Volumetric modulated arc therapy and breath-hold in image-guided locoregional left-sided breast irradiation

Abstract

PurposeTo investigate the effects of using volumetric modulated arc therapy (VMAT) and/or voluntary moderate deep inspiration breath-hold (vmDIBH) in the radiation therapy (RT) of left-sided breast cancer including the regional lymph nodes. Materials and methodsFor 13 patients, four treatment combinations were compared; 3D-conformal RT (i.e., forward IMRT) in free-breathing 3D-CRT(FB), 3D-CRT(vmDIBH), 2 partial arcs VMAT(FB), and VMAT(vmDIBH). Prescribed dose was 42.56Gy in 16 fractions. For 10 additional patients, 3D-CRT and VMAT in vmDIBH only were also compared. ResultsDose conformity, PTV coverage, ipsilateral and total lung doses were significantly better for VMAT plans compared to 3D-CRT. Mean heart dose (Dmean,heart) reduction in 3D-CRT(vmDIBH) was between 0.9 and 8.6Gy, depending on initial Dmean,heart (in 3D-CRT(FB) plans). VMAT(vmDIBH) reduced the Dmean,heart further when Dmean,heart was still >3.2Gy in 3D-CRT(vmDIBH). Mean contralateral breast dose was higher for VMAT plans (2.7Gy) compared to 3DCRT plans (0.7Gy). ConclusionsVMAT and 3D-CRT(vmDIBH) significantly reduced heart dose for patients treated with locoregional RT of left-sided breast cancer. When Dmean,heart exceeded 3.2Gy in 3D-CRT(vmDIBH) plans, VMAT(vmDIBH) resulted in a cumulative heart dose reduction. VMAT also provided better target coverage and reduced ipsilateral lung dose, at the expense of a small increase in the dose to the contralateral breast.