Computer assisted surgery with the help of positioning systems

Intelligent instruments assist the surgeon with intraoperative orientation during difficult operations, for example on the skull or in the ear-nose-throat area, by determining the position of the tip of the instrument in space during the operation. The basic requirements of intelligent instruments are: 1) mostly, high precision and dependability of the positioning system; 2) an easy understandable way in which the CT/MRI data, including the current position of the instrument, is visualized, 3) and a low price. Reported is the advantage or disadvantage of different positioning systems, like mechanical arms, electromagnetic units, optical systems or ultrasonic devices.