Radiation Oncology Journal

The Korean Society for Radiation Oncology (대한방사선종양학회)
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Radiation Dose Accuracy 81 the Isocenter : Standard Stereotactic Radiosurgery Technique Developed at Seoul National University Hospital

서울대학교병원형 방사선수술 표준기법의 중심점 선량의 오차

  • Shin Seong Soo (Department of Therapeutic Radiology, Institute of Radiation Medicine, Medical Research Center, Seoul National University College of Medicine) ;
  • Kim Il Han (Department of Therapeutic Radiology, Institute of Radiation Medicine, Medical Research Center, Seoul National University College of Medicine) ;
  • Ha Sung Whan (Department of Therapeutic Radiology, Institute of Radiation Medicine, Medical Research Center, Seoul National University College of Medicine) ;
  • Park Charn Il (Department of Therapeutic Radiology, Institute of Radiation Medicine, Medical Research Center, Seoul National University College of Medicine) ;
  • Kang Wee-Saing (Department of Therapeutic Radiology, Institute of Radiation Medicine, Medical Research Center, Seoul National University College of Medicine) ;
  • Hur Sun Nyung (Department of Therapeutic Radiology, Institute of Radiation Medicine, Medical Research Center, Seoul National University College of Medicine)
  • 신성수 (서울대학교 의과대학 치료방사선과학교실, 의학연구원 방사선의학연구소) ;
  • 김일한 (서울대학교 의과대학 치료방사선과학교실, 의학연구원 방사선의학연구소) ;
  • 하성환 (서울대학교 의과대학 치료방사선과학교실, 의학연구원 방사선의학연구소) ;
  • 박찬일 (서울대학교 의과대학 치료방사선과학교실, 의학연구원 방사선의학연구소) ;
  • 강위생 (서울대학교 의과대학 치료방사선과학교실, 의학연구원 방사선의학연구소) ;
  • 허순녕 (서울대학교 의과대학 치료방사선과학교실, 의학연구원 방사선의학연구소)
  • Published : 2002.12.01
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Abstract

Purpose : To confirm the accuracy of the radiation dose at the isocenter by the standard linear accelerator-based stereotactic radiosurgery technique which was developed at Seoul National University Hospital. Materials and Methods : Radiation dosimetry was undertaken during standard 5-arc radiosurgery using 6 MV X-ray beam from CL2100C linac. The treatment head was attached with circular tertiary collimators of 10 and 20 mm diameter. We measured the absorbed dose at the isocenter of a multi-purpose phantom using two kinds of detector : a 0.125 co ionization chamber and a silicon diode detector. Results : The dose differences at each arc plane between the planned dose and the measured dose at the isocenter raged from $-0.73\%\;to\;-2.69\%$ with the 0.125 cc ion chamber, and from $-1.29\%\;to\;-2.91\%$ with the diode detector during radiosurgery with the tertiary collimator of 20 mm diameter. Those with the 10-mm tertiary collimator ranged from $-2.39\%\;to\;-4.25\%$ with the diode. Conclusion : The dose accuracy at the isocenter was ${\pm}3\%$. Therefore, further efforts such ws modification in processing of the archived image through DICOM3.0 format are required to lessen the dose difference.

목적 : 서울대학교병원에서 개발한 정위방사선수술 시스템에서의 표준적 정위방사선수술기법을 적용시 중심점에서의 방사선량 오차를 확인하고자 하였다. 재료 및 방법 : 내경 10 mm 20 mm인 원통형의 3차 콜리메이터를 장착후 5개의 호형(arc)으로 구성된 표준형 정위방사선수술계획에 따라 시행한 정위방사선수술시의 선량을 측정하였다. 방사선은 CL2100C 선형가속기에서 발생하는 6 MV X-선을 사용하였고 자체 개발한 다용도 팬톰에서 0.125 cc 전리함 및 다이오드 검출기로 중심점 선량을 측정하였다. 결과 : 내경 20 mm인 3차 콜리메이터를 장착한 정위방사선수술 시행시 호형에 따른 계획선량과 측정선량 간 오차는 0.125 cc 전리함 측정시 $-0.73\%$ 내지 $-2.69\%$, 다이오드 검출기 측정시 $-1.29\%$ 내지 $-2.91\%$이었다. 내경 10 mm 인 3차 콜리메이터 장착한 경우의 오차는 다이오드 검출기로 측정하였을 때 $-2.39\%$ 내지 $-4.25\%$이었다. 결론 : 중심점 선량 오차는 약 $3\%$ 정도로서 DICOM 3.0 표준형식을 통한 영상자료 처리 등의 개선책을 통한 최소화 노력이 필요하다.

Keywords

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