Changes in RT fields over time. Figures are 3-dimensional reconstructions of RT fields based on computed tomography imaging. Light green illustrates irradiated field. The true heart position is shown. (A) Mantle and upper abdomen (“spade”) field. Note the large volume of heart and left breast irradiated. (B) Mantle field. (C) IFRT for mediastinal disease without axillary disease. Less breast tissue is treated, although inclusion of the subcarinal nodes encompasses the proximal coronary arteries. (D) INRT for a patient with mediastinal, low neck, and high axillary disease. The patient was also treated with active breath hold to decrease heart dose.