调强放射治疗中角度优化必要性的研究

用模拟动力学最优化方法，研究了在调强放射治疗（IMRT）中角度优化的必要性。作者在一个模拟体模上，采用9，7，5和3束照射方式，从不同角度共面照射，然后采用模拟动力学最优化方法进行调强优化计算。在最优化计算中，考虑了对紧要器官的硬约束和体积约束。在优化完成后记录政线一组参数下的目标函数、剂量体积直方图（DVH曲线）、强度分布和剂量分布。通过比较不同射束角度设置下的DVH曲线表明：在9束照射时，不需进行角度优化；但7，5，3束照射时，有必要进行角度优化。

The Study on the Necessity of Beam Orientation Optimization in Intensity-Modulated Radiotherapy

The necessity of beam orientation optimization in intensity modulated radiotherapy is discussed by using the simulated dynamics algorithm for optimization of intensity profiles. A simulated phantom is used as a testing sample. On the sample, nine,seven,five and three coplanar beams are irradiated respectively at different orientation configurations and the optimization intensity profiles are calculated by the simulated dynamics. In the intensity profile optimization, hard constraints or volume constraints have been taken into account. Once a optimization is finished,the DVH,intensity profiles and dose distributions for every beam configurations are recorded. By comparing the results obtained under different orientation configurations, a conclusion is reached that it is unnecessary to optimize beam orientation in case of nine beams, while orientation optimization is necessary for cases of less beams.