Williamson J F
Department of Radiation Oncology, University of Arizona, Tucson 85724.
Med Phys. 1988 Sep-Oct;15(5):686-94. doi: 10.1118/1.596181.
To clinically utilize relative three-dimensional dose distribution data for 125I seeds in water, the specific dose constant must be known. This constant is the ratio of absolute dose rate in medium, 1 cm from the source on its transverse bisector, to source strength. We have used the Monte Carlo method to calculate specific dose constants in water for three types of 125I seeds (models 6711, 6701, and 6702). Our photon transport code realistically models the complex internal structure of these interstitial sources as well as the exposure standardization experiments conducted at the National Bureau of Standards which form the basis of 125I source strength specification. In addition, relative attenuation factors for the three seed types are presented. Our results indicate that published data overestimate the specific dose constant by 10% to 14%.
为了在临床上利用水中¹²⁵I 种子的相对三维剂量分布数据，必须知道特定剂量常数。这个常数是介质中距源横向平分线1厘米处的绝对剂量率与源强度的比值。我们使用蒙特卡罗方法计算了三种类型¹²⁵I 种子（6711型、6701型和6702型）在水中的特定剂量常数。我们的光子传输代码逼真地模拟了这些组织间源的复杂内部结构以及在国家标准局进行的构成¹²⁵I 源强度规范基础的照射标准化实验。此外，还给出了这三种种子类型的相对衰减因子。我们的结果表明，已发表的数据将特定剂量常数高估了10%至14%。
