Williamson J F
Department of Radiation Oncology, University of Arizona, Tucson 85724.
Int J Radiat Oncol Biol Phys. 1988 Jul;15(1):227-37. doi: 10.1016/0360-3016(88)90372-0.
This paper presents dose-rate tables and treatment planning data needed to accurately implement the Sievert line-source integral, found on most commercial computer-aided treatment planning systems, for two recently introduced 137Cs intracavitary sources. One source uses a high-density active core designed to reproduce the non-elliptical isodose curves characteristic of the traditional radium tube. The other source consists of two or three discrete 137Cs seeds encapsulated in stainless steel. Using Monte Carlo dose-rate calculations as the standard of accuracy, we show that the Sievert model, using conventionally defined filtration corrections, overestimates kerma-rate in free space by as much as 20%. In addition, tissue attenuation and scatter build-up factors, derived from an isotropic point source, do not accurately characterize the distribution of scatter dose about heavily filtered sources. By varying the input parameters of the Sievert line-source integral so as to optimize its agreement with the more rigorous Monte Carlo data, accuracy of 3% can be achieved.
本文给出了剂量率表和治疗计划数据，这些数据是精确实施西弗特线源积分所必需的，大多数商业计算机辅助治疗计划系统中都有该积分，用于两种最近推出的铯-137腔内放射源。一种放射源采用高密度活性芯，旨在重现传统镭管特有的非椭圆形等剂量曲线。另一种放射源由封装在不锈钢中的两颗或三颗离散铯-137籽源组成。以蒙特卡罗剂量率计算作为准确性标准，我们表明，使用传统定义的过滤校正的西弗特模型在自由空间中对比释动能率的高估高达20%。此外，从各向同性点源导出的组织衰减和散射积累因子，不能准确表征重过滤放射源周围散射剂量的分布。通过改变西弗特线源积分的输入参数，以优化其与更严格的蒙特卡罗数据的一致性，可以实现3%的精度。
