A computer-implemented medical data processing method for determining the pose of an anatomical body part of a patient's body for planning radiation treatment, the method comprising the following steps: a) three-dimensional reference image data is acquired which describes a reference image of both a reference pose of an internal anatomical reference structure of the anatomical body part and a reference pose of an anatomical reference surface of the anatomical body part; b) surface tracking data is acquired which describes a tracking image of a current pose of the anatomical reference surface of the anatomical body part; c) a reference surface pose similarity measure is determined by comparing the reference pose of the anatomical reference surface and the current pose of the anatomical reference surface; d) reconstructed image data which describes a reconstructed two-dimensional reference image of the internal anatomical reference structure is generated from the reference image data; e) current reference structure image data is acquired which describes a current two-dimensional image of a current pose of the internal anatomical reference structure; f) a reference structure pose similarity measure is determined by comparing the reference pose of the internal anatomical reference structure and the current pose of the internal anatomical reference structure; g) an optimized pose of the anatomical body part is determined which is associated with optimal values of the reference surface pose similarity measure and the reference structure pose similarity measure, characterized in that the surface tracking data has been generated by applying a structured light tracking modality or three-dimensional thermal tracking modality or a combination of structured light and thermal tracking modality or surface scan laser tracking modality or visible digital photography tracking modality or a time-of-flight tracking modality to the anatomical body part. a) three-dimensional reference image data is acquired which describes a reference image of both a reference pose of an internal anatomical reference structure of the anatomical body part and a reference pose of an anatomical reference surface of the anatomical body part; b) surface tracking data is acquired which describes a tracking image of a current pose of the anatomical reference surface of the anatomical body part; c) a reference surface pose similarity measure is determined by comparing the reference pose of the anatomical reference surface and the current pose of the anatomical reference surface; d) reconstructed image data which describes a reconstructed two-dimensional reference image of the internal anatomical reference structure is generated from the reference image data; e) current reference structure image data is acquired which describes a current two-dimensional image of a current pose of the internal anatomical reference structure; f) a reference structure pose similarity measure is determined by comparing the reference pose of the internal anatomical reference structure and the current pose of the internal anatomical reference structure; g) an optimized pose of the anatomical body part is determined which is associated with optimal values of the reference surface pose similarity measure and the reference structure pose similarity measure, characterized in that the surface tracking data has been generated by applying a structured light tracking modality or three-dimensional thermal tracking modality or a combination of structured light and thermal tracking modality or surface scan laser tracking modality or visible digital photography tracking modality or a time-of-flight tracking modality to the anatomical body part.