Method for safely and efficiently navigating magnetic devices in the body

A method of turning a magnet element at an operating point inside a patient's body from an initial direction to a desired final direction by moving a source magnet outside the body, the method comprising the steps of:

• (a) providing means for determining and maintaining during a procedure the location and orientation of the magnet element relative to the location and orientation of the external source magnet;
• (b) choosing desired field vectors in the patient frame as a series of angularly spaced vectors which lie in the plane of the initial and final vectors and entering them in a processor;
• (c) entering the position and direction of the vectors into a processor by a means of specifying and displaying the field and communicating with the processor;
• (d) calculating field directions at the operating point in the reference frame of the patient by translating the desired vectors into the reference frame of the magnet;
• (e) transforming each one of the sequence of vectors into the reference frame of the source magnet;
• (f) calculating a surface of constant field strength of desired value in the magnet frame;
• (g) locating each of the field vectors on the appropriate latitude of the surface of constant field strength corresponding to the correct transformed direction of the field vector;
• (h) for each pair of sequential vectors of the total set, calculating the minimum motion of the source magnet required to change the field direction, taking advantage of the azimuthal symmetry of the magnet field;
• and
• (i) executing the desired step turns by articulating the source magnet.