Optical coherence tomography (OCT) is a promising candidate for monitoring the bottom of the drilled channel during cochleostomy to prevent injury to the critical structure under the bone tissue. While the thickness of the overlaying bone tissue is changed during the drilling process, the wave front of the backscattered light is also altered, resulting in changing speckle patterns of the observed structures in the sequential historical scans. By averaging the different patterns in these scans, named history compounding, the speckles can be reduced and the detection of critical structure becomes much easier. Before averaging, the refractive index of bone tissue 𝑛𝑏 has to be compensated so that the speckles of the same structure in different historical scans can be aligned together. An accurate method for measuring the refractive index n_b using OCT is presented. Experiments were conducted to evaluate history compounding and the new technique is proved to be an effective, flexible and intuitive speckle reduction technique for OCT guided cochleostomy as well as hard tissue ablation of other kind.

Date Published: 20 March 2013
PDF: 6 pages
Proc. SPIE 8571, Optical Coherence Tomography and Coherence Domain Optical Methods in Biomedicine XVII, 85713H (20 March 2013); doi: 10.1117/12.2006979

Published in SPIE Proceedings Vol. 8571:
Optical Coherence Tomography and Coherence Domain Optical Methods in Biomedicine XVII
James G. Fujimoto; Joseph A. Izatt; Valery V. Tuchin, Editor(s)