1. A method for determining the position of a nerve fiber based on diffusion image-based tracking of nerve fibers, the method executing on a processor of a computer, and comprising: a) acquiring, at the processor, medical image data describing a medical image of an anatomical body part of a patient's body comprising the nerve fibers, the medical image generated by applying a diffusion-based medical imaging method to the anatomical body part; b) acquiring, at the processor, tracking initiation data describing a minimum fractional anisotropy and a minimum length of nerve fibers to be selected for tracking; c) acquiring, at the processor, first recording mode data describing whether a recording mode for recording the result of the tracking is enabled or disabled; d) acquiring, at the processor, initial position data describing an initial position of a virtual tool in the medical image; e) acquiring, at the processor, atlas data describing a model of the anatomical body part of the patient's body comprising the nerve fibers; f) determining, by the processor, seed point data, the seed point data based on the medical image data, tracking initiation data, and the initial position data, and wherein the seed point data describes a set of seed points serving as starting points for the tracking; g) initiating, by the processor, and based on the medical image data and the seed point data, the tracking, and writing the tracked nerve fibers into a tracking result data set; h) determining, by the processor and based on the tracking result data set, whether a nerve fiber has been tracked, and if it is determined that no fiber has been tracked, h1) acquiring, at the processor, and evaluating, by the processor, continuation data indicating whether the method shall continue, and if the continuation data indicates that the method shall not continue, ending, by the processor, the method, otherwise at least one of: changing, by the processor, the tracking initiation data and acquiring the changed tracking data, repeating execution of the method starting from step g) and using the changed tracking initiation data as an input for a repetition of step g); and changing, by the processor, the initial position data and acquiring the changed initial position data, repeating execution of the method starting from step f) and using the changed initial position data as an input for a repetition of step f); if it is determined that a fiber has been tracked, h2) determining, by the processor, tracked fiber visualization data describing an image rendering of the tracked nerve fiber described by the tracking result data; i) determining, by the processor and based on the first recording mode data, whether the recording mode is enabled or disabled, and if it is determined that the recording mode is not enabled, continuing, by the processor, execution of the method with step h1); if it is determined that the recording mode is enabled, acquiring, at the processor, and evaluating, by the processor, recorded fiber data indicating whether a set of already at least one recorded nerve fiber exists to which the tracked nerve fiber can be added, and if the evaluation results in that the set of at least one already recorded nerve fiber exists, i1) adding, by the processor, the tracked nerve fiber to the set of at least one already recorded nerve fiber, determining, by the processor, recorded fiber visualization data describing an image rendering of the set of the at least one already recorded nerve fiber after the tracked nerve fiber has been added, and continuing, by the processor, execution of the method with step h1), wherein the acquiring the continuation data of step h1) includes determining, by the processor, and based on the atlas data, and the at least one of the tracking result data and the recorded fiber visualization data, whether the tracked fiber, or the set of at least one already recorded fiber after the tracked fiber has been added, corresponds at least within a predetermined limit to a nerve fiber comprised in the model; if it is determined that the set of at least one already recorded nerve fiber does not exist, i2) creating, by the processor, a data structure for recording a set of at least one tracked nerve fiber serving as the set of at least one already recorded nerve fiber, and continuing, by the processor, execution of the method with step i1).