Biophotonics in Australia 2006. Optical coherence tomography. Outline. Optical
coherence tomography. • Tissue optics. • Speckle as a carrier of information.
Tissue imaging with optical coherence tomography
David Sampson School of Electrical, Electronic, & Computer Engineering
Outline Optical coherence tomography • Tissue optics • Speckle as a carrier of information • Limits on ultrahigh (1 µm) resolution • Alternative non-scanning holographic approach • Medical imaging - upper airway
Biophotonics in Australia 2006
Optical coherence tomography
Experimental results - microspheres
Hillman et al., Opt. Lett., p.190, 2006 Biophotonics in Australia 2006
Optical coherence tomography
What got everyone in OCT very excited
Ultrahigh resolution in Xenopus Laevis • • • • •
5-fs 800-nm mode-locked Ti:Sapphire laser 1-µm axial and 5-µm transverse Synthesis of images - not real time imaging Strongly confocal - focus set at different depths Dispersion compensated at each depth
Biophotonics in Australia 2006
W. Drexler, U. Morgner, F. X. Kärtner, C. Pitris, S. A. Boppart, X. D. Li, E. P. Ippen, J. G. Fujimoto, In vivo ultrahighresolution optical coherence tomography, Opt. Lett. 24 (1999) 1221-1223
Optical coherence tomography
Effects of absorption and dispersion
Hillman et al., Opt. Express, 2005, p1861 Biophotonics in Australia 2006
Optical coherence tomography
Reconstructed set of images at each angle
500 µm
500 µm Biophotonics in Australia 2006
Optical coherence tomography
Obstructive sleep apnoea “Repetitive collapse of upper airway during sleep” • Common – 4% of population • Massive economic impact: $10B pa in Australia • Common treatments: CPAP, MAD, surgery • Treatments are – empirical – often ineffective or poorly tolerated – not tailored to individuals • Huge market – e.g. RESMED - $700m Australian company supplying CPAP treatment • Increased likelihood of – Stroke – Heart attack – Car accident – ADHD in children Biophotonics in Australia 2006
Optical coherence tomography
Current options are not suitable •
X-ray computed tomography – Ionising radiation, short term because of dose
•
MRI – Noisy, claustrophobic, short term because of expense
•
Video endoscopy – Not quantitative
Biophotonics in Australia 2006
Optical coherence tomography
Clinical measurements – Compliance Important physiological parameters such as compliance are measurable
Airway images at different applied pressures. Red - 3 cm H2O Blue - 9 cm H2O Green - 12 cm H2O Biophotonics in Australia 2006
Optical coherence tomography