1. A tracking and imaging system for following a position and orientation of at least one invasive device within a subject, comprising: a) an invasive device; b) an electromagnetic (EM) creation means attached to the invasive device, for creating an electromagnetic field of known geometry, and known electromagnetic flux defined by a plurality of known electromagnetic field vectors within the subject, EM field creation means comprising: i. a master oscillator for setting a standard timing signal; ii. a control computer coupled to the master oscillator and responsive to the standard timing signal; and iii. a plurality of N transmit branches, wherein N.gtoreq.1, each of the transmit branches comprises: A. transmit frequency offset means for creating an RF transmit signal of a frequency determined by the control computer based upon the standard timing signal, B. a gating means coupled to the transmit frequency offset means and responsive to the control computer adapted for selectively passing or not passing the RF transmit signal, C. an amplifier responsive to the control computer for receiving the RF transmit signal from the gating means and amplifying the RF transmit signal with a gain determined by the control computer, and D. a transmit coil coupled to the amplifier for creating the electromagnetic field of known geometry from the RF transmit signal; c) a radiofrequency (RF) receiver for detecting the electromagnetic field vector at a plurality of M greater than 5 selected locations; d) imaging means for acquiring a medical diagnostic image; and e) a tracking means for computing a position and an orientation relative to the acquired medical diagnostic image of the EM field creation means being substantially said position and said orientation of the invasive device, the tracking means being responsive to the electromagnetic field vectors detected by the RF receiver at the M selected locations.