Simulation of scattered radiation during intraoperative imaging in a virtual reality learning environment.

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.