A radiation system includes a radiation source providing therapeutic radiation, a first gantry supporting a second gantry carrying the radiation source. The first gantry is rotatable about a first axis passing through an isocenter, thereby allowing the radiation source to aim therapeutic radiation at a target volume from a plurality of locations in a first plane. The second gantry carrying the radiation source is rotatable about a second axis passing through the isocenter non-parallel with the first axis, thereby allowing the radiation source to aim therapeutic radiation at the target volume from a plurality of locations in a second plane non-coplanar with the first plane.
