Sakelliou L, Sakellariou K, Sarigiannis K, Angelopoulos A, Perris A, Zarris G
Physics Department, University of Athens, Greece.
Phys Med Biol. 1992 Oct;37(10):1859-72. doi: 10.1088/0031-9155/37/10/004.
Simple analytical functions derived from our point source Monte Carlo calculations on the combined attenuation and scatter factor, B exp(-mu r), for 60Co, 137Cs, 198Au, 192Ir, 241Am, 125I (models 6702 and 6711) brachytherapy sources and the nuclide 99Tcm, for water spherical geometries of radii R = 15 and 20 cm, are presented. Our results for the broadly used 60Co, 137Cs, 198Au and 192Ir brachytherapy sources can be compared directly and found in excellent agreement with the widely accepted data of Meisberger et al in the limited distance range for which the latter are valid. Our data, however, can be used with high accuracy outside this distance range. Many discrepancies observed among different data sets available in recent literature are attributable to differences in geometries used. The results for the recently introduced 241Am source are very dissimilar to those produced by any other currently used brachytherapy source. Dose rate distributions, based on the above simple functions, are proposed in accordance with the recommendations for calibration of the brachytherapy sources in terms of reference air kerma rate and were found to be in good agreement with data available in the literature. Our calculations for 125I sources (models 6702 and 6711), provided that the characteristic x-rays from titanium encapsulation are taken into account, support recent experimental and theoretical dose rate distributions indicating that currently accepted values for 125I may be overestimated.
本文给出了从点源蒙特卡罗计算得出的简单解析函数，该计算针对60Co、137Cs、198Au、192Ir、241Am、125I（型号6702和6711）近距离治疗源以及核素99Tcm，在半径R = 15和20 cm的水球几何模型中，计算了组合衰减和散射因子B exp(-μr)。我们对于广泛使用的60Co、137Cs、198Au和192Ir近距离治疗源的结果，可以直接与Meisberger等人在其有效有限距离范围内被广泛接受的数据进行比较，发现二者高度吻合。然而，我们的数据可在该距离范围之外高精度使用。近期文献中不同数据集之间观察到的许多差异归因于所使用几何模型的不同。最近引入的241Am源的结果与目前使用的任何其他近距离治疗源产生的结果非常不同。根据近距离治疗源以参考空气比释动能率进行校准的建议，基于上述简单函数提出了剂量率分布，发现其与文献中的数据吻合良好。我们对125I源（型号6702和6711）的计算，前提是考虑到钛封装产生的特征x射线，支持了近期的实验和理论剂量率分布，表明目前公认的125I值可能被高估。
