Photoacoustic imaging of biological tissues with high cross-section resolution

A modified back-projection approach deduced from an exact reconstruction solution was applied to photoacoustic tomography of differential absorption in biological tissues. Pulses from an Nd:YAG laser (8 ns FWHM at 1064 nm) were employed to generate the distribution of acoustic sources in a sample. The acoustic signals were detected over a 2π angle in an imaging plane that was perpendicular to the laser axis by a wide-band cylindrically focused ultrasonic transducer. Samples were made from slabs of pork fat in which several high absorption objects made from pig blood were buried. The reconstructed images agreed very well with the pictures of the samples. By employing our detection system and a reconstruction algorithm, a satisfying cross-section resolution that is better than 0.1 mm was achieved.