子宫内膜癌术后放疗旋转调强与静态调强的剂量学比较

Dosimetric comparison between volume rotational intensity modulated radiation therapy and intensity modulated radiation therapy for endometrial carcinoma

目的:对容积旋转调强放疗(VMAT)和静态固定野调强放疗(IMRT)在子宫内膜癌术后放疗中的应用进行剂量学比较。方法:选取30例子宫内膜癌术后患者,使用Varian Eclipse10.0计划系统,对每例患者设计VMAT计划和IMRT计划,处方量为50Gy(2Gy/次×25次)。比较2种治疗下靶区内剂量分布的适形性、均匀性及正常组织的受照剂量。结果:计划平均适形性指数VMAT为0.86,IMRT为0.83,平均均匀性指数均为0.07;与IMRT计划相比,VMAT计划的脊髓Dmax、股骨头D5%、膀胱D50%平均受照剂量分别下降了3.8Gy、3.5Gy和3.0Gy;VMAT计划的MU均值为643,IMRT计划为876,两者存在显著性差异(P<0.05)。结论:VMAT计划可以达到与IMRT计划相近的靶区剂量分布,在脊髓、股骨头、膀胱等正常组织的保护上更好。VMAT可安全高效地应用于子宫内膜癌术后的放射治疗中。

Objective：To compare dosimetric differences of postoperative radiotherapy for endometrial cancer using volume rotational intensity modulated radiation therapy （VMAT）and intensity modulated radiation therapy （IMRT）.Metbods：Thirty postoperative endometrial cancer patients were selected for radiotherapy with a dose of 50Gy dividing into 25 fractions at planning target volume（PTV）by Eclipsel0.0.Each case was planned with VMAT and IMRT techniques.Target conformability index,homogeneity index,dose-volume histogram data,moni- tor units and time required for each fraction of treatment were compared between these two techniques.Re- suits：The mean conformability indexes of the two groups were 0.86 in VMAT and 0.83 in IMRT,and the mean homogeneity indexes in both groups were 0.07.The average dose of VMAT in the Dmax of spinal cord, D5% of femoral head and D50% of bladder was 3.8 Gy,3.5 Gy and 3.0 Gy,respectively;and less than those of IMRT group;D10%,D40%,Dmax of small intestine and D10% of colon were not significantly different be- tween the two groups.The mean MU of the VMAT was 643 and while of IMRT was 876（P〈0.01）,with signif- icant difference.Conclusion：VMAT achieves similar target dose distribution as that of IMRT,and with better protection of organs at risk such as spinal cord,femoral head and bladder.Compared with IMRT,VMAT as a highly effective treatment may significantly reduces the patients＂ discomfort and uncertain factors in the treat- ment process with less MU.