Robustness analysis of surface-guided DIBH left breast radiotherapy: personalized dosimetric effect of real intrafractional motion within the beam gating thresholds.

The DIBH technique proved to be robust against residual intrafractional isocenter shifts allowed by the selected SGRT beam-hold thresholds. Small-volume OARs located near high dose gradients showed significant marginal deteriorations in the perturbed plans with the 3DCRT technique only. Global plan quality was mainly influenced by patient anatomy and treatment beam geometry rather than the technique adopted.