ABSTRACT
Objective To compare the dosimetric difference among TomoDirect (TD) radiotherapy,Helical Tomotherapy(HT) and volumetric modulated arc therapy(VMAT) in the treatment of upper thoracic esophageal carcinoma.Methods A total of 15 patients with cT2-4 N0-1 M0 upper thoracic esophageal squamous cell carcinoma were enrolled.Three plans were generated using the same dose objective for each patient:TD,HT and VMAT.Dose-volume histogram (DVH),homogeneity index (HI),conformal index (CI),dose at organ at risk (OAR),delivery time and monitor unit (MU) were compared among different plans.Results The D2 and D values in the HT and TD plans were significantly lower than those in the VMAT plans.The D98 value in the TD was similar to that in the HT,but lower than that in the VMAT.The HI of HT was significantly better than those of TD and VMAT (F =81.603,P ＜ 0.05).For the CI,there was no significant difference among the three techniques (P ＞ 0.05).For the V15 of lung,HT was significantly higher than TD (t =-2.626,P ＜0.05) and VMAT (t=3.547,P ＜ 0.05).The V20 of lung in TD was similar to that in HT,but higher than that in VMAT (t =2.824,3.052,P ＜ 0.05).The Dmax of spinal cord showed no significant difference among the three techniques.VMAT had a significantly shorter delivery time and lower MU compared with HT and TD (t =21.617,15.693,10.018,7.802,P ＜ 0.05).Conclusions HT and TD could gain a better planning target volume (PTV) coverage and HI than VMAT in the treatment of upper thoracic esophageal carcinoma.However,VMAT achieved the lowest lung V20,the least Mus and the shortest delivery time.HT achieved a better PTV coverage compared with TD,but TD had a lower lung V15 Mus and shorter delivery time compared with HT.