| HU Jia-cheng,YANG Xiao-yuan,YANG Yuan-di,et al.Measurement and verification of wall correction factor for the spherical graphite cavity chamber[J].Chinese Journal of Radiological Medicine and Protection,2005,25(6):561-564 |
| Measurement and verification of wall correction factor for the spherical graphite cavity chamber |
| Received:June 27, 2005 |
| DOI： |
| KeyWords:Cavity chamber Air kerma Wall correction factor (Kwall) Monte Carlo calculations |
| FundProject:国家自然科学基金资助项目(10275058) |
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| Abstract:: |
| Objective To discuss the method how to identify wall correction factor (Kwall). Methods The paper introduce how to use extrapolation of the ionization current measured for different wall thickness by the spherical graphite cavity chamber whose volume is 10 cm3 and 30 cm3 for 60Co γ-rays. The wall correction factors were determined by this method and Monte Carlo(MC) calculations. Results The results of the present experiment and calculation indicated that the wall correction factor determined by traditional geometry thickness extrapolation method was 1.0% less than that by MC calculation.The result of applying the equivalent mean thickness to calculate with extrapolation method and that of MC calculation were accordable within 0.45%.The relative dose and wall correction factors for the spherical graphite cavity chamber whose volume is 30 cm3 and 50 cm3 of the standards of air kerma of the NIST for 60Co γ-rays were calculated by MC calculation,and the calculation results were in accordance with the published values of NIST within 0.06%. Conclusion The spherical graphite cavity chamber wall correction factor determined by traditional extrapolation method and MC calculation is accordable with the results of foreign labs (PSDL). |
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