Certain embodiments of the present invention provide a method for detecting an electromagnetic field in an imaging system including emitting an electromagnetic field with an electromagnetic transmitter, sensing an electromagnetic field with an imaging system detector, and reading a field image from the detector based at least in part on the electromagnetic field. The imaging system detector is capable of reading an object image and a field image. The detector may be an amorphous silicon flat panel x-ray detector. The electromagnetic transmitter may be used in surgical navigation. The position of a surgical device, instrument, and/or tool may be determined based in part on the field image. The detector may be coordinated to acquire the field image when the electromagnetic transmitter is emitting an electromagnetic field. The detector may be coordinated to acquire the object image when the electromagnetic transmitter is not emitting an electromagnetic field.