# On the Design and Implementation of a Mixed-Platform Collaborative Virtual RAS Planner
## 2 Related Work  
Training in robotic surgery entails two fundamental aspects: skill and knowledge [7]. While skill training is usually achieved using simulators, which allow the surgeon's skills to be polished without putting a patient at risk, knowledge training usually involves recording RAS procedures and then displaying them as teaching elements. In both cases, the use of virtual 3D models, the interaction paradigms of mixed, virtual, extended, and augmented reality technologies, or even the use of printed 3D models, can play a relevant role [8]. In this regard, Virtual Surgery Planning (VSP) can be defined as the use of virtual information to improve the surgical planning process. VSP has been explored before in the academic literature, as in [9] where VSP was used to aid robot-assisted laparoscopic partial nephrectomy, or in [10] where VSP was used in mandibular reconstruction. Both works rely solely on virtual 3D models and do not exploit complex interaction mechanisms like those we propose. However, both works conclude that VSP is viable and can improve the ability of surgeons to plan surgical procedures. Some other academic works have explored the use of virtual models for RAS planning, such as [11], where IRISTM is used and assessed. This proprietary system enables physicians to view a 3D model of the patient anatomy on which they will be operating and helps devise a plan for the procedure. The authors conclude that virtual planning can predict most of the operative findings in robot-assisted nephrectomy. In contrast to what we propose, none of these three works are collaborative. As reported in the literature, the use of VSP can help decide the type of surgical approach [12], understand the depth of a tumour [12], identify the best positions and orientations for the trocars [13], increase the surgeon's confidence [8], or even predict the outcome of the surgical intervention [11]. Moreover, the possibility of collaborative or even remote planning can significantly increase its benefits, optimizing the surgical process and allowing better interdisciplinary communication [14]. However, most of the works published in the academic literature focus on non-collaborative applications. There are, nevertheless, some exceptions. For instance, in [15], a collaborative VR environment to assist liver surgeons in tumour surgery planning is presented. The system allows surgeons to define and adjust virtual resections on patient-specific organ 3D surfaces and 2D image slices, while changes in both modalities are synchronized. Additionally, the system includes a real-time risk map visualisation that displays safety margins around tumours. Another work in which collaborative planning is proposed is [16]. The authors use a collaborative face-to-face system using MR devices in which various surgeons can jointly inspect a 3D model of the target tissues in cases of laparoscopic liver and heart surgery. This application includes tools for model transformation, marker positioning, 2D medical image viewing, and section planes. However, the collaboration is in situ and is symmetrical, unlike ours, which can be either symmetrical or asymmetrical and can be both in situ and remotely. There are other works that apply collaborative MR to the surgical field. For instance, the ARTEMIS system proposed in [17] enables skilled surgeons and novices to work together in the same virtual space, while approaching the problem of remote collaboration through a hybrid interface: on the one hand, expert surgeons in remote sites use VR to access a 3D reconstruction of a patient's body and instruct novice surgeons on complex procedures; on the other hand, novice surgeons in the field focus on saving the patient's life while being guided through an AR interface. This work is interesting because it combines AR and VR, but focuses on surgical telemetroning and not on surgical planning for RAS, as we propose. Similarly, in [18], the benefits of an AR-based telemetroning system on the coaching and confidence of medical personnel are explored.