The present invention relates to method for generating planning data or control data for a radiation treatment, comprising the following steps: acquiring segmented data of an object which contains a treatment volume and a non-treatment volume； modelling at least some or all of the volume or surface of the treatment volume as a source of light or rays exhibiting a predefined or constant initial intensity； modelling the non- treatment volume as comprising volumetric elements or voxels which each exhibit an individually assigned feature or attenuation or transparency value (tmin≦t≦tmax) for the light or rays which feature is assigned to the light or ray or which attenuation or transparency maintains or reduces the intensity of the light or ray as it passes through the respective volumetric element or voxel, wherein the feature or attenuation or transparency value is individually assigned to each volumetric element or voxel of the non-treatment volume； defining a map surface which surrounds the treatment volume or the object； calculating an accumulated intensity value for points or areas on the map surface, the accumulated intensity being the sum of the intensities of all the rays which exhibit the predefined or constant initial intensity and are emitted from the volume or surface of the treatment volume and reach a respective point on the map surface preferably by following a straight line, wherein if the ray passes through a non-treatment volume or voxel, the intensity of the respective ray is reduced or attenuated by a factor which is determined by the individual feature or attenuation or transparency value of the respective non-treatment volume or voxel； and generating an intensity distribution on the map surface using the calculated accumulated intensities.
