1. A method for determining a range of particle radiation, the method comprising: defining a target volume to be irradiated, the target volume characterized by a plurality of voxels; determining, without exposing the target volume to particle radiation, radiation-attenuating properties that are associated with individual voxels of the plurality of voxels by performing a medical imaging procedure; deriving a first range datum of a first voxel and range datums of two adjacent voxels from the radiation-attenuating properties; and changing the first range datum of the first voxel when the range datum of the first voxel differs from the range datums of the two adjacent voxels.