非匀速优化旋转治疗的理论和实验研究

Theoretical and Experimental Studies of Non uniform Speed Optimized Rotational Radiotherapy

目的提出一种非匀速优化旋转治疗方法，从剂量学角度研究了其可行性。方法包括优化治疗剂量分布计算和实验两部分。在剂量计算中，设计了一个用于合理调节射束旋转速率的优化因子，并用半适形野取代单一野，以利于改善剂量分布。将优化方法加进基本数学模型中，以大量实验数据为基础，设计完成了剂量计算法和相应Ｃ程序。结果引入优化方法后，剂量分布得到显著改善。结论本文提出的优化方法能够在一定程度上解决中心横截面上的适形问题；这一初步结论可为下一步研究———采用变频技术控制机架旋转速率，将该方法运用到直线加速器和６０Ｃｏ治疗机上提供了必要的剂量学参考。

Objective A method of non uniform speed optimized rotation therapy was proposed,and the feasibility was studied from dosimetrical angle.Methods The study content is divided into two parts:the dose distribution calculation of the optimized therapy and the experiment. The optimization factor designed for rotation speed and quasi conformal field was used to improve the dose distribution.The two optimizations are added into the basical math model.An algorithm and the responding C program are designed on the basis of great amount of experimental data.Results The results of the dose calculation pre and post being optimized show that the dose distributions are remarkably improved by the optimization. Conclusion From the theoretical calculation and experimental results,by using non uniform speed rotational irradiation we may partially solve the problem of conformation on the horizontal axis (mid plane).By using the variable frequency technique to control the rotation speed our technique will be easily applied to accelerator or 60 Co therapy machine.