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清华大学学报(自然科学版)  2015, Vol. 55 Issue (7): 744-749    
  机械工程 本期目录 | 过刊浏览 | 高级检索 |
确定旋转放疗设备等中心点的平均矢量算法
张翔, 樊文刚, 史少华, 叶佩青, 张辉
清华大学 机械工程系, 制造工程研究所, 摩擦学国家重点实验室, 精密超精密制造装备及控制北京市重点实验室, 北京 100084
Average vector method for determining isocenter of rotated radiotherapy equipment
ZHANG Xiang, FAN Wengang, SHI Shaohua, YE Peiqing, ZHANG Hui
Beijing Key Laboratory of Precision/Ultra-Precision Manufacturing Equipments and Control, State Key Laboratory of Tribology, Institute of Manufacture Engineering, Department of Mechanical Engineering, Tsinghua University, Beijing 100084, China
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摘要 对于旋转放射治疗设备, 其等中心点位置对治疗精度存在重要影响。针对设备负载引起的机械结构变形对等中心误差的影响, 提出了一种确定旋转放疗设备等中心点的平均矢量算法。以等中心点位置为优化变量, 通过限定等中心点与不同位置射线向量的最大距离建立约束条件, 以满足约束条件的等中心点与射线向量的平均距离为目标函数, 得到最优等中心点位置和等中心包络线。 实例分析验证了平均矢量算法的正确性和有效性。平均矢量法与矢量法得出的等中心包络线半径均为0.311 mm, 比节点法降低约15.5%; 平均矢量法给出的等中心点距各射线向量的平均距离为0.206 mm, 比矢量法降低约11.2%, 比节点法降低约28%。
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张翔
樊文刚
史少华
叶佩青
张辉
关键词 放疗设备等中心点射线向量平均矢量法    
Abstract:The isocentric accuracy of rotated radiotherapy equipment significantly influences the treatment accuracy. The average vector method is used to find the optimal isocenter considering the mechanical deformation of the rotated radiotherapy equipment. The maximum distance between the isocenter which is treated as the optimization variable and the ray vectors is considered as a constraint. An objective function is then designed to calculate the average distance between the isocenter that meets the constraint and the ray vectors. Finally, the location of the optimal isocenter and the isocentric envelop are obtained. A test with this method gives the radius of the isocentric envelop as 0.311 mm which is equal to that given by the vector-end-effector method, and about 15.5% less than that given by the point-end-effector method. The results also show that the average distance between the optimal isocenter and the ray vectors is 0.206 mm, about 11.2% less than that by the vector-end-effector method and 28% less than that by the point-end-effector method.
Key wordsradiotherapy equipment    isocenter    ray vector    average vector method
收稿日期: 2014-07-08      出版日期: 2015-09-18
ZTFLH:  TH692.9  
通讯作者: 叶佩青,研究员,E-mail:yepq@tsinghua.edu.cn     E-mail: yepq@tsinghua.edu.cn
引用本文:   
张翔, 樊文刚, 史少华, 叶佩青, 张辉. 确定旋转放疗设备等中心点的平均矢量算法[J]. 清华大学学报(自然科学版), 2015, 55(7): 744-749.
ZHANG Xiang, FAN Wengang, SHI Shaohua, YE Peiqing, ZHANG Hui. Average vector method for determining isocenter of rotated radiotherapy equipment. Journal of Tsinghua University(Science and Technology), 2015, 55(7): 744-749.
链接本文:  
http://jst.tsinghuajournals.com/CN/  或          http://jst.tsinghuajournals.com/CN/Y2015/V55/I7/744
  图1 典型放疗设备简化模型
  图2 平均矢量法原理图
  图3 旋转放疗设备机械结构总变形
  图4 机架不同位置射线源位置偏移
  表1 Matlab仿真参数设置
  图5 旋转放疗设备各位置射线向量分布图
  图6 平均矢量法和节点法的结果比较
  表2 不同方法的最优等中心点结果比较
  图7 平均矢量法和矢量法等中心包络线比较
  图8 平均矢量法和矢量法等中心点到射线向量距离比较
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