연세대 / 한민철, 홍채선*, 김진성*
Abstract
This study assesses the dosimetric leaf gap (DLG) correction factor in Mobius3D commissioning affected by a couch top platform and calculates the optimal DLG value according to the point dose difference function. DLG optimizations were performed for 3 LINAC machines and a total of 30 patient volumetric modulated arc therapy plans (i.e., 10 plans per each LINAC). Point dose calculations were performed using an automatic dose calculation system in Mobius3D as well as Mobis3D calculation using a Mobius Verification Phantom (MVP)-based quality assurance plan with a carbon fiber couch top. Subsequently, the results were compared with measurement data. The averaged point dose measured for the MVP with a couch top decreased by approximately 2% relative to that without the couch top. The average of the optimal DLG factors increased by 1.153 mm due to the couch top effect for a dose decrease of 2% at the measured point. In the procedure of Mobius beam commissioning, users should adjust the DLG correction factor using a specific phantom (including MVP) with a couch top structure. If the DLG optimization were performed by using MVP automatic dose calculation system, the factor should be increased by approximately 1.2 mm per 2% dose difference considering user's couch top effect.
본 그림은 Mobius3D에서 commissioning 및 QA 용으로 제작된 전용 팬텀(MVP)에 본원에서 사용하는 Couch top을 추가하여 선량계산된 모습을 보여줍니다.
Affiliations
Min Cheol Han 1 , Jihun Kim 1 , Chae-Seon Hong 2 , Kyung Hwan Chang 1 , Su Chul Han 1 , Kwangwoo Park 1 , Dong Wook Kim 1 , Myoung Kyu Park 3 , Yu Yun Noh 3 , Jin Sung Kim 4
1 Department of Radiation Oncology, Yonsei University College of Medicine, 50-1 Yonsei-ro, Seodaemun-gu, Seoul, South Korea.
2 Department of Radiation Oncology, Yonsei University College of Medicine, 50-1 Yonsei-ro, Seodaemun-gu, Seoul, South Korea. cs.hong@yuhs.ac.
3 Department of Radiation Oncology, Yonsei Cancer Center, Seoul, South Korea.
4 Department of Radiation Oncology, Yonsei University College of Medicine, 50-1 Yonsei-ro, Seodaemun-gu, Seoul, South Korea. jinsung@yuhs.ac.
편집위원
근래의 방사선치료 환자정도관리로 epid 측정값이나 MLC position의 log 기록을 이용하여 간접적인 계산방식으로 수행하는 경우가 증가하고 있고, 이에 따라 관련 소프트웨어를 도입하는 병원도 증가하고 있는데, 이러한 소프트웨어중의 하나인 Mobius3D를 사용할 때 고려해야 할 부분을 잘 분석하고 대안을 제시한 것 같음
2020-10-05 17:45:10