Chen H, et al. - This article was written with the objective to research the dosimetric differences and lung sparing between volumetric-modulated arc therapy (VMAT) and intensity-modulated radiation therapy (IMRT) in the treatment of upper thoracic esophageal cancer with T3N0M0 for preoperative radiotherapy by auto-planning (AP). According to the outcome obtained, VMAT AP plan was a good alternative for treating upper thoracic esophageal cancer with T3N0M0, particularly partial arc VMAT AP plan. It could successfully decrease lung dose in a shorter treatment time (TT) and with superior target coverage and dose homogeneity.

• Sixteen patient cases diagnosed with upper thoracic esophageal cancer T3N0M0 for preoperative radiotherapy were retrospectively studied, and 3 plans were generated for each patient: full arc VMAT AP plan with double arcs, partial arc VMAT AP plan with 6 partial arcs, and conventional IMRT AP plan.
• A simultaneous integrated boost with 2 levels was planned in all patients.
• Target coverage, the organ at risk sparing, treatment parameters including monitor units and treatment time (TT) were evaluated.
• Wilcoxon signed-rank test was utilized to check for significant differences (p<0.05) between datasets.
• VMAT plans (pVMAT and fVMAT) significantly decreased total lung volume treated above 20Gy (V₂₀), 25Gy (V₂₅), 30Gy (V₃₀), 35Gy (V₃₅), 40Gy (V₄₀), and without increasing the value of V₁₀, V₁₃, and V₁₅.
• For V5of total lung value, pVMAT was similar to aIMRT, and it was superior to fVMAT.
• Both pVMAT and fVMAT improved the target dose coverage and significantly reduced maximum dose for the spinal cord, monitor unit, and TT.
• There was no significant difference with respect to V₁₀ and V₁₅ of the body.