A method of manufacturing a leadless marker for localizing the position of a target within a patient. According to one embodiment, the method includes providing a ferromagnetic element positioning a coil of an inductor at least around a portion of the ferromagnetic element, wherein the coil comprises a plurality of windings of a conductor and positioning the ferromagnetic element such that the radiographic and magnetic centroids of the marker are at least substantially coincident. The marker does not have external electrical lead lines extending through the casing. The ferromagnetic element is at least partially within the inductor. The ferromagnetic element has a volume such that when the marker is in an imaging magnetic field having a field strength of 1.5 T and a gradient of 3 T/m, then the force exerted on the marker by the imaging magnetic field is not greater than gravitational force exerted on the marker.
