Correcting photoacoustic signals for fluence variations using acousto-optic modulation.
We present a theoretical concept which may lead to quantitative photoacoustic mapping of chromophore concentrations. The approach supposes a technique capable of tagging light in a well-defined tagging volume at a specific location deep in the medium. We derive a formula that expresses the local absorption coefficient inside a medium in terms of noninvasively measured quantities and experimental parameters and we validate the theory using Monte Carlo simulations. Furthermore, we performed an experiment to basically validate the concept as a strategy to correct for fluence variations in photoacoustics. In the experiment we exploit the possibility of acousto-optic modulation, using focused ultrasound, to tag photons. Results show that the variation in photoacoustic signals of absorbing insertions embedded at different depths in a phantom, caused by fluence variations of more than one order of magnitude, can be corrected for to an accuracy of 5%.
Biomedical Photonic Imaging group, MIRA Institute for Biomedical Technology and Technical Medicine, University of Twente, PO Box 217, 7500 AE Enschede, The Netherlands.
K
K
Daoudi
A
A
Hussain
E
E
Hondebrink
W
W
Steenbergen
D007089:Image Enhancement / Q000379:methods*; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D008029:Lighting / Q000379:methods*; D008856:Microscopy, Fluorescence / Q000379:methods*; D061088:Photoacoustic Techniques / Q000379:methods*