ABSTRACT
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.