Journal of Radiation Protection and Research

  • 제32권1호
  • /
  • Pages.15-20
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  • 2007
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  • 2508-1888(pISSN)
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  • 2466-2461(eISSN)
대한방사선방어학회 (The Korean Association for Radiation Protection)
권호 표지

COMPUTATIONAL DETERMINATION OF NEUTRON DOSE EQUIVALENT LEVEL AT THE MAZE ENTRANCE OF A MEDICAL ACCELERATOR FACILITY

  • 발행 : 2007.03.30
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초록

An empirical formula fur the neutron dose equivalent at the maze entrance of medical accelerator treatment rooms was derived on the basis of a Monte Carlo simulation. The simulated neutron dose equivalents around the Varian medical accelerator by the MCNPX code were employed. Two cases of target rotational planes were considered: parallel and perpendicular to maze walls. Most of the maximum neutron dose equivalents at the doorway were found when the target rotational planes were parallel to maze walls and the beams were directed to the inner maze entrances. The neutron dose equivalents at the outer maze entrances were calculated for about 698 medical accelerator facilities which were generated from the geometry configurations of running treatment rooms, based on such gantry rotation that produces the maximum neutron dose at the doorway. The results calculated with the empirical formula in this study were compared with those calculated by the Kersey method for 7 operating facilities. It was found that the maximum disagreement between the calculation of this study and that of the Kersey method was a factor of 8.54 with the value calculated by the Kersey method exceeding that of this study. It was concluded that the kersey method estimated the neutron dose equivalent at the doorway computed by MCNPX more conservatively than this study technique.

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참고문헌

  1. Kersey RW. Estimation of neutron and gamma radiation in the entrance mazes of SL 75-20 linear accelerator treatment rooms. Medicamundi 1979;24(3):151-155
  2. French RL, Wells MB. An angle-dependent albedo for fast-neutron reflection calculations. Nucl. Sci. Eng. 1964;19:441-448 https://doi.org/10.13182/NSE64-A19002
  3. McCall RC, Jenkins TM and Shore RA. Transport of accelerator produced in a concrete room. IEEE Trans. Nucl. Sci. 1979;NS-26(1):1593-1597
  4. McCall RC, Jenkins TM, Shore RA and LaRiviere PD. Personnel hazards from medical electron accelerator photoneutrons. Proceeding of the 5th International Congress of the International Radiation Protection Association 1980;1:193
  5. McGinley PH, Elizabeth KB. Evaluation of neutron dose equivalent levels at the maze entrance of medical accelerator treatment rooms. Med. Phys. 1991;18(2):279-281 https://doi.org/10.1118/1.596713
  6. Knoll GF. Radiation detection and measurement. 2nd ed. New York;John Wiley & Sons, 1989:491
  7. NCRP, Neutron contamination from medical accelerators. NCRP 79, 1984
  8. Tosi G, Torresin A, Agosteo S, Foglio Para A, Sangiust V, Zeni L and Silari M. Neutron measurements around medical electron accelerators by active and passive detection techniques. Med. Phys. 1991;18(1):54-60 https://doi.org/10.1118/1.596751
  9. Waller EJ, Jamieson TJ, Cole D, Cousins T and Jammal RB. Experimental and computational determination of neutron dose equivalent around radiotherapy accelerators. Radiation Protection Dosimetry 2003;107(4):225-232 https://doi.org/10.1093/oxfordjournals.rpd.a006394
  10. Walter LS et al.. Monte carlo N-particle transport code system for multiparticle and high energy applications. Version 2.5.d. LA-UR-03-5916, 2003
  11. KIM HS. LEE JK. Assessment and measurement of the phetoneutron field produced in the Varian medical linear accelerator. Journal of NUCLEAR SCIENCE and TECHNOLOGY 2007 Jau;44(1):95-101 https://doi.org/10.3327/jnst.44.95
  12. ICRP, Conversion coefficients for use in radiological protection against external radiation. ICRP 74, 1997