Systems and methods of controlling the leaves of an aperture in radiation treatment are disclosed. In some embodiments, these systems and methods allow the delivery of different radiation fluences to different parts of a treatment volume in a single rotation of the aperture around the treatment volume. In some embodiments, different radiation fluences are achieved by radiating different parts of the treatment volume from opposing positions of the aperture around the treatment volume. In some embodiments, different radiation fluences are achieved by assigning different leaf pairs to radiate different parts of the treatment volume.