Disclosed is a method for determining an irradiation trajectory for the movement of a treatment device for irradiating an anatomical structure with ionising treatment radiation, the method comprising steps ofacquiring medical image data describing a medical image of the anatomical structure；determining, based on the medical image data, image concavity data；acquiring predetermined concavity data；determining, based on the image concavity data and the predetermined concavity data, partition data；determining, based on the medical image data, partition boundary data； anddetermining, based on the partition boundary data, irradiation trajectory data.
