Patent ID: 8887551

Claim:
For use with a position sensor secured to an ultrasonic probe, the ultrasonic probe having an ultrasonic image plane, a method for determining a spatial relation that is maintained between a position and orientation of the position sensor and a position and orientation of the ultrasonic image plane, the method comprising: placing a position sensor at an arbitrary point and at an arbitrary rotational orientation on an ultrasonic probe, said ultrasonic probe having known dimensions that describe its geometrical shape; obtaining spatial coordinates of said position sensor; obtaining spatial coordinates of three points on an external surface of said ultrasonic probe, and using said three points to define an ultrasonic image plane, wherein the ultrasonic image plane is symmetric relative to said ultrasonic probe; obtaining spatial coordinates of a set of landmarks which have a known spatial relationship to said ultrasonic image plane, said spatial coordinates of said landmarks defining a direction in which said ultrasonic probe is directed within said ultrasonic image plane; obtaining spatial coordinates of a front point on a front facing surface of said ultrasonic probe, said front facing surface having a known relation with a reference axis of a scanning plane of said ultrasonic probe that defines where an ultrasonic image starts within said ultrasonic image plane, the spatial coordinates of the front point on the front facing surface of said ultrasonic probe and the direction in which said ultrasonic probe is directed within said ultrasonic image plane determining a spatial relation between the ultrasonic image plane and the front facing surface; and measuring the position and orientation of the probe sensor with respect to the front facing surface, and thereby determining the spatial relation maintained between the position sensor and the ultrasonic image plane.