A dose planning study for cardiac and lung dose sparing techniques in left breast cancer radiotherapy: Can free breathing helical tomotherapy be considered as an alternative for deep inspiration breath hold?

•Helical Tomotherapy in free breathing; an alternative for heart and ipsilateral lung dose sparing for patient who cannot comply with deep inspiration breath hold.•Significant contralateral dose reduction with 3D conformal radiotherapy in deep inspiration breath hold compared to Helical Tomotherapy in left breast radiotherapy.•Helical Tomotherapy; effective for toxicity management for left breast cancer patients with targets with internal mammary and regional lymph nodes.