A method for generating a robust radiation treatment plan for a treatment volume of a subject, said treatment volume being defined using a plurality of voxels, the method comprising, at a processor: - retrieving an initial voxel-specific dose objective defining an initial dose objective dose value for each of a number of voxels in the treatment volume, the initial voxel-specific dose objective corresponding to a desired heterogeneous dose in said treatment volume; - determining at least one adjusted dose objective dose value, for at least one voxel of the number of voxels, comprising performing the following steps a) - c): a) designating one voxel of said number of voxels, for which an adjusted dose objective dose value has not been obtained, as a current voxel for which the initial dose objective dose value is to be adjusted, b) identifying one or more reference voxels in said treatment volume, each of said one or more reference voxels being located within a distance in at least one direction from said designated current voxel, c) adjusting the initial dose objective dose value of said designated current voxel on the basis of the initial dose objective dose values of the one or more reference voxels, whereby an adjusted dose objective dose value of said current voxel is obtained; - determining an adjusted voxel-specific dose objective for said treatment volume at least partly based on said at least one adjusted dose objective dose values; - generating a radiation treatment plan at least partly on the basis of said adjusted voxel-specific dose objective. - retrieving an initial voxel-specific dose objective defining an initial dose objective dose value for each of a number of voxels in the treatment volume, the initial voxel-specific dose objective corresponding to a desired heterogeneous dose in said treatment volume; - determining at least one adjusted dose objective dose value, for at least one voxel of the number of voxels, comprising performing the following steps a) - c): a) designating one voxel of said number of voxels, for which an adjusted dose objective dose value has not been obtained, as a current voxel for which the initial dose objective dose value is to be adjusted, b) identifying one or more reference voxels in said treatment volume, each of said one or more reference voxels being located within a distance in at least one direction from said designated current voxel, c) adjusting the initial dose objective dose value of said designated current voxel on the basis of the initial dose objective dose values of the one or more reference voxels, whereby an adjusted dose objective dose value of said current voxel is obtained; a) designating one voxel of said number of voxels, for which an adjusted dose objective dose value has not been obtained, as a current voxel for which the initial dose objective dose value is to be adjusted, b) identifying one or more reference voxels in said treatment volume, each of said one or more reference voxels being located within a distance in at least one direction from said designated current voxel, c) adjusting the initial dose objective dose value of said designated current voxel on the basis of the initial dose objective dose values of the one or more reference voxels, whereby an adjusted dose objective dose value of said current voxel is obtained; - determining an adjusted voxel-specific dose objective for said treatment volume at least partly based on said at least one adjusted dose objective dose values; - generating a radiation treatment plan at least partly on the basis of said adjusted voxel-specific dose objective.