| 胡家成,杨小元,杨元第,樊铁栓,黄斐增,刘鉴常,孙吉宁,叶卫国.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,2005,25(6):561-564 |
| 球形石墨空腔电离室壁修正因子的测量与验证 |
| Measurement and verification of wall correction factor for the spherical graphite cavity chamber |
| 投稿时间：2005-06-27 |
| DOI： |
| 中文关键词: 空腔电离室 空气比释动能 壁修正因子Kwall 蒙特卡罗模拟 |
| 英文关键词:Cavity chamber Air kerma Wall correction factor (Kwall) Monte Carlo calculations |
| 基金项目:国家自然科学基金资助项目(10275058) |
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| 中文摘要: |
| 目的 探讨球形石墨空腔电离室壁修正因子(Kwall)的确定方法。方法 用实验外推方法测量NIM10cm3和NIM30cm3球形石墨空腔电离室在60Coγ射线下的壁修正因子Kwall,并且采用Monte Carlo(MC)模拟计算方法对实验得出的壁修正因子Kwall结果进行验证。结果 实验和计算结果的比较表明,对于NIM10cm3和NIM30cm3球形石墨空腔电离室,采用传统的“几何厚度”外推法确定的壁修正因子比MC模拟计算结果偏低约1.0%,而采用“等效平均厚度“外推法与”.模拟计算结果在0.45%内吻合。对美国标准技术研究院(National Institute of Standards and Technology NIST)的国家空气比释动能基准组中的NIST30cm3和NIST50cm3球形石墨空腔电离室在60Coγ射线下的壁修正因子Kwall进行了MC模拟计算,计算结果与NIST发布的值在0.06%内吻合。结论 实验外推和MC计算方法所得到的球形石墨空腔电离室在60Coγ射线下的壁修正因子Kwall结果与国外其他国家基准实验室结果相符合。 |
| 英文摘要: |
| 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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