The positioning of bone anchored hearing implants can be a difficult task due to the varying size and thickness of the mastoid bone. An assessment of the anatomical situation based on computed tomography (CT) data provides helpful insights. The positioning of the implant in the 3D CT data, however, is not easily achievable. The goal of this project is the development of a visualization tool that allows for fast and intuitive positioning of a 3D hearing implant geometry in CT data of the petrous bone. To reasonably restrict the possible user-interactions - and therefore ease the use of the tool - a geometric model of the petrous bone region will be automatically reconstructed from CT data. Based on the reconstructed anatomical model visualization tools are provided that aid in finding a suitable position of the implant.