Photoacoustic imaging with attenuation rectification of different frequent components of photoacoustic signal

Photoacoustic tomography is a potential and noninvasive medical imaging technology. It combines the advantages of pure optic imaging and pure ultrasound imaging. Photoacoustic signals induced by a short pulse laser cover a wide spectral range. We have explored the influences of attenuation of photoacoustic signals, which vary according to frequencies, to the quality of reconstructed photoacoustic images. It reveals that the attenuation of low frequent components are less than that of high frequencies, and the latter is more important for photoacoustic imaging with high resolution. Based on the ultrasonic attenuation theory, the photoacoustic imaging with rectification of the attenuation of different frequent component was performed. The experiments results show that this method improves the resolution of reconstructed images, which improves from 0.3mm to 0.2mm. A Q-switched Nd:YAG laser operating at 1064nm was used as light source. The laser had a pulse width of 6ns and a repetition frequency of 20Hz. A needle PVDF hydrophone with diameter of 1mm was used to detect photoacoustic signals.