一种新型热塑膜定位器在放疗体位固定中的摆位精度和剂量精度

Positioning accuracy and dose accuracy in radiotherapy using a novel positioner for thermoplastic immobilization

目的:研究放疗热塑膜固定中有无热塑膜定位器的摆位时间差异、体位精度差异和剂量精度差异。方法:随机选取需应用热塑膜固定的放疗患者3例,每个病人有一半的治疗次数不使用定位器,有一半的治疗次数使用定位器。记录摆位时间、MVCT扫描匹配后的三维方向摆位误差、三维空间矢量位移误差和剂量精度误差,应用2.5∑+0.7σ来计算计划靶区(PTV)外扩边界。结果:无热塑膜定位器组和有热塑膜定位器组的误差在X轴方向分别为6.90(2.85,12.10)mm和2.60(1.45,8.10)mm(P=0.007),Y轴方向分别为9.30(4.05,16.15)mm和5.00(2.60,9.50)mm(P=0.002),Z轴方向分别为3.40(2.05,4.10)mm和1.90(1.30,3.65)mm(P=0.017)。无热塑膜定位器组和有热塑膜定位器组在X、Y、Z轴的PTV外扩边界分别为9.15、14.62、2.15 mm和6.50、7.04、2.97 mm。结论:热塑膜定位器在热塑膜固定中的应用能够减少放疗患者三维空间摆位误差,并且减少PTV外扩边界。

Objective To investigate the differences in positioning time,positional accuracy,and dose accuracy between the use and non-use of thermoplastic film positioners in radiotherapy immobilization.Methods Three patients requiring thermoplastic immobilization for radiotherapy were enrolled,with half of the treatments using a thermoplastic film positioner and the other half without.The positioning time,three-dimensional directional positioning errors after MVCT scanning matching,three-dimensional spatial vector displacement errors,and dose accuracy errors were recorded.The PTV margin was calculated using 2.5Σ+0.7σ.Results The errors of no-positioner group and positioner group were 6.90(2.85,12.10)mm versus 2.60(1.45,8.10)mm in the X-axis direction(P=0.007),9.30(4.05,16.15)mm versus 5.00(2.60,9.50)mm in the Yaxis direction(P=0.002),3.40(2.05,4.10)mm versus 1.90(1.30,3.65)mm in the Z-axis direction(P=0.017),respectively.The PTV margins in the X,Y and Z axes were 9.15,14.62,2.15 mm in no-positioner group,and 6.50,7.04,2.97 mm in positioner group,respectively.Conclusion The application of positioners in thermoplastic immobilization can reduce the three-dimensional spatial positioning errors and minimize PTV margin.