MOSFET Dosimetry for Evaluation of Gonad Shielding during Radiotherapy

방사선 치료시 생식선 차폐체 성능 평가를 위한 MOSFET 선량 측정

  • Kim, Hwi-Young (Department of Radiation Applied Life Science, Seoul National University College of Medicine) ;
  • Choi, Yun-Seok (Department of Radiation Applied Life Science, Seoul National University College of Medicine) ;
  • Park, So-Yeon (Department of Radiation Applied Life Science, Seoul National University College of Medicine) ;
  • Park, Yang-Kyun (Department of Radiation Applied Life Science, Seoul National University College of Medicine) ;
  • Ye, Sung-Joon (Department of Radiation Oncology, Seoul National University College of Medicine)
  • 김휘영 (서울대학교 의과대학 방사선응용생명 협동과정) ;
  • 최윤석 (서울대학교 의과대학 방사선응용생명 협동과정) ;
  • 박소연 (서울대학교 의과대학 방사선응용생명 협동과정) ;
  • 박양균 (서울대학교 의과대학 방사선응용생명 협동과정) ;
  • 예성준 (서울대학교 의과대학 방사선종양학교실)
  • Received : 2011.02.11
  • Accepted : 2011.03.24
  • Published : 2011.03.30

Abstract

In order to confirm feasibility of MOSFET modality in use of in.vivo dosimetry, evaluation of gonad shielding in order to minimize gonadal dose of patients undergoing radiotherapy by using MOSFET modality was performed. Gonadal dose of patients undergoing radiotherapy for rectal cancer in the department of radiation oncology of Seoul National University Hospital since 2009 was measured. 6 MV and 15 MV photon beams emitted from Varian 21EX LINAC were used for radiotherapy. In order to minimize exposed dose caused by the scattered ray not only from collimator of LINAC but also from treatment region inside radiation field, we used box.shaped lead shielding material. The shielding material was made of the lead block and consists of $7.5\; cm\;{\times}\;9.5\;cm\;{\times}5.5\;cm$ sized case and $9\;cm\;{\times}\;9.5\;cm\;{\times}\;1\;cm$ sized cover. Dosimetry for evaluation of gonad shielding was done with MOSFET modality. By protecting with gonad shielding material, average gonadal dose of patients was decreased by 23.07% compared with reference dose outside of the shielding material. Average delivered gonadal dose inside the shielding material was 0.01 Gy. By the result of MOSFET dosimetry, we verified that gonadal dose was decreased by using gonad shielding material. In compare with TLD dosimetry, we could measure the exposed dose easily and precisely with MOSFET modality.

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