastatic nodal station, and 46 Gy (2 Gy/day) to the clinically negative neck region. Eighteen patients also received concurrent chemotherapy using cisplatin once per week. Results: The median follow-up period was 27 months. Nineteen patients completed the treatment without interruption; the remaining patient interrupted treatment for 2 weeks owing to severe pharyngitis and malnutrition. Five patients (25%) had RTOG grade 3 mucositis, whereas nine (45%) had grade 3 pharyngitis. Seven patients (35%) lost more than 10% of their pretreatment weight, whereas 11 (55%) required intravenous fluids and/or tube feeding. There was no grade 3 or 4 chronic xerostomia. All patients showed complete response. Two patients had distant metastases and loco-regional recurrence, respectively. Conclusion: IMRT using the SMART boost technique allows parotid sparing, as shown clinically and by dosimetry, and may also be more effective biologically. A larger population of patients and a longer follow-up period are needed to evaluate ultimate tumor control and late toxicity.

• Proceedings of the Korean Society of Medical Physics Conference
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• 2003.09a
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• pp.37-37
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• 2003

목적 : 일반적으로 세기조절방사선치료 조사면의 작은 조각 크기에 대해, 이상적인 플루언스 지도 혹은 치료계획장치로부터의 최적화된 결과에 가까운 선량분포에서 더 좋은 leaf sequence를 얻을 수 있다. 한편, 치료중 장기의 움직임이 가장 작은 조각 크기의 선택을 방해하는 문제는 항상 존재한다. 게다가, 전통적인 정지 조사면과 달리 표적이 움직이는 동안 조사면 자체도 움직이므로 움직이는 표적에 대한 세기조절방사선치료의 경우에서 적절한 표적 마진에 관한 질문이 제기되어왔다. 따라서, 이 연구에서는 조각 크기에 대한 치료중 표적 움직임의 효과를 연구하였다. 대상 및 방법 : 세기조절방사선치료 플루언스 지도에 대해, 다양한 크기 - 0.5$\times$0.5, 1.0$\times$1.0, $1.5\times$1.5, 2.0$\times$2.0, 3.0$\times$3.0, 4.0$\times$4.0, 5.0$\times$5.0 $ extrm{cm}^2$ - 의 정사각형 패턴들을 설계하였고, Leaf sequence 는 step-and-shoot 빔 전달 방법을 이용하였다. 인접 조각들 사이의 세기 비율은 0.2, 0.4, 0.6, 0.8, 1.0로 하였고, 표적 움직임은 범위가 0.5-2.0 cm인 사인곡선 형태로 가정하였다. 움직임 묘사를 위해 동적 leaf 의 움직임이 표적의 움직임 을 반영하도록 계산되었고 움직임의 효과를 분석하기 위해 필름선량측정을 수행하였다. 결과 : 인접 조각의 세기 비율은 모든 경우에서 저하되었고, 호흡 진폭의 반보다 작은 조각 크기에 대한 선량분포는 임상적으로 유의할만큼 저하된 세기 지도를 보였다. 조각에 대해 방사선 조사시간의 두 호흡주기이상에 대해서는, 표적 마진 주위의 선량분포가 통상적인 정지 조사면에서와 같았다. 결론 : 플루언스 지도에서 세기조절방사선치료 조각의 최소 크기는 치료중 장기 움직임을 고려한 후 선택되어야 한다. 조각에 대한 방사선 조사시간의 두 호흡주기이상에 대해서는, 표적 마진을 기존의 정지 조사면과 같게 정의할 수 있었다.