Korean Journal of Digital Imaging in Medicine (대한디지털의료영상학회논문지)

The Korean Society for Digital Imaging in Medicine (대한디지털의료영상학회)
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Stem Effect Correction Factor of Ionization Chamber in Exposure Measurements of High Energy Photons

고 에너지 광자선의 조사선량 측정 시 전리함의 스템효과 보정계수

  • Park, Cheol-Woo (Department of Radiological Technology, Dongeui Institute of Technology) ;
  • Lee, Jae-Seung (Department of Radiation Oncology, Good Samaritan Hospital) ;
  • Kweon, Dae-Chel (Department of Radiological Science, Shinheung College University) ;
  • Cha, Dong-Soo (Department of Radiation Oncology, Yeungnam University Hospital) ;
  • Kim, Jin-Soo (Department of Radiation Oncology, Bundang-Cha University Hospital) ;
  • Kim, Kyoung-Keun (Department of Radiological Technology, Daegu Polytechnic College University)
  • 박철우 (동의과학대학 방사선과) ;
  • 이재승 (한동대학교 선린의료원 방사선종양학과) ;
  • 권대철 (신흥대학 방사선과) ;
  • 차동수 (영남대학교병원 방사선종양학과) ;
  • 김진수 (차의과학대학 분당차병원 방사선종양학과) ;
  • 김경근 (대구산업정보대학 방사선과)
  • Received : 2010.04.20
  • Accepted : 2010.05.25
  • Published : 2010.05.31
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Abstract

Ionization chambers often exhibit a stem effect, caused by interactions of radiation with air near the chamber end, or with dielectric in the chamber stem or cable. In this study measured stem effect correction factor for length of ionization chamber from medical linear accelerator recommend to with the use of stem correction method. For a model of the Farmer-type chamber, were used to calculate the beam quality correction factor. These interactions contribute to the apparent measured exposure. Additionally, it needs to consider ionization chamber use of small volume and stem effect of cable by a large field. Linear accelerator generated photons energy and increased dose repeatedly measured by using stem correction method. Stem effect was dependence of the energy and increases with photon energy conditions improved of beam quality. In conclusion, stem effect correction factor was measured within 0.4% calculated according to the exposures stem length and also supposed to determined below 1% of another stem correction method.

Keywords