Whilst computers are more and more used in the medical and surgical domains, medical education is still very conservative. However, new information technology could bring a lot to this area. In particular, simulators are of paramount interest: they would allow one both to experiment with surgical or imaging techniques for a wide range of pathologies without the need for patients and to quantitatively evaluate the trainees' performances. Ultrasound imaging is a typical area where virtual reality may change educational uses. This paper describes an ultrasound imaging simulator dedicated to the training of physicians for the detection of deep venous thromboses of the lower limbs. Like this one, a lot of other pathologies of soft tissue are diagnosed using ultrasound imaging. Because this examination is difficult and operator-dependent, developing a simulator is very useful to give common databases of pathological samples on which physicians can both experiment with image acquisition and evaluate their understanding of clinical cases. Real-time simulation is mandatory. An ultrasound imaging simulator has been developed and is being tested. This paper presents the hardware and software components of the simulator and describes the status of this project. Copyright © 2000 John Wiley & Sons, Ltd.

The registration of multiple 3D data sets obtained with a laser range finder is examined. A sensor calibration technique based on the conjunction of a mathematical camera model, the N-planes B-spline (NPBS), with an accurate mechanical calibration setup, is proposed. An algorithm for recovering the rigid transformation (rotation and translation) between the two sets of 3D coordinates obtained by the calibrated imaging range sensor is developed. Its input is sets of points lying on the surface of the object. This input is converted into an octree-spline that allows point-to-surface distances to be computed quickly. A robust nonlinear least-squares minimization technique then finds the optimal pose by minimizing the sum of square distances between the two sets of 3D coordinates. The algorithm has been applied to matching human faces with highly accurate results.>

A method is presented for modeling and calibration of sensors, to reach an accuracy similar in magnitude to the resolution of the sensors. The authors focus on camera and range image calibration. They show the limitations of existing methods, and present an approach and camera calibration using mathematical B-Spline functions. This method is abbreviated as NPBS (N-Planes B-Spline). It is an extension of the two-planes method, but relies on pure mathematical modeling based on spline approximation theory. The mathematical modeling is combined with a calibration device that enables accurate data acquisition to calibrate a camera and a light plane independently. Experimental results are presented showing accuracy on the determination of a scattered plane.>