Figure 1.

(A) A magnetic resonance (MR)–based, adaptive plan for fraction 1 (fx1) met all organ-at-risk (OAR) constraints based on daily setup anatomy from fx1. (B) Application of the fx1 plan to the fx2 MR image of a patient with an upper paratracheal metastasis (blue colorwash) abutting the esophagus (pink colorwash) resulted in violation of hard esophageal and trachea (green colorwash) constraints. (C) Daily adaptive planning for fx2 achieved OAR violation reversal while preserving target volume coverage, as determined by dose-volume histogram comparison (D). (A color version of this figure is available at https://dx.doi.org/10.1016/j.adro.2018.10.003.)