Magneto-optic hybrid 3-D sensor for surgical navigation

Abstract

The objective of the work described in this paper was to develop an accurate three dimensional (3-D) sensory system without a lineof- sight requirement for surgical navigation inside the body. Although magnetic sensors seem to be particularly suitable for this purpose, their accuracy is affected by metallic objects, which can hardly be avoided in a surgical environment. We propose a new magneto-optic hybrid 3-D sensor configuration that overcomes this limitation. Unlike previous hybrid systems, both the receiver and transmitter of the magnetic sensor are mobile, thereby permitting them to be positioned flexibly and adaptively so as to minimize inaccuracies arising from the presence of peripheral metallic objects. The 3-D position and orientation of the transmitter are measured by an optical sensor in order to accurately track the transformation between the coordinate systems of the magnetic and optical sensors. The effects of the distance between the receiver and the transmitter and their respective distances from metallic objects on the accuracy of the system were evaluated by experiments both in the laboratory and in the operating room.