调强计划验证通过率的影响因素分析

Factors affecting the passing rate of intensity-modulated radiotherapy plans

目的:探讨计划验证通过率的影响因素。方法:选取Pinnacle计划系统设计的68例静态调强计划。将所有射野归到机架0°后利用PTW 729电离室矩阵、固体水模体基于Synergy加速器测量剂量分布,并使用PTW VeriSoft软件分析其与理论值差异。分别以Local和Max方式分析在3 mm/3%标准下的Gamma通过率并比较,然后分析机器跳数、子野数目、子野平均面积、子野面积的变异系数与Local通过率的相关性;回归得到通过率与各影响因素间的线性关系。结果:所有计划Local通过率均低于Max(P<0.01);头颈部通过率与其他部位通过率差异存在显著统计学意义(P<0.01);Local通过率与治疗部位、子野数目、子野面积变异系数存在线性关系。结论:Local通过率显著低于Max;头颈部计划通过率低于其他部位;根据计划的子野数目、机器跳数可以初步判断计划通过率;治疗部位、子野数目、子野面积的变异系数是影响Local通过率的主要因素,多重线性回归方程能对计划设计及选择起一定的指导作用。

Objective To investigate the factors which affects the passing rate of intensity-modulated radiotherapy(IMRT)plans.Methods Atotal of 68 static IMRT plans designed by Pinnacle treatment planning systems were selected.After all radiation fields were normalized to gantry angle 0°,the dose distributions were measured with PTW729 chamber array and solid water phantom based on Synergy accelerator.Then PTWVeriSoft software was used to compare the differences between measured results and computed values.Using 3 mm/3%criteria,the Gamma passing rates of Local and Max were analyzed and compared.The correlations between the passing rate of Local and various factors,such as monitor unit,the number of segments,the mean area of segments and the coefficient of variation of segments area,were analyzed.Regression analysis was used to obtain the linear relationship between the passing rate and the affecting factors.Results The passing rates of Local were lower than those of Max for all plans(P<0.01).The passing rates of head and neck plans were significantly different from other sites,with statistical significances(P<0.01).The passing rates of Local had linear relationships with the treatment sites,the number of segments and the coefficient of variation of segments area.Conclusion The passing rate of Local is significantly lower than that of Max.Compared with plans for other sits,head and neck plan has a lower passing rate.The passing rates of Local can be preliminary estimated by monitor unit and the number of segment.Treatment sites,the number of segments and the coefficient of variation of segments area are the main factors that affect the passing rates of Local.Multiple linear regression equations can provide some guidance for the design and selection of optimal plans.