Radiation Oncology Journal

The Korean Society for Radiation Oncology (대한방사선종양학회)
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A Study on Design and Application of Tissue Compensator for 6MV X-rays

6MV X-선에 대한 조직 보상체의 제작 및 응용에 관한 연구

  • Chai Kyu Young (Department of Therapeutic Radiology, College of Medicine, Seoul National University) ;
  • Choi Eun Kyung (Department of Therapeutic Radiology, College of Medicine, Seoul National University) ;
  • Chung Woong Ki (Department of Therapeutic Radiology, College of Medicine, Seoul National University) ;
  • kang Wee Saing (Department of Therapeutic Radiology, College of Medicine, Seoul National University) ;
  • Ha Sung Whan (Department of Therapeutic Radiology, College of Medicine, Seoul National University) ;
  • Park Charn Il (Department of Therapeutic Radiology, College of Medicine, Seoul National University)
  • 채규영 (서울대학교 의과대학 치료방사선과학교실) ;
  • 최은경 (서울대학교 의과대학 치료방사선과학교실) ;
  • 정웅기 (서울대학교 의과대학 치료방사선과학교실) ;
  • 강위생 (서울대학교 의과대학 치료방사선과학교실) ;
  • 하성환 (서울대학교 의과대학 치료방사선과학교실) ;
  • 박찬일 (서울대학교 의과대학 치료방사선과학교실)
  • Published : 1989.06.01
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Abstract

A radiation beam incident on an irregular or sloping surface produces the non-uniformity of absorded dose. The use of a tissue compensator can partially correct this dose inhomogeneity. The tissue compensator is designed based on the patient's three dimensional contour. After required compensator thickness was determined according to tissue deficit at $25cm\pm25cm$ field size, 10cm depth for 6MV x-rays, tissue deficit was mapped by isoheight technique using laser beam system. Compensator was constructed along the designed model using 0.8mm lead sheet or 5mm acryl plate. Dosimetric verification were peformed by film dosimetry using humanoid phantom. Dosimetric measurements were normalized to central axis full phantom readings for both compensated and non-compensated field. Without compensation, the percent differences in absorbed dose ranged as high as $12.1\%$ along transverse axis, $10.8\%$ along vertical axis. With the tissue compensators in place, the difference was reduced to $0\~43\%$ Therefore, it can be concluded that the compensator system constructed by isoheihnt technique can produce good dose distribution with acceptible inhomogeneity, and such compensator system can be effectively applied to clinical radiotherapy.

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