Dosimetric comparison of single-arc/partial-arc volumetric modulated arc therapy and intensity-modulated radiotherapy for peripheral and central lung cancer

Aim: The aim of this study is to compare the differences between intensity-modulated radiotherapy (IMRT) and single-arc/partial-arc volumetric modulated arc therapy (SA/PA-VMAT) techniques in locally advanced-stage non-small cell lung cancer (NSCLC). Materials and Methods: Locally advanced 22 patients with NSCLC were evaluated retrospectively. Each patient underwent radiation therapy with either IMRT or SA-VMAT or 2PA-VMAT technique. Homogeneity index, conformity number, and dosimetric parameters were evaluated. Results: Ten peripheral and 12 central lung tumors were evaluated. In the entire patient group, tV5-10-60, total mean lung dose (tMLD), iV5-10-30-50-60, iMLD, and esophagus Dmean and Dmax were lower in IMRT technique, cV5-10-20-30, kMLD, and medulla spinalis Dmax were lower in PA-VMAT technique, whereas iMLD is the highest in the SA-VMAT technique. In peripheral tumors, tV5-10-60, iV5-10-20-30-40-60, iMLD, and esophagus Dmean were lower in IMRT technique and kV5-10 was lower in the 2PA-VMAT technique. In central tumors, tV5-10, tMLD, iV5-60, iMLD, and esophagus Dmean and Dmax were lower in IMRT technique, whereas cV10-20 and medulla spinalis Dmax were lower in 2PA-VMAT, and all contralateral lung doses are high in the SA-VMAT technique (all P < 0.05). Conclusion: IMRT and VMAT techniques have different advantages in locally advanced lung cancer, and the use of those two techniques as a hybrid can provide a single collection of these advantages.