Optoacoustic tomography (PAT) is a two-dimensional medical imaging method that has the advantage ofoptical contrast and resolution of ultrasonic waves. The detection systems with a high sensitivity can beused for detecting small tumors, located deeply in human tissues, such as the breast. In this study, thesensitivity of existing ultrasonic detection systems has been compared experimentally with that by usingthermoelastic 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 instrumentthat 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 hasa 22 dB better performance than the OST. The OST showed nearly the same sensitivity as the hydrophonefor detecting ultrasound waves at a 1-cm distance in water. PVDF detection system provides a useful toolfor imaging of soft tissues because of its high sensitivity and broad detection range. 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. For this 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 hasa 22 dB better performance than the OST. The OST showed nearly the same sensi tivity 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.