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目的比较治疗计划系统二级准直器(MLC)角度选择对容积调强放射治疗(VMAT)计划质量与运行效率的影响,探索治疗计划设计的优化方案。方法随机选取2013年3月-12月治疗的20例鼻咽癌患者,设定不同的MLC角度,进行同步加量的VMAT逆向计划设计,比较MLC角度对靶区和危及器官剂量分布、机器输出跳数的差异。MLC角度分别设置为0、15、30、45、60°。结果随着MLC角度增大,靶区适形指数和均匀性指数有变差的趋势,0°和15°计划相对最优,45°和60°计划对危机器官的保护不如其他角度好而且机器跳数明显增加。结论改变MLC角度对治疗计划会产生明显影响,随MLC角度增加,计划质量与运行效率均有变差的趋势,但是小范围改变MLC角度理论上可以降低漏射线对人体的影响。
Objective To compare the impact of MLC angle selection on the quality and operation efficiency of volume modulated radiation therapy (VMAT) and explore the optimal plan of treatment planning. Methods Twenty patients with nasopharyngeal carcinoma who were treated from March to December in 2013 were randomly selected. The different MLC angles were set up and the VMAT reverse planning design was carried out. The dose distribution of the target area and organs at risk, the output of the machine The difference between the number of hops. MLC angle were set to 0,15,30,45,60 °. Results As the MLC angle increased, the target conformality index and uniformity index tended to deteriorate. The 0 ° and 15 ° plans were relatively optimal, while the 45 ° and 60 ° plans did not protect the organs at risk from other angles and the machines Hops increased significantly. Conclusion Changing the MLC angle has a significant impact on the treatment plan. As the MLC angle increases, the planning quality and operating efficiency tend to deteriorate. However, changing the MLC angle in a narrow range can theoretically reduce the impact of radiation leakage on the human body.