Perhaps the only comparable study to this one is the study of Wang et al., who reported on the usage of CamC [16], a prototype system used during a limited round of early clinical trials [26, 28]. In that study, approximately 40 cases in which a camera-augmented mobile C-arm x-ray system was used intra-operatively, were documented and analyzed. A workflow-oriented study was used to reveal that radiation exposure can be significantly reduced in specific workflow steps, due to the augmentation of the x-ray image with a real-time camera video stream. These steps, such as patient localization, skin incision placement or tool posture adaptation, are common to many surgical procedures. Thus, due to the study, very specific advantages of AR visualization modes were found, sometimes unexpectedly, for particularly common workflow steps.