Abstract: The present invention provides a stereotactic medical procedure performed on an anatomy of a patient, and a system used for the procedure. Two or more references such as fiducial markers are used sequentially or consecutively in the medical procedure. In an embodiment, the invasive affixation of those references and the invasive portion of the medical procedure can be consolidated in a short and compact operation. The trauma and pain suffered by a patient is thus alleviated. Moreover, the present invention can expand the application of image guiding technique to many medical procedures that would otherwise preclude such application.