Dosimetric comparison of 3D-conformal radiotherapy, volumetric modulated arc therapy, and h-VMAT in left breast radiotherapy under free-breathing and breath-hold conditions

This study investigates the role of the h-VMAT (a hybrid of 3DCRT and VMAT) technique in the Deep Inspirational Breath-Hold (DIBH) method for left-breast irradiation by comparing dosimetric parameters of 3DCRT, VMAT, and h-VMAT plans in free breathing and breath-hold conditions. The study enrolled fourteen left breast cancer patients with nodal involvement. Five sets of plans, namely, 3DCRT, VMAT, and three different dose ratios of h-VMAT, were created in both the DIBH and Free-Breathing (FB) data sets. All plans had similar planning criteria and were compared using Dose-Volume parameters of the target and critical organs. Both h-VMAT and VMAT achieved acceptable PTV parameters compared to 3DCRT. A significant reduction in heart mean dose was observed in the h-VMAT80/20 (p < 0.001) under both DIBH and FB methods and was found to be minimal compared to 3DCRT and VMAT. Similarly, Left Anterior Descending Artery (LAD) dose was also reduced in hybrid. Additionally, the left lung volume receiving 20 Gy and 30 Gy were less in hybrid. We conclude that h-VMAT, along with DIBH, is successful in achieving the best trade-off between heart exposed to high and low doses of radiation compared to 3DCRT and VMAT, respectively, without compromising target coverage for left breast radiotherapy.