宫颈癌术后IG-VMAT剂量学及不良反应研究

目的 比较宫颈癌术后图像引导VMAT (IG-VMAT)与固定野IMRT (FF-IMRT)的剂量学差异和不良反应。方法 选取2013年间两家医院收治70例Ⅰ _b-Ⅱ _a期宫颈癌术后具有高危因素患者,均分为FF-IMRT与IGRT-VMAT组,比较两组患者靶区剂量和不良反应差异。结果 IG-VMAT组分次间x、y、z轴向摆位误差分别为(0.25±0.14)、(0.26±0.16)、(0.24±0.18) cm, 分次内的分别为(0.1±0.09)、(0.12±0.09)、(0.11±0.09) cm;x、y、z轴向外扩边界分别为0.75、0.84、0.78 cm。在相同处方剂量下IG-VMAT组适形度、治疗时间、机器跳数明显优于FF-IMRT (P=0.000)。IG-VMAT组膀胱、直肠和小肠D_mean、高剂量受照体积均低于FF-IMRT组(P=0.000)。IG-VMAT组急慢性胃肠道、泌尿系统及血液系统不良反应发生率明显降低(P<0.05)。结论 IG-VMAT不仅能在线实时调整摆位误差,且缩短治疗时间、降低OAR受量、减轻急慢性不良反应,适用于术后小肠位置下移者。

Comparison of dosimetry and toxicities between postoperative fixed-field intensity-modulated radiotherapy and image-guided radiation therapy/volumetric modulated arc therapy for cervical cancer

Objective To compare the dosimetry and toxicities between postoperative fixed-field intensity-modulated radiotherapy (FF-IMRT) and image-guided radiation therapy/volumetric modulated arc therapy (IGRT-VMAT) for cervical cancer.Methods A total of seventy patients with stage I b-Ⅱa postoperative cervical cancer who had high risk factors,were divided into FF-IMRT (FF-IMRT group,n =35)and IGRT-VMAT (IGRT-VMAT group,n =35),to compare the difference of target dose and adverse reaction between the two groups.Results In the IGRT-VMAT group,the interfractional setup errors in the x,y,and z axes were (0.25±0.14) cm,(0.26±0.16) cm,and (0.24±0.18) cm,respectively;the intrafractional setup errors in the x,y,and z axes were (0.1±0.09) cm,(0.12±0.09) cm,and (0.11±0.09) cm,respectively;the margins in the x,y,and z axes were 0.75 cm,0.84 cm,and 0.78 cm,respectively.Under the same dosimetric conditions,the IGRT-VMAT group was superior to the FF-IMRT group in terms of conformity index,treatment time,and number of monitor units (P=0.000).The Dmean and volume receiving high-dose irradiation for the bladder,rectum,and small intestine were significantly lower in the IGRT-VMAT group than in the FF-IMRT group (P=0.000).Compared with the FF-IMRT group,the IGRT-VMAT group had a significantly reduced incidence of acute and chronic gastrointestinal,urinary,and hematologic toxicities (P＜ 0.05).Conclusions IGRT-VMAT can correct setup error online,shorten the treatment time,reduce the dose to organs at risk,and alleviate acute and chronic toxicities,and is especially suitable for patients with postoperative small bowel position changes.