MU Fluence Reconstruction based-on Delivered Leaf Position: for IMRT Quality Assurance

세기조절방사선치료의 정도관리를 위한 모니터유닛 공간분포 재구성의 효용성 평가

  • Park, So-Yeon (Department of Radiation Applied Life Science, Seoul National University Graduate School) ;
  • Park, Yang-Kyun (Department of Radiation Applied Life Science, Seoul National University Graduate School) ;
  • Park, Jong-Min (Department of Radiation Applied Life Science, Seoul National University Graduate School) ;
  • Choi, Chang-Heon (Department of Radiation Applied Life Science, Seoul National University Graduate School) ;
  • Ye, Sung-Joon (Department of Radiation Oncology, Seoul National University College of Medicine)
  • 박소연 (서울대학교 대학원 방사선응용생명과학 협동과정) ;
  • 박양균 (서울대학교 대학원 방사선응용생명과학 협동과정) ;
  • 박종민 (서울대학교 대학원 방사선응용생명과학 협동과정) ;
  • 최창헌 (서울대학교 대학원 방사선응용생명과학 협동과정) ;
  • 예성준 (서울대학교 의과대학 방사선종양학교실)
  • Received : 2011.02.14
  • Accepted : 2011.03.22
  • Published : 2011.03.30

Abstract

The measurement-based verification for intensity modulated radiation therapy (IMRT) is a time-and labor-consuming procedure. Instead, this study aims to develop a MU fluence reconstruction method for IMRT QA. Total actual fluences from treatment planning system (TPS, Eclipse 8.6, Varian) were selected as a reference. Delivered leaf positions according to MU were extracted by the dynalog file generated after IMRT delivery. An in-house software was develop to reconstruct MU fluence from the acquired delivered leaf position data using MATLAB. We investigated five patient's plans delivered by both step-and-shoot IMRT and sliding window technologies. The total actual fluence was compared with the MU fluence reconstructed by using commercial software (Verisoft 3.1, PTW) and gamma analysis method (criteria: 3%/3 mm and 2%/1 mm). Gamma pass rates were $97.8{\pm}1.33$% and the reconstructed fluence was shown good agreement with RTP-based actual fluence. The fluence from step and shoot IMRT was shown slightly higher agreement with the actual fluence than that from sliding window IMRT. If moving from IMRT QA measurements toward independent computer calculations, the developed method can be used for IMRT QA. A point dose calculation method from reconstructed fluences is under development for the routine IMRT QA purpose.

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