Partial breast irradiation with the 1.5 T MR-Linac: First patient treatment and analysis of electron return and stream effects

摘要

Introduction: External beam partial breast irradiation (PBI) provides equal oncological outcomes compared to whole breast irradiation when applied to patients with low risk tumours. Recently, linacs with an integrated magnetic resonance image-guidance system have become clinically available. Here we report the first-in-human PBI performed at the 1.5 T MR-Linac, with a focus on clinical feasibility and investigation of the air electron stream effect (ESE) and the electron return effect (ERE) in the presence of the 1.5 T magnetic field, which might influence the dose on the chin (out-of-field dose, due to the ESE), the skin and the lung/chest wall interface (in-field dose, ERE).