Marker system and related stereotactic procedure

Abstract

Repeat fixation for medical procedures is accomplished using a non-invasive locator, specifically a bite plate. The bite plate has at least three fiducial markers on it. The fiducial markers may be LEDs, radiopaque markers for angiography or computerized tomography (CT) imaging or magnetic resonance markers for magnetic resonance (MR) imaging. By detecting the position of the markers, the position of features within the patient (such as a brain tumor or other intracranial target to which radiation is to be applied) can be determined with great precision. Since the bite plate has been molded to uniquely fit to the patient's teeth, it may be removed after an initial imaging of the patient. The bite plate may then be re-attached one or more times to the teeth. An alternate embodiment uses a head ring or head holder such as a head mask system with the LEDs thereon. The head ring is useful for single fraction treatments. A comparison is made between the relative patient position and the position of a medical device and a desired relative positioning. One or more error signals are the result of the comparison and are used for display purposes such that a person may manually null or minimize the errors or as feedback control signals for automatic error correction.