A photoacoustic technique for monitoring absorber size and concentration is presented. The technique relies on analyzing the power spectra of the radio-frequency signals and taking into account the receiving transducer response in order to remove system dependencies. By normalizing the power spectra, parameters derived from ultrasound tissue characterization (spectral slope and midband fit) can be obtained. Tissue mimicking phantoms were constructed using black polystyrene beads of various sizes and concentrations as absorbers. The spectral slope decreased by 0.63 dB/MHz when the size of the particle increased from 1 μm to 10 μm at every bead concentration. The midband fit was ~4 dB higher for the 10 μm particle and increased linearly with concentration. These results suggest that photoacoustic radiofrequency spectroscopy (PA-RFS) can potentially monitor changes in absorber size and concentration thus improving the ability of photoacoustic imaging to distinguish structural tissue variations.

Date Published: 4 March 2013
PDF: 6 pages
Proc. SPIE 8581, Photons Plus Ultrasound: Imaging and Sensing 2013, 85813W (4 March 2013); doi: 10.1117/12.2004991

Published in SPIE Proceedings Vol. 8581:
Photons Plus Ultrasound: Imaging and Sensing 2013
Alexander A. Oraevsky; Lihong V. Wang, Editor(s)