Purpose: To investigate the impact of the single-isocentre technique on the volumetric dose of lung and heart for adjuvant radiation in breast cancer with regional nodal. Methods and materials: Thirty patients treated for breast cancer with supraclavicular fossa irradiation; two techniques of treatment TMT (Traditional Matching Technique) and MIT (Mono-Isocentric Technique) are compared, TMT (tangents in SAD and supraclavicular (SCL) in SSD: Source Skin Distance) and MIT (the all fields in SAD: Source Axe Distance) (Chart 1). Techniques were compared according to dose volume histograms (DVHs) analysis in terms of PTV homogeneity and as OARs (Organs at Risk) dose and volume parameters. Results: The dose distribution in PTV is similar in the both techniques TMT and MIT but with hot spots in the junction of the three fields for the TMT (average 120% for TMT and 110% for MIT). The analysis of DVHs shows a decrease in the mean OARs. Lung and heart dose is improved using the MIT and with significant difference in the V20 and V30 for the lung and in the V10 and V40 for the heart. Conclusions: The results of our study demonstrated that the target volumes were sufficiently irradiated with the MIT and the lung and heart volumes irradiated were small. Furthermore, it should not be over or under dose in the supraclavicular and tangential junction.