Disclosed is a computer-implemented medical data processing method for determining a dose distribution for use in a medical procedure involving irradiation of an anatomical structure of a patients body with ionising radiation. A processor acquires medical image data describing a medical image of the anatomical structure. The processor acquires dose distribution data describing an irradiation dose distribution spatially defined in the reference system of the medical image of the anatomical structure. Prioritization data is determined that describes, for each image unit of the medical image describing non-target tissue, a priority of that image unit for consideration during an optimization of the irradiation dose distribution described by the dose distribution data. Based on the dose distribution data and the prioritization data, changed dose distribution data is determined that describes a changed irradiation dose distribution spatially defined in the reference system of the medical image of the anatomical structure.
