MONTE CARLO SIMULATIONS FOR A VARIAN CLINAC 2100C ACCELERATOR

DOI
  • ARAKI Fujio
    Department of Radiological Technology, Kumamoto University School of Health Sciences

Bibliographic Information

Other Title
  • 医用加速器Varian Clinac 2100Cのモンテカルロシミュレーション
  • ―4MVと10MV-X線の線量分布, エネルギースペクトル, 角度分布, フルエンス分布, 平均エネルギー分布の分析―
  • —DOSE DISTRIBUTION, ENERGY SPECTRA, ANGULAR SPREAD, FLUENCE PROFILES AND MEAN ENERGY PROFILES OF 4 AND 10 MV PHOTON BEAMS—

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Description

This study shows detailed characteristics of realistic radiotherapy photon beams: dose distribution, energy spectra, angular spread, fluence profiles and mean energy profiles. It provides more comprehensive information for radiotherapy photon beams including incident photons and primary photons as well as contaminating electrons and positrons in a radiation beam for different field sizes and beam energies. The EGSnrc Monte Carlo code, BEAMnrc has been used to simulate 4 and 10 MV photon beams from a Varian Clinac 2100C accelerator. A simulated realistic beam is stored in a phase space files, which contains details of each particle's complete history including where it has been and where it has interacted. The phase space files are used to calculate depth-dose components from different particles and surface dose and contribution from different particles to surface dose across the filed. Energy spectra, angular spread, fluence profiles and mean energy profiles at the phantom surface for each particle are also obtained using the phase space information. The accuracy of a simulated beam is validated by the excellent agreement between the Monte Carlo calculated and measured dose distributions except for 10 MV at the 40×40 cm2 field in the build-up region. Measured depth-dose curves are obtained from depth-ionization curves by accounting for the stopping-power ratios for realistic beams. At 4 MV, the contaminant charged particles contribute 6% to 26% of maximum dose at the surface when the field size increases from 10×10 to 40×40 cm2. Similarly, their contributions at 10 MV are up to 7% and 23% of maximum dose at the surface for 10×10 cm2 and 40×40 cm2 fields, respectively. However, the fluence of these contaminant charged particles is less than 1.0% of incident photon fluence in all cases.

Journal

  • The Journal of JASTRO

    The Journal of JASTRO 17 (2), 53-63, 2005

    Japanese Society for Therapeutic Radiology and Oncology

Keywords

Details 詳細情報について

  • CRID
    1390282679306810112
  • NII Article ID
    130004497064
  • DOI
    10.11182/jastro.17.53
  • ISSN
    18819885
    10409564
  • Text Lang
    ja
  • Data Source
    • JaLC
    • CiNii Articles
  • Abstract License Flag
    Disallowed

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