In the course of developing a training simulator for puncture, a novel approach is proposed to render in realtime the ultrasound (US) image of any 3D model. It is combined with the deformation of the soft tissues (due to their interactions with a needle and a probe) according to their physical properties. Our solution reproduces the usual US artifacts at a low cost. It combines the use of textures and ray-tracing with a new way to efficiently render fibrous tissues. Deformations are handled in real-time on the GPU using displacement functions. Our approach goes beyond the usual bottleneck of real-time deformations of 3D models in interactive US simulation. The display of tissues deformation and the possibilities to tune the 3D morphotypes, tissue properties, needle shape, or even specific probe characteristics, is clearly an advantage in such a training environment.

Background There is a general agreement upon the importance of acquiring laparoscopic skills outside the operation room through simulation-based training. However, high-fidelity simulators are cost-prohibitive and elicit a high cognitive load, while low-fidelity simulators lack effective feedback. This paper describes a low-fidelity simulator bridging the existing gaps with affine velocity as a new assessment variable. Primary validation results are also presented. Methods Psycho-motor skills and engineering key features have been considered e.g. haptic feedback and complementary assessment variables. Seventy-seven participants tested the simulator (17 expert surgeons, 12 intermediates, 28 inexperienced interns, and 20 novices). The content validity was tested with a 10-point Likert scale and the discriminative power by comparing the four groups’ performance over two sessions. Results Participants rated the simulator positively, from 7.25 to 7.72 out of 10 (mean, 7.57). Experts and intermediates performed faster with fewer errors (collisions) than inexperienced interns and novices. The affine velocity brought additional differentiations, especially between interns and novices. Conclusion This affordable haptic simulator makes it possible to learn and train laparoscopic techniques. Self-assessment of basic skills was easily performed with slight additional cost compared to low-fidelity simulators. It could be a good trade-off among the products currently used for surgeons' training.

Articular and soft tissue punctions or injections are widely used for the diagnosis and the treatment of rheumatic disorders. Ultrasound is increasingly used to guide these interventions in order to correctly position the needle in the target area, and thereby improve the efficiency and safety of the procedure. During their learning, medical students need to practice in order to master the manipulation of the needle and the ultrasound probe at the same time and acquire enough skills before practicing in a real patient. To offer a risk-free training for apprentices, we present in this paper the design and development of a simulator based on Haptics and Virtual Reality. We described in particular two main aspects of our prototype: (i) the model of forces involved in the needle insertion and their haptic rendering; (ii) the 2D ultrasound image rendering of the virtual environment. Their combination provides the student with a realistic experience. An additional 3D view is also presented, that serves as pedagogical tool useful in the learning process. Experimental validation and preliminary evaluation by the medical partner show that our prototype exhibits sufficient stability and realism for a good immersion in the training scene.