A computer-implemented method for planning a trajectory through an anatomical body part, the trajectory being usable for a medical procedure and the method comprising executing, on at least one processor of at least one computer, steps of: a) acquiring, at a processor, patient image data describing a medical image of a patient anatomical body part being the anatomical body part in a patient's body; b) acquiring, at a processor, atlas trajectory data describing a model anatomical body part being a model of the patient anatomical body part, and describing the position of at least one predetermined trajectory through the model anatomical body part; c) acquiring, at a processor, critical structure data describing the position of at least one critical structure in the model anatomical body part or in the patient anatomical body part; d) determining, by a processor and based on the patient image data and the atlas trajectory data and the critical structure data, mapping data describing a mapping of the model anatomical body part, of the position of the at least one predetermined trajectory and of the position of the at least one critical structure onto the medical image of the patient anatomical body part; e) determining, by a processor and based on the mapping data and the atlas trajectory data and the patient image data, analysis region data describing an analysis region in the patient image data, the analysis region having a position in the patient anatomical body part fulfilling a predetermined spatial condition relative to the position of the mapped predetermined trajectory; f) determining, by a processor and based on the patient image data and the atlas trajectory data and the analysis region data and the critical structure data, straight trajectory data describing a straight line trajectory through the patient anatomical body part within the analysis region having a position fulfilling a predetermined spatial condition relative to the position of at least one critical structure in the patient anatomical body part. a) acquiring, at a processor, patient image data describing a medical image of a patient anatomical body part being the anatomical body part in a patient's body; b) acquiring, at a processor, atlas trajectory data describing a model anatomical body part being a model of the patient anatomical body part, and describing the position of at least one predetermined trajectory through the model anatomical body part; c) acquiring, at a processor, critical structure data describing the position of at least one critical structure in the model anatomical body part or in the patient anatomical body part; d) determining, by a processor and based on the patient image data and the atlas trajectory data and the critical structure data, mapping data describing a mapping of the model anatomical body part, of the position of the at least one predetermined trajectory and of the position of the at least one critical structure onto the medical image of the patient anatomical body part; e) determining, by a processor and based on the mapping data and the atlas trajectory data and the patient image data, analysis region data describing an analysis region in the patient image data, the analysis region having a position in the patient anatomical body part fulfilling a predetermined spatial condition relative to the position of the mapped predetermined trajectory; f) determining, by a processor and based on the patient image data and the atlas trajectory data and the analysis region data and the critical structure data, straight trajectory data describing a straight line trajectory through the patient anatomical body part within the analysis region having a position fulfilling a predetermined spatial condition relative to the position of at least one critical structure in the patient anatomical body part.