It is an object of the invention to improve treatment planning. This object is achieved by a dose planning system comprising a biopsy map creation module configured for receiving biopsy information for an organ of interest regarding biopsy locations and tissue characteristics of tissue found at the biopsy locations, wherein the biopsy map creation module is further configured for creating a spatially annotated biopsy map for the organ, by linking the spatial information on the biopsy locations to the tissue characteristics of tissue found at the corresponding biopsy locations. The dose planning system further comprises a probability map calculation module configured for creating a tumour probability map by calculating a tumour probability for locations in the organ from which no biopsy was taken by using the tumour and/or tissue characteristics from the biopsy locations and a dose planning module configured for creating a dose plan based on the tumour probability map, wherein planning constraints are such that on average a higher tumour probability results in a higher planned dose and a lower tumour probability results in a lower planned dose.
