대한방사선치료학회지 (The Journal of Korean Society for Radiation Therapy)
- 제19권1호
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- Pages.1-5
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- 2007
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- 1598-8449(pISSN)
On Board Imager (OBI)를 이용한 Setup Error 분석에 대한 연구
Analyses of the Setup Errors using on Board Imager (OBI)
- 김종덕 (화순전남대학교병원 방사선종양학과) ;
- 이행오 (화순전남대학교병원 방사선종양학과) ;
- 유재만 (화순전남대학교병원 방사선종양학과) ;
- 지동화 (화순전남대학교병원 방사선종양학과) ;
- 송주영 (화순전남대학교병원 방사선종양학과)
- Kim, Jong-Deok (Department of Radiation Oncology, Chonnam National University Hwasun Hospital) ;
- Lee, Haeng-O (Department of Radiation Oncology, Chonnam National University Hwasun Hospital) ;
- You, Jae-Man (Department of Radiation Oncology, Chonnam National University Hwasun Hospital) ;
- Ji, Dong-Hwa (Department of Radiation Oncology, Chonnam National University Hwasun Hospital) ;
- Song, Ju-Young (Department of Radiation Oncology, Chonnam National University Hwasun Hospital)
- 발행 : 2007.03.31
초록
목적: 방사선치료 시 OBI (on board imager) 시스템으로 환자 셋업 오차(set-up error)를 확인, 보정한 결과를 분석하여, 셋업 오차(set-up error)의 경향 및 원인을 살펴보고, 기존 필름과 EPID (electronic portal imaging device)를 사용한 방법에 비해 OBI의 정확성과 유용성에 대하여 알아보고자 한다. 대상 및 방법: 2006년 3월부터 2006년 5월까지 본원에 내원한 3차원 치료계획 환자 130명을 대상으로 주 1회 이상 OBI를 이용하여 치료전 셋업 영상의 분석을 시행하였다. 직각으로 획득한 2개의 영상을 모의 치료실에서 획득한 기준영상(reference image)과 합성(Fusion) 후 분석을 하였다. 분석 후 Vertical, Lateral, Longitudinal 방향으로 변위(Shift)거리를 측정하여 오차를 분석했다. 또한, 주요 부위별, 방향별로 구분하여 셋업 오차(set-up error) 요인들을 비교, 평가하였다. 결과: OBI를 적용하여 분석한 환자 41.5%에서 변위가 없이 Setup이 정확하였고, 52.3%에서
Purpose: The accuracy and advantages of OBI(On Board Imager) against the conventional method like film and EPID for the setup error correction were evaluated with the analysis of the accumulated data which were produced in the process of setup error correction using OBI. Materials and Methods: The results of setup error correction using OBI system were analyzed for the 130 patients who had been planned for 3 dimensional conformal radiation therapy during March 2006 and May 2006. Two kilo voltage images acquired in the orthogonal direction were fused and compared with reference setup images. The setup errors in the direction of vertical, lateral, longitudinal axis were recorded and calculated the distance from the isocenter. The corrected setup error were analyzed according to the lesion and the degree of shift variations. Results: There was no setup error in the 41.5% of total analyzed patients and setup errors between 1mm and 5mm were found in the 52.3%. 6.1% patients showed the more than 5mm shift and this error were verified as a difference of setup position and the movement of patient in a treatment room. Conclusion: The setup error analysis using OBI in this study verified that the conventional setup process in accordance with the laser and field light was not enough to get rid of the setup error. The KV images acquired using OBI provided good image quality for comparing with simulation images and much lower patients' exposure dose compared with conventional method of using EPID. These advantages of OBI system which were confirmed in this study proved the accuracy and priority of OBI system in the process of IGRT(Image Guided Radiation Therapy).