中文摘要：

由于子野分割带来的误差,使得调强放疗（Intensity-Modulated Radiation Therapy,简称IMRT）计划系统所制作的计划往往不能满足临床要求。本研究将采用基于共轭梯度法的子野权重优化方法来减小此误差,提高制作计划的效率和效果。采用共轭梯度法优化子野权重和微调子野形状,最终使得子野分割前后强度误差最小。在精确放疗系统中对常见的临床病例（鼻咽癌和周围性肺癌）进行测试,通过对比靶区和危及器官的剂量体积直方图以及CT片上的等剂量线,发现子野权重优化后靶区的平均剂量分别从87.0%提高到100.2%和从90.0%提高到98.4%,更好地满足临床要求。

英文摘要：

The error caused by leaf sequencing often leads to planning of Intensity-Modulated Radiation Therapy（IMRT） arrange system couldn＇t meet clinical demand.The optimization approach in this paper can reduce this error and improve efficiency of plan-making effectively.Conjugate Gradient algorithm was used to optimize segment weight and readjust segment shape,which could minimize the error anterior-posterior leaf sequencing eventually.Frequent clinical cases were tasted by precise radiotherapy system,and then compared Dose-Volume histogram between target area and organ at risk as well as isodose line in computed tomography（CT） film,we found that the effect was improved significantly after optimizing segment weight.Segment weight optimizing approach based on Conjugate Gradient method can make treatment planning meet clinical request more efficiently,so that has extensive application perspective.