This study aimed to investigate 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). 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, organ at risk sparing, treatment parameters including monitor units and treatment time (TT) were evaluated. Wilcoxon signed-rank test was used to check for significant differences (p < 0.05) between datasets. VMAT plans (pVMAT and fVMAT) significantly reduced total lung volume treated above 20 Gy (V20), 25 Gy (V25), 30 Gy (V30), 35 Gy (V35), 40 Gy (V40), and without increasing the value of V10, V13, and V15. For V5 of total lung value, pVMAT was similar to aIMRT, and it was better than fVMAT. Both pVMAT and fVMAT improved the target dose coverage and significantly decreased maximum dose for the spinal cord, monitor unit, and TT. No significant difference was observed with respect to V10 and V15 of body. VMAT AP plan was a good option for treating upper thoracic
esophageal cancer with T3N0M0, especially partial
arc VMAT AP plan. It had the potential to effectively reduce lung dose in a shorter TT and with superior target coverage and dose homogeneity.