A system (10) for visualizing and modifying the thickness of a compensator (26) for radiation therapy in the context of a desired target and dose coverage thereof includes planar slice image generation module (40), a visualization unit (42) and an adjustment module (44). The planar slice image generation module (40) generates a series of planar slice images (24) from a patient image data set (14) disposed with one axis parallel to a radiation beam and one axis perpendicular to the radiation beam (22). The visualization unit (42) graphically depicts a compensator thickness profile (26), a target of interest (28), and/or a dose representation on at least one of the series of planar slice images (24) all in the same plane lying in a beams longitudinal direction. The adjustment module (44) receives user input of an adjustment of at least one compensator thickness value via a manipulation of the graphical depiction thereof.
