Multimodal Haptic Simulation for Ventriculostomy Training.

Freehand ventriculostomy is a frequent surgical procedure and is among the first ones that junior neurosurgery residents learn. Although training simulators exist, none has been adopted in the clinical routine to train junior residents. This paper focuses on a novel multimodal haptic training simulator that will lift the limitations of current simulators. We thus propose an architecture that integrates (1) visual feedback through augmented MRIs, and (2) a physical mock-up of the patient's skull to (3) active haptic feedback.

Real Time Estimator to Perform Targeted Biopsies With a Free-Wrist Robot Despite Large Deformations of the Insertion Orifice.

In the context of keyhole surgery, and more particularly of uterine biopsy, the fine automatic movements of a surgical instrument held by a robot with 3 active DOF's require an exact knowledge of the point of rotation of the instrument. However, this center of rotation is not fixed and moves during an examination. This paper deals with a new method of detecting and updating the interaction matrix linking the movements of the robot with the surgical instrument. This is based on the method of updating the Jacobian matrix which is named the "Broyden method". It is able to take into account body tissue deformations in real time in order to improve the pointing task for automatic movements of a surgical instrument in an unknown environment.

Precisely positioning the tip of an instrument inserted through an orifice with a free wrist robot: application to prostate biopsies.

PURPOSE: Robots with a spherical unactuated wrist can be used for minimally invasive surgery. With such a robot, positioning the wrist center controls the instrument tip position when assuming that the insertion site behaves like a lever with a fixed and known fulcrum. In practice, this assumption is not always respected. In this paper we first study the practical consequences of this problem in terms of tip precision positioning. We then propose a robotic control scheme that improves the precision compared to the fixed point assumption approach. METHODS: In the first part of the paper, data recorded during robot-assisted transrectal needle positioning for prostate biopsies (nine patients) are exploited to quantify the positioning error induced by the use of a fixed point hypothesis in the positioning process. In the second part of the paper advanced control techniques allow for the online identification of a locally linear system that describes a model characterized by anisotropy and center displacement. A laboratory apparatus is used to demonstrate the resulting improvement on tip positioning precision. RESULTS: Errors obtained by processing the clinical data reach 7.5 mm at the tip in average. Errors obtained with the laboratory apparatus drop from 2.4 mm in average to 0.8 mm when using real-time model update.