TQA数据趋势与TomoTherapy输出稳定性的联系

目的:探讨TomoTherapy QualityAssurance（TQA）数据趋势与螺旋断层放疗（Helical Tomotherapy，HT）系统输出的 联系。方法:回顾性分析了本院HT系统近3年内TQA各个模块的参数和数据趋势，探讨其与HT系统的静态输出剂量和 输出能量（D20/D10）变化的相关性。结果:楔形阶梯静态模块的z轴偏移参数与HT的静态输出剂量的相关性最强（r=0.883, P<0.01）。基本剂量测定模块的出口检测器平整度值对能量变化最敏感（r=0.902），其次是楔形阶梯静态模块的能量差异 （r=0.897）和楔形阶梯螺旋模块的能量差异（r=0.852），灵敏度分别为2.3×10-4、3.1×10-4和5.7×10-4。结论:TQA有助于用户 追踪HT输出剂量和能量变化，及早进行必要的机器维护或剂量校准。

Correlation between TQA data trends and output of helical tomotherapy

Objective To discuss the relationship between tomotherapy quality assurance (TQA) data trends and output of helical tomotherapy (HT). Methods The correlations between static output and output energy variation (D20/D10) were determined based on the retrospective analysis on the parameters and data trends of each module of TQA of HT in recent 3 years. Results The offset parameter of z axis in step-wedge static module had the best correlation with the static output of HT (r=0.883, P<0.01). The exit detector flatness in basic dosimetry module was the most sensitive to energy changes (r=0.902), followed by energy differences in step-wedge static module (r=0.897) and energy differences in step-wedge helical module (r =0.852), and their sensitivities were 2.3×10-4, 3.1×10-4 and 5.7×10-4, respectively. Conclusion TQA can help user to monitor the changes in the output and energy of HT, thereby carrying out necessary maintenance and dosimetric validation earlier.