放疗床多目标协调机构参数优化研究

Multi target coordinated mechanism parameter optimization method for radiotherapy bed

随着精确放疗技术在肿瘤治疗中的广泛应用,放疗床的研发也受到人们越来越多的关注.为了达到使放疗床的工作空间和结构尺寸能够满足实际使用要求的目的,提出针对6-HTRT并联构型放疗床的一种多目标协调的机构参数优化方法.研究过程中首先对放疗床进行了运动学分析,结合运动学逆解约束条件,对双端虎克铰形式的并联放疗床进行工作空间的精确分析,并得到工作空间随各结构参数的变化规律,为放疗床的参数优化提供依据.其次,针对提高虎克铰强度及刚度问题,提出了一种虎克铰初始安装角度优化方法.之后考虑工作空间、放疗床受力、雅可比矩阵条件数,同时构建关于条件数全域均值、条件数波动情况的目标函数,对放疗床进行参数的具体优化.最终得到了放疗床各结构参数,经验证使得放疗床的雅可比矩阵条件数在工作空间内较小且分布均匀.由上述可知,所研究的放疗床多目标协调机构参数优化方法在一定范围内可以减小雅克比矩阵条件数,使经过参数优化后的放疗床得到合理的工作空间和结构尺寸,满足实际使用的要求.

With the wide application of precise radiotherapy techniques in the treatment of tumor,the research of radiotherapy bed is receiving more and more attention.To achieve the aim that the workspace and the dimensions of the structure of the radiotherapy bed can meet the requirement in actual use,the multi target coordinated mechanism parameter optimization method for radiotherapy bed was introduced.In the research,the kinematics analysis of the radiotherapy bed was firstly carried out,the precise analysis of the workspace was taken on the double universal joints parallel radiotherapy bed,combining with the other inverse solution constraints.Then the influence of workspace by changing the rule of geometric parameters was obtained,which could provide the basis for the parameter optimization of the radiotherapy bed.For the problem of improving the strength and rigidity of the Hooke joint,a method of optimizing the initial mounting angle of the Hooke joint was proposed.Considering the workspace,the forces on it and the Jacobian matrix condition number,the objective function of the universe average of condition number and the fluctuation of condition number was constructed at the same time,the specific optimization of radiotherapy bed parameters was carried out.Finally,the parameters of the radiotherapy bed were obtained with the smaller condition number with uniform distribution of the Jacobian matrix in the whole workspace.According to the above,the multi target coordinated parameters optimiza-tion method for radiotherapy bed can reduce the Jacobian matrix condition number within limits.With the method,the radiotherapy bed can get the reasonable workspace and structure after the parameters are optimized,and can meet the requirement of actual use.