Contamination of the 6MV Linear Accelerator Photon Beam by Electrons

6MV 전자 선형 가속기 광자선의 전자오염

  • Yoo, Meong-Jin (Department of Therapeutic Radiology, Pusan National University Hospital) ;
  • Kim, Dong-Won (Department of Therapeutic Radiology, Pusan National University Hospital) ;
  • Chung, Woon-Hyuk (Department of Physics, Pusan National University)
  • 유명진 (부산의대 부속병원 치료방사선과) ;
  • 김동원 (부산의대 부속병원 치료방사선과) ;
  • 정운혁 (부산대학교 자연과학대학 물리학과)
  • Published : 1988.06.20


The 6 MV photon beam of a linear accelerator (Mevatron 67) was studied for electron contamination. The surface dose, attributable almost entirely to contamination electrons, has a linear dependence on field width for square fields and an inverse square dependence on distance from the bottom of the fixed head assembly. Build-up and surface dose measurements were taken with and without an acrylic blocking tray in place. Further measurements were made with a copper filter designed to reduce secondary electrons emitted by photon interactions with the acrylic tray. The results are discussed in relation to skin sparing effect for radiation therapy patients. To achieve the maximum skin sparing effect, the selection of the optimum SSD and TSD is needed.