MRI Center Seminar, "A Single Camera System for 6-DOF Patient Motion Measurement in MRI"

An optically based, rigidbody 6‐DOF measurement system optimized for prospective motion correction in Magnetic Resonance Imaging is described. By optimizing system capabilities to the specific applications requirements, the 6‐DOF measurement is accomplished using a single camera and simple 3‐disc fiducial at rates of 50 Hz. The algorithm utilizes successive approximation to solve the 3‐point pose problem for small deflection angles. Convergence to sub‐microradian levels occurs within 20 iterations for angles in an approximate half‐radian (29 degree) arc. The absolute accuracy of the instrument is 10‐100 microns for translational and < 100 microradians (0.005 degrees) for rotational motions. Results for head nodding and speech tasks are presented for subjects in the MRI scanner, and the instrument results are compared to standard Prospective Acquisition Correction (PACE).

Dr. Chester Wildey
Founder, MRRA Inc.

Dr. Chester Wildey has more than 25 years of experience in electronic measurement systems. He has designed electro-optic instruments for customers including the Federal Bureau of Investigation and the Federal Reserve Bank. Recent development work focuses on devices supporting brain research. These include a single camera 6-DOF patient motion measurement system for use in MRI, and development of a new optode for use with fNIRS scanners. In 2009, Wildey founded MRRA Inc. to promote the use of these new technologies. More information may be found at

August 25, 2011, 12:30 pm
Broun Hall 239
Additional Info:

If you have any questions please contact the MRI Research Center office at 334.844.6747 or email Tom Denney ( or Julie Rodiek  ( The seminar is open to the public and no RSVP is necessary.

The MRI Seminar Series has been recorded and is on the engineering server. If you would like to view one of these talks please contact Julie Rodiek at to obtain the weblink and password information. A list of past seminars can be found at