Voluntary versus ABC breath-hold in the context of VMAT for breast and locoregional lymph node radiotherapy including the internal mammary chain.

Background: Deep-inspiration breath-hold (DIBH) reduces radiation dose to the heart in patients undergoing locoregional breast radiotherapy. In the context of tangential irradiation of the breast/ chest wall, a voluntary breath hold (vDIBH) technique has been shown to be as reproducible as a machine-assisted breath hold technique using the active breathing co-ordinator (ABC™, Elekta, Crawley, UK, ABC_DIBH). This study compares set-up reproducibility for vDIBH versus ABC_DIBH in patients undergoing volumetric-modulated arc radiotherapy (VMAT) for breast cancer, both with and without wax bolus.