Quantitative Photoacoustic Imaging of The Distribution of The Optical Properties in Biological Medium

Wideband ultrasonic waves (referred to as photoacoustic waves) are induced as a result of transient thermoelastic expansion of biological tissues irradiated by a laser light. The magnitude of the photoacoustic (PA) waves is proportional to the local optical-energy deposition; hence, the waves divulge physiologically specific optical absorption contrasts. For visualizing the internal structure, PA image reconstruction which is a mathematical process with use of photoacoustic pressure is employed. Since image reconstruction has a fundamental impact on the image quality, various algorithms have been proposed. In this review article, we summarize reports regarding image reconstruction algorithms and introduce our approaches for the quantitative image reconstruction.