Abstract：To discuss how to use nominal 10 cm3 cylindrical cavity ionization chamber to give absolute measurement to the Cs-137 air kerma. The wall correction factor kwall and the axial non-uniformity correction factor kan is determined by both the experimental method and Monte Carlo (MC) calculation. The results showed, the wall correction factor kwall determined by geometry thickness extrapolation method is less than 0.091% compared with that by the MC calculation, the axial non-uniformity correction factor kan determined by the experimental method is less than 0.63% compared with that by the MC calculation. The error between the two values is acceptable. The repeated experiment will inevitably introduce other error factors, and MC calculation method is simple and high repeatability. Eventually we selected MC calculation results for kwall, kan value.
［1］阿蒂克斯 F H, 罗奇 W C. 辐射剂量学: 第1卷［M］.北京:原子能出版社,1981.
［2］韩奎初.测量照射量(空气比释动能)的空腔电离室［J］.核标准计量与质量,1995,(1):33-35.
［3］Kessler C, Roger P, Allisy-Roberts P J, et al. Comparison of the standards for air kerma of the KRISS and the BIPM for 137Cs gamma radiation［J］. Metrologia, 2010, 47(S): 06022.
［4］Allisy-Roberts P J, Kessler C, Toni M, et al. Comparison of the standards for air kerma of the ENEA-INMRI and the BIPM for 137Csγrays［R］. Rapport BIPM-2010/7,2010.
［5］Allisy-Roberts P J, Burns D T, Takate N, et al. Comparison of the standards for air kerma of the NMIJ and the BIPM for 137Cs γ rays［R］. Rapport BIPM-2004/12,2004.
［6］邬蒙蒙,李德红,杨元第.参与BIPM RI（I）-K5比对的基准［J］.计量学报,2011,32（z1）:36-40.
［7］Rogers D W O, Treurniet J. Monte Carlo calculated wall and axial non-uniformit corrections for primary standards of air kerma［R］. NRCC Report PIRS-663,1999.
［8］Loftus P T, Weaver J T. Standardization of 60Co and 137Cs Gamma-Ray Beams in Terms of Exposure［J］.J Res Nat Bureau Stand-A Phys and chem, 1974,78(A):465-476.
［9］Rogers D W O, Bielajew A F, Nahum A E. Ion chamber response and Awall, correction factors in 60Co beam by Monte Carlo simulation［J］. Phys Med Biol,1985,30(5):429-443.
［10］胡家成,杨小元,杨元第,等. 球形石墨空腔电离室壁修正因子的测量与验证［J］.中华放射医学与防护杂志,2005,12（25）,561-564.
［11］胡家成,杨小元,杨元第,等.球-圆柱形空腔电离室壁修正因子的实验测量［J］.计量学报,2007,28（Z1）: 256-260.
2016, Vol. 37 
