4MV X-선을 이용한 조직보상체 두께비 연구 및 응용

A study on tissue compensator thickness ratio and an application for 4MV X-rays

  • 김영범 (고려대학교 의과대학 부속 안암병원 치료방사선과) ;
  • 정희영 (고려대학교 의과대학 부속 안암병원 치료방사선과) ;
  • 권영호 (고려대학교 의과대학 부속 안암병원 치료방사선과) ;
  • 김유현 (고려대학교 병설 보건전문대학 방사선과)
  • Kim Young-Bum (Department of Radiation Oncoloy, College of Medicine Korea University, Anam Hospital) ;
  • Jung Hee-Young (Department of Radiation Oncoloy, College of Medicine Korea University, Anam Hospital) ;
  • Kweon Young-Ho (Department of Radiation Oncoloy, College of Medicine Korea University, Anam Hospital) ;
  • Kim You-Hyun (Department of Radiotechnology, Junior College of Allied Health Science Korea University)
  • 발행 : 1996.11.01

초록

A radiation beam incident on irregular or sloping surface produces an inhomogeneity of absorbed dose. The use of a tissue compensator can partially correct this dose inhomogeneity. The tissue compensator should be made based on experimentally measured thickness ratio. The thickness ratio depends on beam energy, distance from the tissue compensator to the surface of patient, field size, treatment depth, tissue deficit and other factors. In this study, the thickness ratio was measured for various field size of $5cm{\times}5cm,\;10cm{\times}10cm,\;15cm{\times}15cm,\;20cm{\times}20cm$ for 4MV X-ray beams. The distance to the compensator from the X-ray target was fixed, 49cm, and measurement depth was 3, 5, 7, 9 cm. For each measurement depth, the tissue deficit was changed from 0 to(measurement depth-1)cm by 1cm increment. As a result, thickness ratio was decreased according to field size and tissue deficit was increased. Use of a representative thickness ratio for tissue compensator, there was $10\%$ difference of absorbed dose but use of a experimentally measured thickness ratio for tissue compensator, there was $2\%$ difference of absorbed dose. Therefore, it can be concluded that the tissue compensator made by experimentally measured thickness ratio can produce good distribution with acceptable inhomogeneity and such tissue compensator can be effectively applied to clinical radiotherapy.

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