• 대한방사선방어학회:학술대회논문집
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• 2010.04a
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• pp.146-147
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• 2010

• Proceedings of the Korean Society of Medical Physics Conference
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• 1999.11a
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• pp.73-75
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• 1999

• Radiation Oncology Journal
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• v.18 no.3
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• pp.167-176
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• 2000

The objective of recent radiation therapy is to improve the quality of treatment and the after treatment quality of life. In Korea, sharing the same objective, significant advancement was made due to the gradual increase of patient number and rapid increase of treatment facilities. The advancement includes generalization of three-dimensional conformal radiotherapy (3D-CRT), application of linac-based stereotactic radiosurgery (SRS), and furthermore, the introduction of intensity modulated radiation therapy (IMRT). Authors in this paper prospectively review the followings: the advancement of radiation oncology in Korea, the recent status of four-dimensional radiation therapy, IMRT, the concept of the treatment with biological conformity, the trend of combined chemoradiotherapy, the importance of internet and radiation oncology information management system as influenced by the revolution of information technology, and finally the global trend of telemedicine in radiation oncology. Additionally, we suggest the methods to improve radiotherapy treatment, which include improvement of quality assurance (QA) measures by developing Koreanized QA protocol and system, regional study about clinical protocol development for phase three clinical trial, suggestion of unified treatment protocol and guideline by academic or research societies, domestic generation of treatment equipment's or system, establishment of nationwide data base of radiation-oncology-related information, and finally patterns-of-care study about major cancers.

• Asian Pacific Journal of Cancer Prevention
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• v.14 no.12
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• pp.7401-7407
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• 2013

Aim: To compare survival outcomes after whole brain radiation therapy (WBRT), stereotactic radiosurgery (SRS), and WBRT plus SRS combination therapy in Korea, by performing a quantitative systematic review. Materials and Methods: We searched 10 electronic databases for reports on Korean patients treated with WBRT or SRS for brain metastases published prior to July 2010. Independent reviewers screened all articles and extracted the data. When a Kaplan-Meier survival curve was available, median survival time and standard errors were calculated. Summary estimates for the outcomes in each study were calculated using the inverse variance random-effects method. Results: Among a total of 2,761 studies, 20 studies with Korean patients (n=1,053) were identified. A combination of 12 studies (n=566) with WBRT outcomes showed a median survival time of 6.0 months (95%CI: 5.9-6.2), an overall survival rate of 5.6% (95%CI: 1-24), and a 6-month survival rate of 46.5% (95%CI: 37.2-56.1). For nine studies (n=412) on SRS, the median survival was 7.9 months (95%CI: 5.1-10.8), and the 6-month survival rate was 63.1% (95%CI: 49.8-74.8). In six studies (n=75) using WBRT plus SRS, the median survival was 10.7 months (95%CI: 4.7-16.6), and the overall and 6-month survival rates were 16.8% (95%CI: 6.2-38.2) and 85.7% (95%CI: 28.3-96.9), respectively. Conclusions: WBRT plus SRS showed better 1-year survival outcome than of WBRT alone for Korean patients with metastatic brain tumors. However, the results of this analysis have to be interpreted cautiously, because the risk factors of patients were not adjusted in the included studies.

• Radiation Oncology Journal
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• v.27 no.3
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• pp.163-168
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• 2009

Purpose: This study was a retrospective evaluation of the efficacy of stereotactic radiosurgery (SRS) in patients with >4 metastases to the brain. Materials and Methods: Between January 2004 and December 2006, 68 patients with $\geq$4 multiple brain metastases were included and reviewed retrospectively. Twenty-nine patients received SRS and 39 patients received whole brain radiotherapy (WBRT). Patients with small cell lung cancers and melanomas were excluded. The primary lesions were non-small cell lung cancer (69.0%) and breast cancer (13.8%) in the SRS group and non-small cell lung cancer (64.1%), breast cancer (15.4%), colorectal cancer (12.8%), esophageal cancer (5.1%) in the WBRT group. SRS involved gamma-knife radiosurgery and delivered 10~20 Gy (median, 16 Gy) in a single fraction with a 50% marginal dose. WBRT was delivered daily in 3 Gy fractions, for a total of 30 Gy. After completion of treatment, a follow-up brain MRI or a contrast-enhanced brain CT was reviewed. The overall survival and intracranial progression-free survival were compared in each group. Results: The median follow-up period was 5 months (range, 2~19 months) in the SRS group and 6 months (range, 4~23 months) in the WBRT group. The mean number of metastatic lesions in the SRS and WBRT groups was 6 and 5, respectively. The intracranial progression-free survival and overall survival in the SRS group was 5.1 and 5.6 months, respectively, in comparison to 6.1 and 7.2 months, respectively, in the WBRT group. Conclusion: SRS was less effective than WBRT in the treatment of patients with >4 metastases to the brain.

• The Journal of Korean Society for Radiation Therapy
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• v.26 no.1
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• pp.59-67
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• 2014

Purpose : This study aims to evaluate 3D dosimetric impact for MIP image and each phase image in stereotactic body radiotherapy (SBRT) for lung cancer using volumetric modulated arc therapy (VMAT). Materials and Methods : For each of 5 patients with non-small-cell pulmonary tumors, a respiration-correlated four-dimensional computed tomography (4DCT) study was performed. We obtain ten 3D CT images corresponding to phases of a breathing cycle. Treatment plans were generated using MIP CT image and each phases 3D CT. We performed the dose verification of the TPS with use of the Ion chamber and COMPASS. The dose distribution that were 3D reconstructed using MIP CT image compared with dose distribution on the corresponding phase of the 4D CT data. Results : Gamma evaluation was performed to evaluate the accuracy of dose delivery for MIP CT data and 4D CT data of 5 patients. The average percentage of points passing the gamma criteria of 2 mm/2% about 99%. The average Homogeneity Index difference between MIP and each 3D data of patient dose was 0.03~0.04. The average difference between PTV maximum dose was 3.30 cGy, The average different Spinal Coad dose was 3.30 cGy, The average of difference with $V_{20}$, $V_{10}$, $V_5$ of Lung was -0.04%~2.32%. The average Homogeneity Index difference between MIP and each phase 3d data of all patient was -0.03~0.03. The average PTV maximum dose difference was minimum for 10% phase and maximum for 70% phase. The average Spain cord maximum dose difference was minimum for 0% phase and maximum for 50% phase. The average difference of $V_{20}$, $V_{10}$, $V_5$ of Lung show bo certain trend. Conclusion : There is no tendency of dose difference between MIP with 3D CT data of each phase. But there are appreciable difference for specific phase. It is need to study about patient group which has similar tumor location and breathing motion. Then we compare with dose distribution for each phase 3D image data or MIP image data. we will determine appropriate image data for treatment plan.

• Progress in Medical Physics
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• v.25 no.2
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• pp.110-115
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• 2014

To compare 2 beam arrangements, circumferential equally angles (EA) beams or partially angles (PA) beams for stereotactic body radiation therapy (SBRT) of primary lung cancer for intensity-modulated radiation therapy (IMRT) and volumetric-modulated arc therapy (VMAT) delivery techniques with respect to target, ipsilateral lung, contralateral lung, and organs-at-risk (OAR) dose-volume metrics, as well as treatment delivery efficiency. Data from 12 patients, four treatment plans were generated per data sets ($IMRT_{EA}$, $IMRT_{PA}$, $VMAT_{EA}$, $VMAT_{PA}$). The prescribed dose (PD) was 60 Gy in 4 fractions to 95% of the planning target volume (PTV) for a 6-MV photon beam. When compared with the IMRT and VMAT treatment plan for 2 beams, conformity index, homogeneity index, high dose spillage, D2 cm (Dmax at a distance ${\geq}2cm$ beyond the PTV), R50 (ratio of volume circumscribed by the 50% isodose line and the PTV), resulted in similar. But Dmax of the Organ at risk (OAR), spinal cord, trachea, resulted in differ between four treatment plans. Especially $HDS_{location}$ showed big difference in 21.63% vs. 26.46%.

• Radiation Oncology Journal
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• v.32 no.3
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• pp.163-169
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• 2014

Purpose: To report the results of stereotactic body radiotherapy (SBRT) for unresectable primary or recurrent cholangiocarcinoma. Materials and Methods: From January 2005 through August 2013, 58 patients with unresectable primary (n = 28) or recurrent (n = 30) cholangiocarcinoma treated by SBRT were retrospectively analyzed. The median prescribed dose was 45 Gy in 3 fractions (range, 15 to 60 Gy in 1-5 fractions). Patients were treated by SBRT only (n = 53) or EBRT + SBRT boost (n = 5). The median tumor volume was 40 mL (range, 5 to 1,287 mL). Results: The median follow-up duration was 10 months (range, 1 to 97 months). The 1-year, 2-year overall survival rates, and median survival were 45%, 20%, and 10 months, respectively. The median survival for primary group and recurrent group were 5 and 13 months, respectively. Local control rate at 1-year and 2-year were 85% and 72%, respectively. Disease progression-free survival rates at 1-year and 2-year were 26% and 23%, respectively. In univariate analysis, ECOG performance score (0-1 vs. 2-3), treatment volume (<50 vs. ${\geq}50mL$), and pre-SBRT CEA level (<5 vs. ${\geq}5ng/mL$) were significant in overall survival rate. In multivariate analysis, ECOG score (p = 0.037) and tumor volume (p = 0.030) were statistically significant. In the recurrent tumor group, patients with >12 months interval from surgery to recurrence showed statistically significant higher overall survival rate than those with ${\leq}12$ months (p = 0.026). Six patients (10%) experienced ${\geq}$grade 3 complications. Conclusion: SBRT can be considered as an effective local modality for unresectable primary or recurrent cholangiocarcinoma.

• Progress in Medical Physics
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• v.26 no.4
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• pp.223-228
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• 2015

Double-focused micro-Multileaf Collimator (${\mu}MLC$) is able to create radiation fields having sharper dose gradients at the field edges than common MLC. Therefore, ${\mu}MLC$ has been used for the stereotactic radiosurgery (SRS) and Stereotactic Radiotherapy (SRT). We evaluated the dosimetric characteristics of a doublefocused Dynamic-${\mu}MLC$ (DMLC) attached to the Elekta Synergy linear accelerator. For this study, the dosimetric parameters including, Percent Depth Dose (PDD), Leaf leakage and penumbra, have been measured by using of the radiochromic films (GafChromic EBT2), EDGE diode detector and three-dimensional water phantom. All datas were measured on 6 MV x-ray. As a result, The DMLC shows transmission below to 1% and because of double-focused construction of the DMLC, the penumbras of fields with DMLC are independent from the field sizes. In this paper, the resulting dosimetric evaluations proved the applicability of the DMLC attached to the Elekta Synergy linear accelerator.

• Radiation Oncology Journal
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• v.36 no.2
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• pp.129-138
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• 2018

Purpose: This study was conducted to compare clinical outcomes and treatment-related toxicities after stereotactic body radiation therapy (SBRT) with two different dose regimens for small hepatocellular carcinomas (HCC) ${\leq}3cm$ in size. Materials and Methods: We retrospectively reviewed 44 patients with liver-confined HCC treated between 2009 and 2014 with SBRT. Total doses of 45 Gy (n = 10) or 60 Gy (n = 34) in 3 fractions were prescribed to the 95% isodose line covering 95% of the planning target volume. Rates of local control (LC), intrahepatic failure-free survival (IHFFS), distant metastasis-free survival (DMFS), and overall survival (OS) were calculated using the Kaplan-Meier method. Results: Median follow-up was 29 months (range, 8 to 64 months). Rates at 1 and 3 years were 97.7% and 95.0% for LC, 97.7% and 80.7% for OS, 76% and 40.5% for IHFFS, and 87.3% and 79.5% for DMFS. Five patients (11.4%) experienced degradation of albumin-bilirubin grade, 2 (4.5%) degradation of Child-Pugh score, and 4 (9.1%) grade 3 or greater laboratory abnormalities within 3 months after SBRT. No significant difference was seen in any oncological outcomes or treatment-related toxicities between the two dose regimens. Conclusions: SBRT was highly effective for local control without severe toxicities in patients with HCC smaller than 3 cm. The regimen of a total dose of 45 Gy in 3 fractions was comparable to 60 Gy in efficacy and safety of SBRT for small HCC.