插值对二维电离室矩阵调强验证Gamma通过率的影响

The Effort to Gamma Pass Rates of Interpolation During the 2D Chamber Array IMRT QA

目的:研究插值对二维电离室矩阵调强验证Gamma通过率的影响。材料和方法:使用IBA二维电离室矩阵对8例调强计划56个射野进行验证。验证中分别使用矩阵固有间隔、线性1 mm间隔插值、三次样条函数1 mm和2 mm间隔插值将测量结果和计划输出进行Gamma分析。比较不同插值方法对3 mm,3%标准Gamma分析的影响。结果:本研究中,电离室矩阵固有间隔(无插值)的Gamma通过率最高,进行样条函数插值后的通过率其次,进行线性插值后的验证通过率最低。结果具有统计学意义(P<0.01)。样条函数插值间隔对Gamma通过率的影响无统计差异。结论:插值后调强验证的Gamma通过率将显著下降,不同插值方法的影响有显著差异。本研究提示,调强验证的Gamma通过率与多种条件相关,放疗单位不宜直接使用文献资料确定本单位的Gamma通过率标准。

Objective：This study is to discuss the effort to Gamma pass rates of interpolation during the 2D chamber array IMRT QA.Methods：An IBA 2D chamber Array was used for IMRT QA,8 cases and 56 fields were included in the project.During the QA,natural measurement,linear interpolation with 1mm,cubic spline interpolation with 1 mm and 2 mm was utilized for Gamma pass rates analysis（3 mm,3%） with plan exports.After that,the pass rate comparison was carried out between the interpolations.Results：The nature measurement had the highest pass rate,the cubic spline was the next,and the linear interpolation had the lowest pass rate.The difference was statistical significance.The space of cubic spline interpolation had no statistical significant influence on Gamma pass rate.Conclusions：After the interpolation,the pass rate decreases obviously,as well as the difference between the interpolation methods.It shows showed the Gamma pass rates in literatures can no be used directly for the tolerance determination.