Comparison of optical detection system, PVDF detection system, and PVDF needle hydrophone for optoacoustic tomography
Optoacoustic tomography (PAT) is a two-dimensional medical imaging method that has the advantage of optical contrast and resolution of ultrasonic waves. The detection systems with a high sensitivity can be used for detecting small tumors, located deeply in human tissues, such as the breast. In this study, the sensitivity of existing ultrasonic detection systems has been compared experimentally with that by using thermoelastic waves as a broadband ultrasonic source. For the comparison, an optical stress transducer (OST), a polyvinylidene difluoride (PVDF) sheet and a calibrated PVDF needle hydrophone were used. To ensure all of the detection systems interrogated by the same ultrasonic field, a small optical instrument that fixed the generating laser head was constructed. The sensitivity was evaluated by measuring signal-to-noise ratios (SNRs) and noise equivalent pressures (NEPs). The PVDF system, with a 4-kPa NEP has a 22 dB better performance than the OST. The OST showed nearly the same sensitivity as the hydrophone for detecting ultrasound waves at a 1-cm distance in water. PVDF detection system provides a useful tool for imaging of soft tissues because of its high sensitivity and broad detection range.
M. Hejazi：Medical Physics and Bioengineering Department, Faculty of Medicine, Tehran University of Medical Sciences, Tehran, Iran, Research Centre for Science and Technology in Medicine, RCSTIM
A. Ahmadian：Medical Physics and Bioengineering Department, Faculty of Medicine, Tehran University of Medical Sciences, Tehran, Iran, Research Centre for Science and Technology in Medicine, RCSTIM
A. Amjadi：Institute of Physics, Sharif University, Tehran, Iran
备注：M. Hejazi is the author to whom the correspondence should be addressed, her e-mail address is firstname.lastname@example.org
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