Publikationen

Purpose Scattered radiation, which occurs when using a C-arm for intraoperative radiography, can be better understood through interactive visualization. We developed a virtual reality (VR) approach for the simulation of scattered radiation (SSR) as part of a C-arm training system. In VR, it is important to avoid cyber sickness, which is often caused by increased latency between head motion and image presentation inside the head-mounted display. As the latency requirement interferes with the computational complexity of the SSR, the goal has been to maintain a low latency during the simultaneous computation of the SSR on moderate-cost consumer hardware. Methods For use with a VR C-arm simulator, a CUDA-based Monte Carlo SSR has been improved to utilize GPU resources unused by the VR image generation. Resulting SSR data are visualized through volume rendering with pseudo-colored scattered radiation superimposed onto the virtual operating room. The resulting interactive VR–SSR environment was evaluated with operating room personnel (ORP) and surgeons using questionnaires. Results Depending on the imaged body part and computation parameters, the required computation time to complete one SSR run was between 1.6 and 4.2 s (ankle) and between 7.9 and 14.9 s (thigh), and VR frame times from 11 to 12 ms (95th percentile). The system was evaluated with ORP (n = 46) and surgeons (n = 25). The median of professional C-arm experience was 5 (range 1 to 34) years (ORP) and 12.5 (range 2 to 48) years (surgeons), respectively. The demonstrated prototype was found useful by 78% of ORP and 88% of the surgeons. On a Likert scale, more than 90% of both groups “agreed fully” that the presented way of visualizing SSR in VR helps understanding intraoperative exposure to scattered radiation. Conclusions Leveraging off-the-shelf computer equipment, the feasibility of SSR and VR for interactive training has been demonstrated. Evaluation participants showed a high interest for the presented approach. Feedback suggests that the visualization experienced by the users helps understanding radiation hazards in the operating room.

The authors present a simulation-based ultrasonographic (US) training tool that can help improve the understanding of spatial relationships in US. Use of a game controller to simulate a US probe allows examination of different virtual three-dimensional (3D) objects. These 3D objects are either completely artificial simple geometric objects (eg, spheres, tubes, and ellipsoids, or more complex combinations thereof) or derived from photographed gross anatomic data (eg, the Visible Human dataset [U.S. National Library of Medicine]) or clinical computed tomographic (CT) data. The virtual US probe allows infinitely variable real-time positioning of a “slice” that is displayed as a two-dimensional (2D) cross-sectional image and as part of a 3D view. Combining the 2D and 3D views helps elucidate the spatial relationships between a 3D object and derived 2D images. This training tool provides reliable real-time interactivity and is widely available and easily affordable, since it utilizes standard personal computer technology and off-the-shelf gaming hardware. For instance, it can be used at home by medical students or residents as a complement to conventional US training. In the future, this system could be adapted to support training for US-guided needle biopsy, with use of a second game controller to control the biopsy needle. Furthermore, it could be used as a more general interactive visualization tool for the evaluation of clinical 3D CT and magnetic resonance imaging data, allowing efficient and intuitive real-time creation of oblique multiplanar reformatted images. Online supplemental material is available for this article. ©RSNA, 2014

Mobile image intensifier systems (C-arms) are used frequently in orthopedic and reconstructive surgery, especially in trauma and emergency settings, but image quality and radiation exposure levels may vary widely, depending on the extent of the C-arm operator s knowledge and experience. Current training programs consist mainly of theoretical instruction in C-arm operation, the physical foundations of radiography, and radiation avoidance, and are largely lacking in hands-on application. A computer-based simulation program such as that tested by the authors may be one way to improve the effectiveness of C-arm training. In computer simulations of various scenarios commonly encountered in the operating room, trainees using the virtX program interact with three-dimensional models to test their knowledge base and improve their skill levels. Radiographs showing the simulated patient anatomy and surgical implants are “reconstructed” from data computed on the basis of the trainee s positioning of models of a C-arm, patient, and table, and are displayed in real time on the desktop monitor. Trainee performance is signaled in real time by color graphics in several control panels and, on completion of the exercise, is compared in detail with the performance of an expert operator. Testing of this computer-based training program in continuing medical education courses for operating room personnel showed an improvement in the overall understanding of underlying principles of intraoperative radiography performed with a C-arm, with resultant higher image quality, lower overall radiation exposure, and greater time efficiency. Supplemental material available at http://radiographics.rsna.org/lookup/suppl/doi:10.1148/rg.313105125/-/DC1.© RSNA, 2011