한국 국회예산권 강화방안에 관한 연구 : 국회의 예산편성과정에의 참여를 중심으로

학위논문(석사)--서울대학교 행정대학원 :행정학과 정책학전공,1998.Maste

Liver tumor margin analysis using MVCT (Mega-Voltage Computed Tomography) image

의학과/석사[한글] 간종양의 방사선치료시 셋업오차, 호흡에 의한 횡격막 움직임과 장기의 기하학적 변형 등으로 인하여 전통적인 관점에서 종양의 실제 위치를 파악하는데 제약이 있어 왔다. 본 연구에서는 토모테라피 영상유도장치인 MVCT (Mega-voltage Computed Tomography) 영상을 이용하여 자유 호흡시 종양경계상태를 파악하여 종양 위치의 변화 양상을 알아보고자 하였다.2006 년 4 월부터 2007 년 8 월까지 간종양에 토모테라피를 받은 환자 26 명을 대상으로 치료 시작 후 10 회까지 매회 치료시의 MVCT 영상을 분석하였다. 1차적으로 골격 구조에 따라 셋업오차보정을 한 상태에서 종양경계부위의 위치 변화를 치료계획 kVCT (Kilo-Voltage Computed Tomography)와의 영상융합을 통해 비교하여 오차 정도를 파악하였다. 이 때 2차원 직교좌표계 상에서 종양부위에서 치료계획 kVCT와 MVCT 간의 최대 간격이 있는 부분을 기준으로 길이를 측정하였으며 간종양의 위치별 변화 양상을 보기 위하여 종양 위치를 Couinaud’s proposal을 기준으로 1 군 (S1), 2 군 (S2, S3, S4), 3 군 (S5, S6), 4 군 (S7, S8)으로 나누어 각 군별 위치 변화 양상을 비교하였다. 분석에는 Tomotherapy Hi-Art system 2.0 (Tomotherapy, USA)을 이용하였다.MVCT를 통해 알아본 평균 셋업오차는 각각 0.45 ± 2.04 mm (left-right), 0.97 ± 4.06 mm (cranial-caudal), 8.38 ± 4.67 mm (anterior-posterior) 이었다. 종양 위치에 따른 위치 변화 양상은 각 군별 관련성 보다는 환자의 개별적 특성이 중요한 인자인 것으로 나타난 가운데 2 군이 전방 바깥쪽으로 2.80 mm, 좌측 안쪽으로 2.23 mm 차이를 나타내어 1, 3, 4 군에 비해 특징적인 경향을 보였고, 4 군은 전, 후, 좌, 우 차이의 편차가 심했으며 1, 2, 3 군 모두 후방으로의 위치 변화는 1 mm 전후로 적은 값을 갖는 경향성을 나타내었다.결론적으로 간종양에 토모테라피를 적용할 때 MVCT를 이용하여 종양 위치에 따른 움직임이 다양함을 확인할 수 있었으며 이를 적절한 PTV (Planning Target Volume) 여백의 설정에 이용한다면 향후 간종양의 정밀 방사선치료를 구현하는데 유익할 것으로 생각된다. [영문]In liver tumor radiotherapy, there are some limitations such as setup errors, liver motions and geometrical deformation by respiration. Many studies have been done about liver motions. Mostly they are done by 2-dimensional analysis. Therefore, we tried to analyze the liver motions, setup errors, and each relationship by mega-voltage computed tomography, a 3-dimensional tomotherapy image-guided system.There were 26 patients who were treated for liver tumors by tomotherapy from Apr 2006 to Aug 2007. Most patients have hepatocellular carcimoma, some intrahepatic cholangioncarcinoma, and some metastatic liver tumor. We analyzed MVCT (Mega-Voltage Computed Tomography) image of each patient from 1st to 10th fraction. There were 2 steps in the analysis. First, we corrected setup error of each fraction by bony landmark. And second, we compared the tumor margin difference between the simulation kVCT (Kilo-Voltage Computed Tomography) image and MVCT image of each fraction in corrected setup status so that we could get tumor margin shift length data in each fraction. All data were set in the 2-dimensional right angle coordinate system of the transverse section of each patient’s body and anterior, posterior, right, left shift lengths were measured by maximum shift length between kVCT and MVCT image. For craniocaudal margin difference, we used the diaphragmatic motion by 2 dimensional fluoroscopy because of rough MVCT images of coronal and sagittal view. We classified 4 groups by Couinard’s 8 segments to assess motion pattern of each group. Group 1 is composed of patients with segment 1 lesion, group 2 segment 2, 3, 4 lesion, group 3 segment 5, 6 lesion, group 4 segment 7, 8 lesion. We used Varian Ximatron for diaphragmatic motion images and Tomotherapy Hi-Art system 2.0 (Tomotherapy, USA) for MVCT analyses.Mean length of the setup differences were 0.45 ± 2.04 mm for left-right, 0.97 ± 4.06 mm for cranial-caudal, 8.38 ± 4.67 mm for anterior-posterior direction. Tumor motions according to tumor locations were relatively noticeable in group 2 and group 4. In group 2, anterior mean shift length was 2.80 mm outwards, left mean shift length was 2.23 mm inwards. In group 4, anterior, posterior, left, right mean shift lengths were quite irregular and in group 1, 2, 3, posterior mean shift lengths were around 1 mm.Through setup error data and tumor margin shift data, we verified the various motion patterns according to the liver tumor locations. Mean values did not show significant results, but patient-specific geometric variations due to internal target motions and daily setup errors (considered separately in the study) were more important than population average motion. Different and indivdualized assess may be needed in PTV margin expansion of the liver tumor when the tumor is located in different groups. In conclusion, the MVCT analysis is useful for proper PTV margin and precision radiotherapy.ope

Second primary brain tumors following cranial irradiation for pediatric solid brain tumors

PURPOSE: We describe our institution's experience with seven patients who developed second brain tumors following cranial irradiation. METHODS: The median age at first irradiation was 8 years (range, 3-20 years). Initial diagnoses were two cases of germinoma, one non-germinomatous germ cell tumor (NGGCT), three cases of medulloblastoma, and one pineal gland tumor (pathology undetermined). All patients received craniospinal irradiation followed by local boost and the median dose to the initial tumor area was 54.0 Gy (range, 49.8-60.6 Gy). Four patients (two medulloblastomas, one germinoma, and one NGGCT) received chemotherapy. RESULTS: Second brain tumors were diagnosed a median of 114 months (range, 64-203) after initial radiation. Pathologic diagnoses were one glioblastoma, two cases of anaplastic astrocytoma, one medulloblastoma, one low-grade glioma, one high-grade glial tumor, and one atypical meningioma. Five patients underwent surgical resection with subsequent radiotherapy. One anaplastic astrocytoma patient received chemotherapy only following stereotactic biopsy. The meningioma patient was alive 32 months after total resection and radiosurgery for subsequent recurrences. Six patients died within 18 months and most deaths were due to disease progression. CONCLUSIONS: Most patients diagnosed with second brain tumors had received high-dose, large-volume radiotherapy with chemotherapy at a young age. Further studies are required to determine the relationship between radiotherapy/chemotherapy and the development of secondary brain tumors.ope

Is there a clinical benefit to adaptive planning during tomotherapy in patients with head and neck cancer at risk for xerostomia?

OBJECTIVES: To evaluate the necessity of adaptive planning in helical tomotherapy (TOMO) for head and neck cancer in terms of dosimetric influence on the parotid gland. METHODS: Thirty-one patients underwent curative TOMO for head and neck cancer from April 2006 to April 2007. For each patient, neck diameter was monitored together with body weight at first cervical spine level through mega-voltage computed tomography during the TOMO course. Ten of 31 patients, with significant weight loss (>5%) and/or neck diameter decrease (>10%), were selected for dosimetric analysis, and parotid dose was recalculated at the fourth and last week of TOMO. Xerostomia was estimated by Radiation Therapy Oncology Group criteria. RESULTS: The median dose was 69.96 Gy (range, 54 to 69.96 Gy) and there was no grade 3 or greater complication. Ten patients with significant neck diameter decrease and/or weight loss showed frequent grade 2 acute xerostomia (P=0.02). The volume percentage of daily fractional dose over 0.75 Gy for the parotid gland (V0.75 Gy) increased by 23.6% at the end of TOMO. CONCLUSIONS: For patients with significant anatomic contour change; neck diameter decrease (>10%) or weight loss (>5%), adaptive planning using mega-voltage computed tomography can identify dosimetric changes and reduce deleterious side effects such as xerostomia.ope