Kramer Gary H, Allen Steve A, Groff Dave
Human Monitoring Laboratory, Radiation Protection Bureau, 775 Brookfield Road, Ottawa, Ontario, Canada K1A 1C1.
Health Phys. 2003 Dec;85(6):751-8. doi: 10.1097/00004032-200312000-00021.
This paper describes the calibration of the new Cameco mobile lung counter and, more importantly, the problems encountered with recommendations for their long-term solution. The new Cameco lung counting system, which is based on an array of four 80-mm-diameter Canberra BeGe detectors, has used the JAERI phantom for its primary calibration as it more closely resembles ICRP reference data for lung dimensions compared with the LLNL phantom. Although the JAERI phantom's lung dimensions offer advantages over the LLNL phantom's lungs, this phantom is still not ideal. The work described in this paper leads to the conclusion that the LLNL be modified to more closely resemble the ICRP reference data if large area germanium detectors comprise the lung counter. Overlay plate stacking was necessary to achieve the range of chest wall thicknesses found within the Cameco work force (2-8 cm) when using the JAERI phantom. This technique has proved to be robust and is useful for extending the calibration range. Cameco is using group monitoring, which adds spectra to simulate very long counting times (10-20 h), and it is essential that all materials be low background. This was not initially the case here as found from overnight background counts.
本文描述了新型卡姆科移动肺部计数器的校准情况，更重要的是，阐述了所遇到的问题以及针对这些问题的长期解决方案建议。新型卡姆科肺部计数系统基于四个直径80毫米的堪培拉锗酸铋探测器阵列，在初次校准中使用了日本原子能研究所（JAERI）模型，因为与劳伦斯利弗莫尔国家实验室（LLNL）模型相比，它在肺部尺寸方面更接近国际辐射防护委员会（ICRP）的参考数据。尽管JAERI模型的肺部尺寸比LLNL模型的肺部具有优势，但该模型仍不理想。本文所述工作得出的结论是，如果肺部计数器采用大面积锗探测器，则需对LLNL模型进行修改，使其更接近ICRP参考数据。在使用JAERI模型时，需要叠加板堆叠才能达到卡姆科员工群体中发现的胸壁厚度范围（2至8厘米）。事实证明，该技术很可靠，有助于扩展校准范围。卡姆科采用分组监测，即添加能谱以模拟很长的计数时间（10至20小时），并且所有材料必须是低本底的，这一点至关重要。从过夜本底计数可以看出，最初这里并非如此。
