한국의학물리학회지:의학물리 (Progress in Medical Physics)

  • 제24권4호
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  • Pages.271-277
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  • 2013
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  • 2508-4445(pISSN)
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  • 2508-4453(eISSN)
한국의학물리학회 (Korean Society of Medical Physics)
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Convolution-Superposition 알고리즘을 이용한 치료계획시스템에서 공기가 포함된 표적체적에 대한 IMRT 플랜: 전립선 케이스

Convolution-Superposition Based IMRT Plan Study for the PTV Containing the Air Region: A Prostate Cancer Case

  • 강세권 (한림대학교 의과대학 방사선종양학교실) ;
  • 윤제웅 (한림대학교 의과대학 방사선종양학교실) ;
  • 박소아 (한림대학교 의과대학 방사선종양학교실) ;
  • 황태진 (한림대학교 의과대학 방사선종양학교실) ;
  • 정광호 (한림대학교 의과대학 방사선종양학교실) ;
  • 한태진 (한림대학교 의과대학 방사선종양학교실) ;
  • 김해영 (한림대학교 의과대학 방사선종양학교실) ;
  • 이미연 (한림대학교 의과대학 방사선종양학교실) ;
  • 김경주 (한림대학교 의과대학 방사선종양학교실) ;
  • 배훈식 (한림대학교 의과대학 방사선종양학교실)
  • Kang, Sei-Kwon (Department of Radiation Oncology, Hallym University College of Medicine) ;
  • Yoon, Jai-Woong (Department of Radiation Oncology, Hallym University College of Medicine) ;
  • Park, Soah (Department of Radiation Oncology, Hallym University College of Medicine) ;
  • Hwang, Taejin (Department of Radiation Oncology, Hallym University College of Medicine) ;
  • Cheong, Kwang-Ho (Department of Radiation Oncology, Hallym University College of Medicine) ;
  • Han, Taejin (Department of Radiation Oncology, Hallym University College of Medicine) ;
  • Kim, Haeyoung (Department of Radiation Oncology, Hallym University College of Medicine) ;
  • Lee, Me-Yeon (Department of Radiation Oncology, Hallym University College of Medicine) ;
  • Kim, Kyoung Ju (Department of Radiation Oncology, Hallym University College of Medicine) ;
  • Bae, Hoonsik (Department of Radiation Oncology, Hallym University College of Medicine)
  • 투고 : 2013.12.06
  • 심사 : 2013.12.13
  • 발행 : 2013.12.31
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초록

전립선에 대한 IMRT 치료계획을 작성 시 CTV를 확장해서 PTV를 얻을 때 가끔 직장 내의 공기가 포함되는 경우가 있는데, 공기의 처리 여부에 따라 선량 처방에 문제가 발생한다. 이 경우 IMRT 플랜의 최적화 과정에서 다음과 같은 세 가지 가능성을 생각해 볼 수 있다: PTV에 포함된 공기를 원래의 공기밀도로 두는 경우('airOpt'), 포함된 공기의 밀도를 조직과 비슷하게 밀도 1로 하는 경우('density1Opt'), 공기 부분을 제외한 PTV를 고려하는 경우('noAirOpt'). 본 연구에서는 이 세가지 경우에 대해 7개 방향에서 10 MV 광자선으로 동일한 인자의 IMRT 플랜을 하였다. 평가를 위해서는 CTV를 복사한 후, PTV 내에서 직장 쪽으로 이동시켜 최악의 표적 위치 설정이 되도록 원래의 공기가 있는 부분에 위치하도록 해서 가상의 CTV를 만들었다. PTV의 선량커버(dose coverage)와 최대 선량값을 비교했을 때, density1Opt 플랜만이 임상적으로 적절하였다. airOpt 경우, PTV에 과도한 선량이 전달되었고 선량전달체적 또한 과도하였다. noAirOpt 경우에는 이동된 가상 CTV 위치에서 저선량을 보였다. 이 결과에 의하면, 전립선 IMRT 플랜의 작성에서 공기가 포함된 PTV의 경우 플랜의 최적화와 선량 처방을 하기 전에, PTV에 포함된 공기의 밀도를 밀도값 1로 변경하는 것이 적절하였다. 이 아이디어는 두경부 IMRT 플랜을 비롯하여, 표적체적 내에 공기가 포함된 기타 경우에도 그대로 적용가능한 것으로 판단되며, 추가연구를 진행 중이다.

In prostate IMRT planning, the planning target volume (PTV), extended from a clinical target volume (CTV), often contains an overlap air volume from the rectum, which poses a problem inoptimization and prescription. This study was aimed to establish a planning method for such a case. There can be three options in which volume should be considered the target during optimization process; PTV including the air volume of air density ('airOpt'), PTV including the air volume of density value one, mimicking the tissue material ('density1Opt'), and PTV excluding the air volume ('noAirOpt'). Using 10 MV photon beams, seven field IMRT plans for each target were created with the same parameter condition. For these three cases, DVHs for the PTV, bladder and the rectum were compared. Also, the dose coverage for the CTV and the shifted CTV were evaluated in which the shifted CTV was a copied and translated virtual CTV toward the rectum inside the PTV, thus occupying the initial position of the overlap air volume, simulating the worst condition for the dose coverage in the target. Among the three options, only density1Opt plan gave clinically acceptable result in terms of target coverage and maximum dose. The airOpt plan gave exceedingly higher dose and excessive dose coverage for the target volume whereas noAirOpt plan gave underdose for the shifted CTV. Therefore, for prostate IMRT plan, having an air region in the PTV, density modification of the included air to the value of one, is suggested, prior to optimization and prescription for the PTV. This idea can be equally applied to any cases including the head and neck cancer with the PTV having the overlapped air region. Further study is being under process.

키워드

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피인용 문헌

  1. Dosimetric effects of the acuros XB and anisotropic analytical algorithm on volumetric modulated arc therapy planning for prostate cancer using an endorectal balloon vol.10, pp.None, 2013, https://doi.org/10.1186/s13014-015-0346-3
  2. Comparison of dosimetric and radiobiological parameters on plans for prostate stereotactic body radiotherapy using an endorectal balloon for different dose-calculation algorithms and delivery-beam mod vol.70, pp.4, 2013, https://doi.org/10.3938/jkps.70.424