성문암 세기조절 방사선치료에서 변형영상정합을 이용한 선량변화 평가

김우철,민철기,이석,최상현,조광환,정재홍,김은석,여승구,권수일,이길동,Kim, Woo Chul,Min, Chul Kee,Lee, Suk,Choi, Sang Hyoun,Cho, Kwang Hwan,Jung, Jae Hong,Kim, Eun Seog,Yeo, Seung-Gu,Kwon, Soo-Il,Lee, Kil-Dong 한국의학물리학회 2014 의학물리 Vol.25 No.3

본 연구는 IMRT가 적용된 성문암 환자에 대하여 CBCT영상과 변형영상 정합기법을 이용하여 치료기간 동안 실제 환자에게 전달되는 선량 변화를 평가하고자 하였다. B-spline 알고리즘을 사용한 변형영상정합 시스템을 통해 치료 중 1주 간격으로 얻은 CBCT를 재구성하고 치료계획을 재계산하여 종양과 결정장기의 선량 분포를 비교하였다. 체중에 따른 체적변화는 3~5 주부터 평균 1.38~2.04 kg로 증가하였으며 체표면의 변화는 평균 2.1 mm로 감소하였다. 또한, 3주 이후의 경동맥에 전달된 선량은 계획되었던 값보다 최대 8.76%로 증가하였고, 갑상선샘은 26.4%로 감소하였다. 종양의 물리적의 평가인자인 PITV, TCI, rDHI, mDHI 그리고, CN은 치료 계획된 값보다 각각 평균 4.32%, 5.78%, 44.54%, 12.32% 그리고, 7.11%로 감소하였다. PTV에 대한 $D_{max}$는 평균 2.99% 증가하였고, $D_{mean}$, $V_{67.50}$, $D_{95}$는 각각 평균 1.52%, 5.78%, 11.94%로 감소하였다. 체중변화에 따른 체적의 변화가 없더라도 체형변화는 발생하였고, 좁은 여유마진을 가지는 IMRT는 이러한 변화에 민감하게 반응하였다. 성문암에 대한 IMRT 적용 시 환자의 체중변화를 관찰과 함께 변화를 기록하고 치료 중 변형영상정합 시스템을 이용하여 선량분포를 평가할 필요가 있다. 최종적으로 치료 중 실제 전달되는 선량평가는 적응형치료계획을 통하여 확인하고 정확한 선량전달이 필요하다고 사료된다. The purpose of this study is to evaluate the variation of the dose which is delivered to the patients with glottis cancer under IMRT (intensity modulated radiation therapy) by using the 3D registration with CBCT (cone beam CT) images and the DIR (deformable image registration) techniques. The CBCT images which were obtained at a one-week interval were reconstructed by using B-spline algorithm in DIR system, and doses were recalculated based on the newly obtained CBCT images. The dose distributions to the tumor and the critical organs were compared with reference. For the change of volume depending on weight at 3 to 5 weeks, there was increased of 1.38~2.04 kg on average. For the body surface depending on weight, there was decreased of 2.1 mm. The dose with transmitted to the carotid since three weeks was increased compared be more than 8.76% planned, and the thyroid gland was decreased to 26.4%. For the physical evaluation factors of the tumor, PITV, TCI, rDHI, mDHI, and CN were decreased to 4.32%, 5.78%, 44.54%, 12.32%, and 7.11%, respectively. Moreover, $D_{max}$, $D_{mean}$, $V_{67.50}$, and $D_{95}$ for PTV were increased or decreased to 2.99%, 1.52%, 5.78%, and 11.94%, respectively. Although there was no change of volume depending on weight, the change of body types occurred, and IMRT with the narrow composure margin sensitively responded to such a changing. For the glottis IMRT, the patient's weight changes should be observed and recorded to evaluate the actual dose distribution by using the DIR techniques, and more the adaptive treatment planning during the treatment course is needed to deliver the accurate dose to the patients.

골반강 내 방사선 치료 환자에서 Electronic Portal Imaging Device(EPID)를 이용한 Portal Image의 유용성에 관한 연구

김우철,박원,김현정,박성용,조영갑,노준규,서창옥,김귀언,Kim Woo Chul,Park Won,Kim Heon Jong,Park Seong Young,Cho Young Kap,Loh John J,Suh Chang Ok,Kim Gwi Eon 대한방사선종양학회 1998 Radiation Oncology Journal Vol.16 No.4

Purpose : To evaluate the usefulness of electronic portal imaging device through objective compare of the images acquired using an EPID and a conventional port film Materials and Methods : From Apr. to Oct. 1997, a total of 150 sets of images from 20 patients who received radiation therapy in the pelvis area were evaluated in the Inha University Hospital and Severance Hospital. A dual image recording technique was devised to obtain both electronic portal images and port film images simultaneously with one treatment course. We did not perform double exposure five to ten images were acquired from each patient. All images were acquired from posteroanterior (PA) view except images from two patients. A dose rate of 100-300 Mu/min and a 10-MV X-ray beam were used and 2-10 MUs were required to produce a verification image during treatment. Kodak diagnostic film with metal/film imaging cassette which was located on the top of the EPID detector was used for the port film. The source to detector distance was 140 cm. Eight anatomical landmarks (pelvic brim, sacrum, acetabulum. iliopectineal line, symphysis, ischium, obturator foramen, sacroiliac joint) were assessed. Four radiation oncologist joined to evaluate each image. The individual landmarks in the port film or in the EPID were rated - very clear (1), clear (2), visible (3), not clear (4), not visible (5). Results : Using an video camera based EPID system. there was no difference of image quality between no enhanced EPID images and port film images. However, when we provided some change with window level for the portal image, the visibility of the sacrum and obturator foramen was improved in the portal images than in the port film images. All anatomical landmarks were more visible in the portal images than in the port film when we applied the CLAHE mode enhancement. The images acquired using an matrix ion chamber type EPID were also improved image qualify after window level adjustment. Conclusion : The quality of image acquired using an electronic portal imaging device was comparable to that of the port film. When we used the enhance mode or window level adjustment. the image quality of the EPID was superior to that of the port film. EPID may replace the port film. 목적 : matrix ion chamber type의 EPID와 video camera based EPID를 이용한 portal image와 기존의 film을 이용한 port film의 영상의 질을 객관적으로 비교 평가하여 EPID의 유용성을 알아보고자 본 연구를 계획하였다. 대상 및 방법 : 1997년 4월부터 10월까지의 인하대 병원과 세브란스 병원에서 방사선 치료를 받은 골반강내 치료 환자 각 10명씩을 대상으로 환자 1명 당 5-10회의 port film과 EPID를 이용한 portal image를 동시에 얻어 비교하였다. 환자의 나이는 32세에서 79세이었고 2명의 AP영상을 제외하고는 모두 PA영상을 얻었다. 환자의 두께는 17cm에서 20cm으로 비교적 균일하였다. beam energy는 10MV X-ray를 사용하였고 dose rate은 100-300MU/min으로 2-10MU을 주어 영상을 얻었다. port film은 Kodak diagnostic film을 사용하였고 film을 넣는 cassette는 납을 전후에 부착한 것을 이용하였다. source to detector(film) distance는 140cm으로 하였다. 영상의 판독은 4명의 치료방사선과 의사에 의해서 시행되었으며 pelvic brim, sacrum, acetabulum, iliopectineal line, symphysis, ischium, obturator foramen, sacroiliac joint를 각각 very clear(1), clear(2), visible(3), not clear(4), not visible(5) 다섯 단계로 나누어 점수를 주었다. 결과 : video camera based EPID를 이용하여 얻은 영상을 비교하여 보았을 때 film을 이용한 port film과 enhancement를 시행하지 않은 portal image는 각 해부학적 구조에서는 차이를 보이지 않았다. 그러나 portal image를 window level로 영상의 변화를 주었을 때는 sacrum과 obturator는 영상의 판독에 도움이 되었다. 또한 portal image를 CLAHE로 enhance를 하였을 때는 모든 해부학적 구조물의 판독이 film보다 용이한 것으로 나타났다. matrix ion chamber type의 EPID를 이용하여 얻은 영상에서도 역시 port film과 영상의 변화를 주지 않은 portal image간에는 커다란 차이를 보이지 않았으나, portal image를 window level로 변화를 주었을 경우는 portal film에 비하여 영상의 질이 더욱 좋아지을 알 수 있었다. 결론 : 방사선 치료를 받는 환자 중에서 골반강의 영상에서는 EPID의 영상의 질은 기존의 port film과 비교하여 차이가 없었으며, window level로 영상에 변화를 주거나 enhance를 하였을 경우는 port film보다 더 나은 영상을 얻을 수 있어 기존의 port film을 대체 할 수 있을 것으로 생각된다.

분자선 증착법에 의해 성장한 MnTe 박막의 자기적 및 전기수송 특성

김우철,배성환,김삼진,김철성,김광주,윤정범,정명화,Kim, Woo-Chul,Bae, Sung-Whan,Kim, Sam-Jin,Kim, Chul-Sung,Kim, Kwang-Joo,Yoon, Jung-Bum,Jung, Myung-Hwa 한국자기학회 2007 韓國磁氣學會誌 Vol.17 No.2

분자선 증착법을 이용하여 MnTe 박막을 Si(100):B 및 Si(111) 기판 위에 성장시켰다. 두개의 K-cell을 사용하여 기판온도 $400^{\circ}C$ 및 Te가 풍부한 조건에서 MnTe 합성이 잘 이루어졌다. 이 경우 증착속도는 $1.1 {\AA}/s$이었고 성장된 층의 두께는 $700{\AA}$ 정도이었다. 합성된 MnTe 박막들에 대하여 X선회절, 초전도 양자 간섭계, Physical Property Measurement System, 홀효과 측정 등을 사용하여 그 구조적, 자기적, 전기적 특성들을 조사하였다. X선회절 측정 결과 Si(100) : B및 Si(111)기판 위에 성장된 MnTe는 다결정성의 hexagonal 구조를 나타내었으며, 자기적, 전기적 특성 측정 결과 분말형태의 MnTe와 비교하여 매우 다른 특성을 나타내었다. Zero-field-cooling(ZFC) 및 field-cooling(FC) 조건에서 취해진 자화율 측정에서 다결정 박막은 21 K, 49K, 210K 근처에서 자기적 전이 현상을 보였으며, ZFC와 FC 자화율 사이의 큰 불가역성이 나타났다. MnTe박막의 5K와 300K에서의 자기이력곡선은 강자성 상태를 나타내었으며 잔류자화값과 보자력은 5 K에서 $M_R= 3.5emu/cm^3$와 $H_c=55Oe$를, 300 K에서 $M_R= 2.1emu/cm^3$와 $H_c=44Oe$로 나타났다. 전기수송 특성 측정 결과, 온도에 따른 비저항은 저온에서 Mott variable range hopping 전도특성을 나타내는 전형적인 반도체 성질을 보여주었다. MnTe layers of high crystalline quality were successfully grown on Si(100) : B and Si(111) substrates by molecular beam epitaxy (MBE). Under tellurium-rich condition and the substrate temperature around $400^{\circ}C$, a layer thickness of $700{\AA}$ could be easily obtained with the growth rate of $1.1 {\AA}/s$. We investigated the structural, magnetic and transport properties of MnTe layers by using x-ray diffraction (XRD), superconducting quantum interference device (SQUID) magnetometry, and physical properties measurement system (PPMS). Characterization of MnTe layers on Si(100) : B and Si(111) substrates by XRD revealed a hexagonal structure of polycrystals with lattice parameters, ${\alpha}=4.143{\pm}0.001{\AA}\;and\;c=6.707{\pm}0.001{\AA}$. Investigation of magnetic and transport properties of MnTe films showed anomalies unlike antiferromagnetic powder MnTe. The temperature dependence of the magnetization data taken in zero-field-tooling (ZFC) and field-cooling (FC) conditions indicates three magnetic transitions at around 21, 49, and 210 K as well as the great irreversibility between ZFC and FC magnetization in the films. These anomalies are attributable to a magnetic-elastic coupling in the films. Magnetization measurements indicate ferromagnetic behaviour with hysteresis loops at 5 and 300 K for MnTe polycrystalline film. The coercivity ($H_c$) values at 5 and 300 K are 55 and 44 Oe, respectively. In electro-transport measurements, the temperature dependence of resistivity revealed a noticeable semiconducting behaviours and showed conduction via Mott variable range hopping at low temperatures.

S. P. Crown 치은연하부위(齒齦緣下部位)의 표면조도(表面租度)에 관(關)한 실험적(實驗的) 고찰(考察)

김우철,Kim, Woo-Chul 대한소아치과학회 1979 大韓小兒齒科學會誌 Vol.6 No.1

To evaluate the surface roughness of subgingival area of S. P. crown margins subjected to various polishing procedures, the study was performed by use of metallograph and surface roughness tester. The following results were obtained; 1) Abrasive stone wheel produced the roughest surface ($16.0{\mu}m$). 2) Final polish with rouge after polishing with rubber wheel, subsequent to abrasive stone wheel, produced the smoothest surface ($0.3{\mu}m$). 3) Both polish with rubber wheel after polshing with abrasive stone wheel, and polish with pumice (coarse$\rightarrow$medium$\rightarrow$fine) produced same surface roughness ($0.8{\mu}m$).

탈락기(脫落期) 유치치수(乳齒齒髓)의 미세구조(微細構造)에 관(關)한 전자현미경적(電子顯微鏡的) 연구(硏究)

김우철,Kim, Woo-Chul 대한소아치과학회 1983 大韓小兒齒科學會誌 Vol.10 No.1

With electron microscope, author studied on the pulp structure of human primary tooth in shedding stage. Non-carious human primary molar teeth were selected for this study. Using standard methods, specimens were sectioned and examined by light and electron microscope, The results were as follows; 1. In coronal pulp, odontoblasts were replaced by multinucleated odontoclasts, which contained a large number of mitochondria of varying shape and vacuoles in cytoplasm. Where odontoclasts were in contact with tooth surface, the characteristic ruffled border and clear zone were observed. 2. Fibrous tissue with plentiful collagen fibers and fibroblasts was observed adjacent to the dentin in the pulp. Fibroblast contained a number of mitochondria and well-developed rough-surfaced endoplasmic reticulum. 3. Inflammatory cells were observed in the pulp and active fibroblasts could be seen between inflammatory cells. In many cases, cervical epithelium proliferated toward absorbed area. 4. Inflammatory cells consisted of a number of lymphocytes, polymorphonuclear leukocytes, plasma cells and macrophages. Macrophage containing lysosomes in digestive state or phagocyting PMN could be seen. 5. In the primary molar of delayed root resorption, odontoblast layer, zone of Weil and cell-rich zone could be seen at roof of pulp chamber and odontoblast in this area cont과ained some lipid droplets.

CoFe1.9Y0.1O₄의 Sol-gel 합성과 자기적 성질 연구

김우철(Woo Chul Kim),김삼진(Sam Jin Kim),명보라(Bo Ra Myung),김진옥(Jin Ok Kim),윤성로(Sung Ro Yoon),김철성(Chul Sung Kim),윤성현(Sung Hyun Yoon) 한국자기학회 2001 한국자기학회 학술연구발표회 논문개요집 Vol.11 No.1

하상여과 모형에서 수평집수관의 조도계수

김우철(Woo Chul Kim),김승현(Seung Hyun Kim) 大韓環境工學會 2007 대한환경공학회지 Vol.29 No.2

Sol-gel법에 의한 초미세 분말 CoFe1.9Bi0.1O₄의 결정학적 및 자기적 성질 연구

김우철(Woo Chul Kim),김삼진(Sam Jin Kim),김철성(Chul Sung Kim),이승화(Seung Wha Lee) 한국자기학회 1999 韓國磁氣學會誌 Vol.9 No.4

Ultrafine CoFe_(1.9)Bi_(0.1)O₄ particles were fabricated by using a sol-gel method and their magnetic and structural properties were investigated with an x-ray diffractometer (XRD), a vibrating sample magnetometer (VSM), and a Mossbauer spectrometer. The result of x-ray diffraction and Mossbauer spectoscopy showed that the powders fired at and above 523 K had only cubic spinel structures. Mossbauer spectra measurements showed that the powders annealed at 523, 723, and 823 K possessed ferrimagnetic nature and paramagnetic nature due to superparamagnetism, simultaneously at room temperature and the powders annealed at and above 923 K behaved ferrimagneticaIly. In the case of the powder annealed at 923 K, the lattice constant was a_0=8.398±0.005 Å and the hyperfine fields were Hhf(A) = 479 kOe, Hhf(B) = 502 kOe. The isomer shifts indicate that the iron ions are ferric at tetrahedral[A] and octahedral sites [B], respectively. The magnetization as a function of annealing temperature increased as increasing annealing temperature. The lagest coercivity values were Hc=1368 Oe at 923 K annealing temperature. In the case of the powder annealed at 1123 K, the magnetization value was Ms=75 emu/g and this value was similler to that of CoFe₂O₄.

자궁경부 선암 환자에서 고선량률 강내치료와 저선량률 강내치료의 비교

김우철(Woo Chul Kim),김귀언(Gwi Eon Kim),정은지(Eun Ji Chung),서창옥(Chang Ok Suh),홍순원(Soon Won Hong),조영길(Young Kap Cho),노준규(John JK Loh) 대한방사선종양학회 2000 Radiation Oncology Journal Vol.18 No.1

목 적:자궁경부 선암은 발생률이 적어 편평상피암에 비하여 아직 치료방법에 대한 연구가 미흡하다. 또한 지금까지 저선량률 강내치료가 많이 사용되어 고선량률 강내치료의 결과는 많이 보고되고있지 않다. 따라서 저자들은 자궁경부 선암환자에서 고선량률 강내치료와 저선량률 강내치료를 비교하여 고선량률 강내치료의 효과를 알아보고자 하였다. 대상 및 방법:1971년 1월부터 1992년 12월까지 연세대학교 방사선종양학과에서 근치적 목적으로 치료된 106명의 자궁경부 선암 환자를 대상으로 하였다. 저선량률 강내치료는 35명에서 시행되었고, 71명은 고선량률 강내치료가 시행되었다. 저선량률군에서는 병기 1기가 8명, 병기 2기가 18명, 병기 3기가 9명이었고 외부방사선치료는 10 MV X-ray를 이용하여 매일 2 Gy씩 총 40∼64 Gy (중앙값 48Gy)가 조사되었다. 저선량률 강내치료는 radium 선원을 이용하여 Henshke applicator로 시행되었고 point A에 22∼59 Gy (중앙값 43 Gy)가 조사되었다. 고선량률군에서는 병기 1기가 16명, 병기 2기가 38명, 병기 3기가 17명 이었다. 외부방사선치료량은 40∼61 Gy (중앙값 45 Gy)이었고 분할선량은 1.8∼2.0Gy이었다. 고선량률 강내치료는 Co-60 선원을 사용하여 RALS (remote afterloading system)로 분할선량 3Gy를 주 3회 총 30∼57 Gy (중앙값 39 Gy)가 시행되었다. 결 과:저선량률군의 5년 생존률은 병기1, 2, 3기에서 각각 72.9, 61.9, 45.0%이었고 고선량률군에서는 각각 87.1, 58.3, 41.2% 이었다(p>0.05). 자궁경부 선암에서 고선량률군과 저선량률군간의 5년 생존률에는 차이가 없었다. 또한 양군간에 유의한 예후인자는 없었다. 고선량률군의 만성 합병증률은 26.8%로 저선량률군의 11.4%에 비하여 높았으나 대부분 grade I의 경미한 정도이었고 통계학적인 차이가 없어 받아들일 만한 결과이었다. 결 론:자궁경부 선암 환자에서 고선량률 강내치료는 저선량률 강내치료에 비하여 5년 생존률과 치료실패율에서 차이를 보이지 않아 저선량률 강내치료를 대치할 수 있을 것으로 생각되나 병기 2기와 3기에서 만성 합병증이 높아 분할 선량에 대한 연구가 필요할 것으로 생각된다. Purpose:The incidence of adenocarcinoma of the uterine cervix is low. Traditionally, Low Dose Rate (LDR) brachytherapy has been used as a standard modality in the treatment for patients with carcinoma of the uterine cervix. The purpose of this report is to evaluate the effects of the High dose rate (HDR) brachytherapy in the patients with adenocarcinoma of the uterine cervix compared with the LDR. Materials and Methods:From January 1971 to December 1992, 106 patients of adenocarcinoma of uterine cervix were treated with radiation therapy in the Department of Radiation Oncology, Yonsei University with curative intent. LDR brachytherapy was carried out on 35 patients and 71 patients were treated with HDR brachytherapy. In LDR Group, 8 patients were in stage I, 18 in stage II and 9 in stage III. External radiation therapy was delivered with 10 MV X-ray, daily 2 Gy fractionation, total dose 40∼46 Gy (median 48 Gy). And LDR Radium intracavitary irradiation was performed with Henschke applicator, 22∼59 Gy to point A (median 43 Gy). In HDR Group, there were 16 patients in stage I, 38 in stage II and 17 in stage III. The total dose of external radiation was 40∼61 Gy(median 45 Gy), daily 1.8∼2.0 Gy. HDR Co-60 intracavitary irradiation was performed with RALS (Remote Afterloading System), 30∼57 Gy (median 39 Gy) to point A, 3 times a week, 3 Gy per fraction. Results:The 5-year overall survival rate in LDR Group was 72.9%, 61.9%, 45.0% in stage I, II, III, respectively and corresponding figures for HDR were 87.1%, 58.3%, 41.2%, respectively (p>0.05). There was no statistical difference in terms of the 5-year overall survival rate between HDR Group and LDR Group in adenocarcinoma of the uterine cervix. There was 11% of late complication rates in LDR Group and 27% in HDR Group. There were no prognostic factors compared HDR with LDR group. The incidence of the late complication rate in HDR Group stage II, III was higher than that in LDR Group(16.7% vs. 31.6% in stage II, 11.1% vs. 35.3% in stage III, p>0.05). Although the incidence of radiation induced late complication rate was higher in HDR Group stage II and III patients than that in the LDR Group, statistical significance was not detected and within acceptable level. Conclusion:There was no difference in terms of 5-year survival rate and failure pattern in the patients with adenocarcinoma of the uterine cervix treated with HDR and LDR brachytherapy. Even late complication rates were higher in the HDR group it was an acceptable range. This retrospective study suggests that HDR brachytherapy seems to replace the LDR brachytherapy in the adenocarcinoma of the uterine cervix. However, further studies will be required to refine the dose rate effects.

간외 담도암에서 수술 후 방사선치료의 역할

김우철(Woo Chul Kim),이돈행(Don Haeng Lee),이건영(Keon Young Lee),이미조(Mi Jo Lee),김헌정(HunJung Kim),이석호(Suk Ho Lee),노준규(John JK Loh) 대한방사선종양학회 2003 Radiation Oncology Journal Vol.21 No.2

목 적: 간외 담도암에서 수술단독군과 수술 후 방사선치료가 시행된 군의 비교를 통하여 방사선치료의 역할을 알아보고자 한다. 대상 및 방법: 1997년 1월부터 2000년 12월까지 인하대 병원에서 근치적 절제술을 받은 41명의 간외 담도암 환자를 대상으로 하였다.이 중 22명의 환자는 수술 단독으로 치료 되었고(1군) 19명의 환자는 수술 후 방사선치료가 시행 되었다(2군). 수술은 완전절제가 시행된 경우가 1군에서는 11명(50%)이었고 2군에서는 7명(36.8%)이었다.나머지 환자는 절제연양성으로 현미경 적미세종양이 남아있었다.두 군 간에병기,수술방법,병리소견등의 분포의 차이는 없었다. 방사선치료는 10MV X-ray를 이용하여 45˜54Gy(중앙값: 50.4 Gy)를 원발종양과 주변 림프절에 조사하였다. 결 과: 1군에서는 국소실패한 환자가 12명(54.5%)인 반면 2군에서는 3명(15.8%)으로 수술단독군에서 국소실패율이 의미있게 높게 나타났으며(p=0.010), 1군에서 국소실패한 12명 중7명이 절제연 양성군에서 발생하였고 2군에서는 국소실패한 3명 모두가 절제연 양성에서 발생하여 완전 절제군보다 절제연 양성군에서 국소실패가 월등히 높았다.1군과 2군의 3년전체 생존율은 각각 38.3%, 38.9%이었고 3년 무병 생존율은 각각 18.8%와 26.3%로 통계학적 차이를 보이지 않았다. 그러나 절제연 양성인 환자에서는 3년 생존율이 24.2%와 36.4%로 방사선 치료군에서 좋았고(p=0.06) 절제연 양성인 환자의 3년 무병생존율은 18.2%와 25.0%로 통계학적으로도 의미 있게 방사선 치료군이 좋았다(p=0.04). 결 론:간외 담도암 환자에서 수술 후 방사선치료는 국소제어율을 높이며,특히 절제연이 양성인 환자에서는 생존율을 향상시킬 수 있을 것으로 생각한다. Purpose: The goal of this study was to determine the role of postoperative radiation therapy in extrahepatic bile duct cancers. Materials and Methods: Between 1997 and 2001, 41 patients with extrahepatic bile duct cancer having undergone surgical resection were retrospectively analyzed. Of the 41 patients, 22 were treated by surgeryalone(GroupI) with remaining 19 treated by surgery and postoperative radiation therapy(Group II). A gross total surgical resection with pathologically negative margins was performed in 11 of the patients (50%) in Group I, and in 7 of the patients (36.8%) in Group II. There were no significant differences in the disease stage, surgical procedure or pathological characteristics of the two groups. The patients in group II received 45˜54 Gy(median:50.4Gy)ofexternal beam radiation therapy to the tumor bed and draining nodal area. Results: The local failure rate was significantly higher in group I (54.5%) than in group II (15.8%)(p=0.010). Of the 12failed patients in Group Iand the 3 failed patients in group II,7 and 3 had a positive resection margin. The overall 3-year survival rates were 38.3 and 38.9% and the 3-year disease free survival rates were 18.8 and 26.3% in groups I andII,respectively. However, the patients with positive resection margins who received adjuvant radiation therapy had higher 3-year overall survival rates than those with surgery alone (36.4% vs. 24.2%, p=0.06), and 3-year disease free survival rate was significantly higher in the group II patients who had positive margins compared with those in group I (25.0% vs. 18.2%, p=0.04). Conclusion: Post operative adjuvant radiation therapy appeared to reduce the incidence of localfailure in patients with extrahepatic bile duct cancer, and might improve the survival rate in the patients with positive resection margins.