The aim of this paper is an introduction to virtual human phantoms, so-called voxel models that are used for radiation protection purposes. Their application in mathematical simulations for organ dosimetry will be shortly discussed as well as the process of their creation, i.e. segmentation. Katja, the virtual model of a woman in the 24th week of pregnancy, is introduced as a new member of the GSF voxel model family. This model was combined from two datasets – one of the mother and a separate one of the foetus. Only the latter dataset had to be newly created; for the mother, an already existing human model was used. This model was modified such that the segmented foetus could be accommodated inside its abdominal region. In a separate project, the segmented foetus will be used to verify new approaches toward semi-automated segmentation.