Analysis of the movement of calcified lymph nodes during breathing

Mediastinal lymph nodes move during breathing, and this needs to be accounted for when the internal margin component of the PTV is defined. The amplitude of this movement is anisotropic and seems to be less than that reported for primary lung tumors. This should permit a modest reduction in the margin allowed for breathing movement around involved mediastinal nodes, particularly in the mediolateral and dorsoventral planes.