Three-dimensional touch interface for medical education.

We present the technical principle and evaluation of a multimodal virtual reality (VR) system for medical education, called a touch simulator. This touch simulator comes with an innovative three-dimensional (3-D) touch sensitive input device. The device comprises a six-axis force-torque sensor connected to a tangible object representing the shape of an anatomical structure. Information related to the point of contact is recorded by the sensor, processed, and audiovisually displayed. The touch simulator provides a high level of user-friendliness and fidelity compared to other purely graphically oriented simulation environments. In this paper, the touch simulator has been realized as an interactive neuroanatomical training simulator. The user can visualize and manipulate graphical information of the brain surface or different cross-sectional slices by a finger-touch on a brain-like shaped tangible object. We evaluated the system by theoretical derivations, experiments, and subjective questionnaires. In the theoretical analysis, we could show that the contact point estimation error mainly depends on the accuracy and the noise of the sensor, the amount and direction of the applied force, and the geometry of the tangible object. The theoretical results could be validated by experiments: applying a normal force of 10 N on a 120 mm x 120 mm x 120 mm cube causes a maximum error of 2.5 +/- 0.7 mm. This error becomes smaller when increasing the contact force. Based on the survey results, the touch simulator may be a useful tool for assisting medical schools in the visualization of brain image data and the study of neuroanatomy.

Haptic device for a ventricular shunt insertion simulator.

In this paper we propose a new one-degree-of-freedom haptic device that can be used to simulate ventricular shunt insertion procedures. The device is used together with the BRAINTRAIN training simulator developed for neuroscience education, neurological data visualization and surgical planning. The design of the haptic device is based on a push-pull cable concept. The rendered forces produced by a linear motor connected at one end of the cable are transferred to the user via a sliding mechanism at the end-effector located at the other end of the cable. The end-effector provides the range of movement up to 12 cm. The force is controlled by an open-loop impedance algorithm and can become up to 15 N.

BrainTrain: brain simulator for medical VR application.

The brain is known as the most complex organ in the human body. Due to its complexity, learning and understanding the anatomy and functions of the cerebral cortex without effective learning assistance is rather difficult for medical novices and students in health and biological sciences. In this paper, we present a new virtual reality (VR) simulator for neurological education and neurosurgery. The system is based on a new three-dimensional (3D) user-computer interface design with a tangible object and a force-torque sensor. The system is combined with highly interactive computer-generated graphics and acoustics to provide multi-modal interactions through the user's sensory channels (vision, tactile, haptic and auditory). The system allows the user to feel the simulated object from its physical model that formed the interface device, while exploring or interacting with the mimicked computer-generated object in the virtual environment (VE). Unlike other passive interface devices, our system can detect the position and orientation of the interacting force in real-time, based on the system's set-up and a force-torque data acquisition technique. As long as the user is touching the model, the positions of the user's fingertip in the VE can be determined and is synchronized with the finger's motion in the physical world without requirement of an additional six-degree-of-freedom tracking device. The prior works have shown the use of the system set-up in medical applications. We demonstrate the system for neurological education and neurosurgery as a recent application. The main functions of the simulator contribute to education in neuroanatomy and visualization for diagnostic and pre-surgery planning. Once the user has touched the model, the system will mark the associated anatomy region and will provide the information of the region in terms of text note and/or sound. The user can switch from anatomy to the brain's function module, which will give details of motor, sensory or other cortical functions associated to the touch areas. In addition, the user can generate and visualize arbitrary cross-sectional images from corresponding to the magnetic resonance imaging (MRI) datasets either for training or for diagnostic purpose. The user can manipulate the cross-section image interactively and intuitively by moving the finger on the interface device.