fMRI headtracking using a single camera and a lightweight fiducial.

A single CCD/DSP camera based optical system affords six degree of freedom motion tracking for MRI applications with resolutions in the range of < 50 microradians and 10-100 microns. The fiducial target is a lightweight compact three dimensional pattern that allows efficient, centroid based algorithms to determine distance translation and angle rotation at rates of 30Hz. In-magnet tests measure the inherent magnet vibration as well as subject signatures such as those for respiration, speech, swallow and nod.