Comparison between X-ray stereoscopy and laser Doppler vibrometry for motion measurement in biomechanics
Faculty of Sciences. Physics
OPTICAL MEASUREMENT TECHNIQUES FOR STRUCTURES & SYSTEMS2 (OPTIMESS2012)
5th International Conference on Optical Measurement Techniques for, Structures and Systems2 (OPTIMESS), APR 04-05, 2012, Antwerp, BELGIUM
, p. 359-368
University of Antwerp
Measurement of micro-motion inside small objects is of interest to biomechanics. We propose a method using a combination of a single point x-ray source and stereoscopy to accurately measure motion within opaque objects, which is not possible with laser Doppler vibrometry. From two x-ray projection recordings with a 90 degrees separation angle, the 3D coordinates of marker points can be determined. By synchronizing the x-ray exposure time to the motion event, a moving marker leaves a trace in the image of which the gray scale is linearly proportional to the marker velocity, and thus time. We thus obtain the path of motion in 3D, using the gray scales in the shadow images. To obtain the 3D motion with laser Doppler vibrometry, an expensive and complicated setup is needed; moreover, the internal structure under study should be visually exposed for three laser beams from different angles, which is not always possible for many biological systems. As a demonstration, the motion of the middle ear ossicles was measured using our x-ray stereoscopy method, and compared with laser vibrometry measurements.