Radiation Oncology Journal

The Korean Society for Radiation Oncology (대한방사선종양학회)
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Feasibility Study of the Real-Time IMRT Dosimetry Using a Scintillation Screen

고감도 형광판을 이용한 실시간 선량측정 가능성 연구

  • Lim Sang Wook (Department of Radiation Oncology, Asan Medical Center, College of Medicine, University of Ulsan) ;
  • Yi Byong Yong (Department of Radiation Oncology, Asan Medical Center, College of Medicine, University of Ulsan) ;
  • Ko Young Eun (Department of Radiation Oncology, Asan Medical Center, College of Medicine, University of Ulsan) ;
  • Ji Young Hoon (Department of Radiation Oncology, Korea Institute of Radiological & Medical Sciences Medicine) ;
  • Kim Jong Hoon (Department of Radiation Oncology, Asan Medical Center, College of Medicine, University of Ulsan) ;
  • Ahn Seung Do (Department of Radiation Oncology, Asan Medical Center, College of Medicine, University of Ulsan) ;
  • Lee Sang Wook (Department of Radiation Oncology, Asan Medical Center, College of Medicine, University of Ulsan) ;
  • Shin Seong Soo (Department of Radiation Oncology, Asan Medical Center, College of Medicine, University of Ulsan) ;
  • Kwon Soo-Il (Department of Medical Physics, Kyonggi University) ;
  • Choi Eun Kyoung (Department of Radiation Oncology, Asan Medical Center, College of Medicine, University of Ulsan)
  • 임상욱 (울산대학교 의과대학 서울아산병원 방사선종양학과) ;
  • 이병용 (울산대학교 의과대학 서울아산병원 방사선종양학과) ;
  • 고영은 (울산대학교 의과대학 서울아산병원 방사선종양학과) ;
  • 지영훈 (원자력의학원 방사선종양학과) ;
  • 김종훈 (울산대학교 의과대학 서울아산병원 방사선종양학과) ;
  • 안승도 (울산대학교 의과대학 서울아산병원 방사선종양학과) ;
  • 이상욱 (울산대학교 의과대학 서울아산병원 방사선종양학과) ;
  • 신성수 (울산대학교 의과대학 서울아산병원 방사선종양학과) ;
  • 권수일 (경기대학교 의학물리학과) ;
  • 최은경 (울산대학교 의과대학 서울아산병원 방사선종양학과)
  • Published : 2004.03.01
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Abstract

Purpose : To study the feasibility of verifying real-time 2-D dose distribution measurement system with the scintillation screen for the quality assurance. Materials and Methods : The water phantom consisted of a scintillation screen (LANEX fast screen, Kodak, USA) that was axially located in the middle of an acrylic cylinder with a diameter of 25 cm. The charge-coupled device (CCD) camera was attached to the phantom In order to capture the visible light from the scintillation screen. To observe the dose distribution In real time, the intensity of the light from the scintillator was converted to a dosage. The isodose contours of the calculations from RTP and those of the measurements using the scintillation screen were compared for the arc therapy and the Intensity modulated radiation therapy (IMRT). Results : The kernel, expressed as a multiplication of two error functions, was obtained in order to correct the sensitivity of the CCD of the camera and the scintillation screen. When comparing the calculated isodose and measured isodose, a discrepancy of less than 8 mm in the high dose region was observed. Conclusion : Using the 2-D dosimetry system, the relationship between the light and the dosage could be found, and real-time verification of the dose distribution was feasible.

목적 : 고감도형광판을 이용하여 2차원적인 선량분포를 실시간으로 얻을 수 있는 quality assurance (QA) 장치의 개발 가능성을 알아보고자 한다. 대상 및 방법 : 고감도형광판을 삽입한 직경 25 cm의 물 팬톰을 제작하였으며 여기에 charge-coupled device (CCD) 카메라를 부착하여 방사선조사 시 형광판에서 발생되는 가시광선에 의한 영상을 얻었고 영상이 가지고 있는 세기정보를 계산하여 픽셀값에 따른 선량분포를 실시간으로 확인하였다. 회전치료 및 세기조절방사선치료를 각각 수행하여 형광판으로부터 얻은 등선량곡선을 치료계획장치에서 계산된 등선량곡선과 비교하였다 결과 : 선량당 빛의 세기의 관계그래프를 이용하여 형광판과 CCD의 감도 보정을 위한 커널(kernel)을 구하였는데 두 개의 에러함수 곱으로 표현할 수 있었다. 회전치료(Arc Therapy)와 intensity modulated radiation therapy (IMRT)에서 형광판으로 측정한 등선량곡선과 치료계획장치에서 계산된 등선량분포 비교에서 고선량에서 최대 8 mm 이내의 오차를 보였다. 결론 : 본 연구에서 개발한 2차원 선량계를 이용하여 물팬톰에서 선량과 빛의 세기와의 관계 및 방사선 조사시간과 빛의 양의 관계를 찾을 수가 있었고 세기조절방사선치료 QA를 위한 실시간 평면선량계로서의 사용 가능성을 보였다.

Keywords

References

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