Yu Jin Hao, Hong Zhou Ling, Wen Lv Qing, Min Chen Chao, Jie Chen Guang
Department of Biomedical Engineering, Southern Medical University, Guangzhou 510515 China (phone: +86 02061648290-15; fax: +86 02061648291; e-mail:
Conf Proc IEEE Eng Med Biol Soc. 2005;2005:7091-4. doi: 10.1109/IEMBS.2005.1616140.
It is showed that the empirical scatter-radius function (Day function) used to generate the equivalent-field tables is a good approximation to the results of normalized scatter-air ratios extracted from the British Journal of Radiology (BJR) beam data for depths up to 10 cm. Accuracy can be improved by making the Day function depend on depth. Equivalent squares, determined by sector integration of the original or modified Day functions, are suitable for megavoltage photon-beam dose calculations in irregular as well as rectangular fields. We make further simplification for the functions to calculate equivalent squares by no use of scatter dose data that is often difficult to get for hospitals. The simplified method has the same accuracy compared to the original or modified Day functions.
结果表明，用于生成等效野表的经验散射半径函数（Day函数）与从《英国放射学杂志》（BJR）束流数据中提取的深度达10 cm的归一化散射空气比结果非常近似。通过使Day函数依赖于深度，可提高准确性。通过对原始或修正后的Day函数进行扇形积分确定的等效方野，适用于不规则野以及矩形野的兆伏级光子束剂量计算。我们进一步简化了计算等效方野的函数，无需使用医院通常难以获取的散射剂量数据。与原始或修正后的Day函数相比，简化方法具有相同的准确性。
