在容积拉弧调强治疗中，制作放疗方案的主要方法是直接子野优化方法，其中最为关键的步骤是如何快速地生成一个合理的子野形状。本项目针对现有子野形状生成算法中出现的问题展开如下研究：研究和分析已有直接子野优化算法中影响算法精度和计算量的因素，构造一种新的子野形状生成算法框架，提高算法精度和减少计算量；针对直接子野优化方法收敛速度较慢和频繁出现增加\删除子野的问题，研究不同的搜索方向对直接子野优化算法收敛性的影响，寻求最佳的构造搜索方向的方法；利用病人解剖结构的信息，结合容积拉弧调强治疗旋转照射方式的特点，提出一种新的子野形状修正算法，进一步提高算法精度和简化方案；研究多页准直器叶片的伴影和凸凹槽效应对子野剂量计算的影响，构造剂量修正模型，提高方案优化质量。该项目的研究将图像处理方法和运筹学等理论引入到子野形状生成过程中，改善了直接子野优化方法的性能，同时也为直接子野优化算法的研究提供新的视点。

In volumetric modulated arc therapy (VMAT), the main way used to make VMAT treatment plan is the direct aperture optimization (DAO) algorithm, in which the aperture shape algorithm plays an important role. The purpose of this study is to solve some key problems in aperture shape algorithm as follows. In order to improve the DAO algorithm and save the computation time, a new aperture shape algorithm is put forward by studying and analyzing the factors affecting the accuracy and the computation complexity of the DAO algorithm. By analyzing the relationship between the search direction and the convergence of DAO algorithm, a new method forming the search direction is proposed to overcome the drawback of the slow convergence of objection functions and the problems of adding\deleting aperture frequently. Combining characteristics of the rotary radiation for VMAT, a new aperture shape algorithm based on the patient anatomy is presented to improve the precision and simplify the treatment plan. To reduce the influencers from the shadow and the tongues and grooves of multi-leaf collimators, a new model is applied to improve the quality of treatment plan. By applying the theory from the image processing method and the operations research to the aperture shape algorithm, it improves the DAO algorithm and provides a new perspective to the study of the DAO method.