Objective:To discuss influences of the setting of control point number for plan when Monaco5.11 plan system formulated volumetric modulated arc therapy (VMAT) plan of nasopharyngeal carcinoma.Methods: 10 patients with nasopharyngeal carcinoma were optimized by single arc through adopting the setting of 100 and 120 control point number, respectively. A series of indexes in planning target region and endangered organs, such as dose distribution, monitor units, control point number, therapy time, comformity index and homogeneity index in the target region, and other evaluation indexes, were compared and researched.Results: Both of the two setting could satisfy the requirement of clinical dosage, and the difference of dose distribution between target region and endangered organs was no significant(P>0.05). The average monitor units, control point number and therapy time of 100 control point number setting were respectively 93.5％, 85.2％ and 92.4％ of those of 120 control point number setting.Conclusion: When Monaco5.11 is used to formulate nasopharyngeal carcinoma single arc VMAT plan, the plan of 100 control point number setting can reduce monitor units, control point number and therapy time in the premise of meeting the requirement of clinical dosage.%目的:探讨Monaco5.11计划系统制定鼻咽癌容积旋转调强放射治疗(VMAT)计划时控制点数量设定对计划的影响.方法:对10例鼻咽癌患者分别采用100和120的控制点进行单弧优化,比较两者所得计划的靶区和危及器官的剂量分布、机器跳数、控制点数量、治疗时间、靶区的适形指数和均匀指数等指标.结果:两者所得计划均能满足临床剂量要求,靶区和危及器官的剂量分布无统计学意义(P>0.05),100控制点所得计划的平均机器跳数、控制点数量和治疗时间分别是120控制点和所得计划的93.5％、85.2％和92.4％.结论:Monaco5.11计划系统制定鼻咽癌单弧VMAT计划时,100控制点所得计划能在满足临床剂量要求的前提下减少机器跳数、控制点数量和治疗时间.
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