多丝电离室系统对加速器剂量学影响的研究

Effect of DAVID system on dosimetry of linear accelerator

目的:分析多丝电离室系统对ELEKTA Synergy加速器射野剂量学的影响,为进一步开展临床应用提供支持。方法:应用三维水箱分别测量加速器有无多丝电离室系统时不同射野下的百分深度剂量(percentage depth dose,PDD)及不同射野、不同深度的枪靶(G-T)方向、左右(L-R)方向的离轴比(off-axis ratio,OAR),并测量加速器有无多丝电离室系统时的吸收剂量。结果:各射野PDD、OAR不受多丝电离室系统影响;吸收剂量受其影响,使射线衰减达到7%。结论:在使用多丝电离室系统时不需修改计划系统的射野参数,但需要依据射线传输因子对患者计划进行剂量修正。

Objective To explore the effect of DAVID system on the beam dosimetry of ELEKTA Synergy accelerator.Three-dimensional water phantom system was used to measure the values of percentage depth dose （PDD） indifferent fields, gun-trarget （G-T） in different fields and depths as well off-axis ratio （OAR） at left-right （L-R） direction whenthe accelerator was equipped with DAVID system or not. DAVID system had no effects on PDD and OAR, whileinfluenced the absorbed dose so that the ray was attenuated by 7%. The field parameters have not to be modifiedfor the planning system when using DAVID system, but the dose correction has to be performed according to ray transmissionfactors.