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Proceedings Paper

Non-contact photoacoustic tomography with a laser Doppler vibrometer
Author(s): Guan Xu; Cheng Wang; Ting Feng; David E. Oliver; Xueding Wang
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Paper Abstract

Most concurrent photoacoustic tomography systems are based on traditional ultrasound measurement regime, which requires the contact or acoustic coupling material between the biological tissue and the ultrasound transducer. This study investigates the feasibility of non-contact measurement of photacoustic signals generated inside biomedical tissues by observing the vibrations at the surface of the tissues with a commercial laser Doppler vibrometer. The vibrometer with 0- 2MHz measurement bandwidth and 5 MHz sampling frequency was integrated to a conventional rotational PAT data acquisition system. The data acquisition of the vibrometer was synchronized to the laser illumination from an Nd:YAG laser with output at 532nm. The laser energy was tuned to 17.5mJ per square centimeter. The PA signals were acquired at 120 angular locations uniformly distributed around the scanned objects. The frequency response of the measurement system was first calibrated. 2-inch-diamater cylindrical phantoms containing small rubber plates and biological tissues were afterwards imaged. The phantoms were made from 5% intralipid solution in 10% porcine gelatin to simulate the light scattering in biological tissue and to backscatter the measurement laser from the vibrometer. Time-domain backprojection method was used for the image reconstruction. Experiments with real-tissue phantoms show that with laser illumination of 17.5 mJ/cm2 at 532 nm, the non-contact photoacoustic (PA) imaging system with 15dB detection bandwidth of 2.5 MHz can resolve spherical optical inclusions with dimension of 500μm and multi-layered structure with optical contrast in strongly scattering medium. The experiment results prompt the potential implementation of the non-contact PAT to achieve “photoacoustic camera”.

Paper Details

Date Published: 3 March 2014
PDF: 7 pages
Proc. SPIE 8943, Photons Plus Ultrasound: Imaging and Sensing 2014, 894332 (3 March 2014); doi: 10.1117/12.2040290
Show Author Affiliations
Guan Xu, Univ. of Michigan Medical School (United States)
Cheng Wang, Univ. of Michigan Medical School (United States)
Ting Feng, Univ. of Michigan Medical School (United States)
David E. Oliver, Polytec, Inc. (United States)
Xueding Wang, Univ. of Michigan Medical School (United States)

Published in SPIE Proceedings Vol. 8943:
Photons Plus Ultrasound: Imaging and Sensing 2014
Alexander A. Oraevsky; Lihong V. Wang, Editor(s)

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