A new photoacoustic method for measuring optical transport Green´s functions in turbid media

Photoacoustic imaging has shown great promise as a hybrid imaging technique offering optical contrast and ultrasonic spatial resolution. The optical contrast in photoacoustic images is primarily due to optical absorption rather than optical scattering, yet optical scattering is a tissue parameter of key importance. Here a new photoacoustic method for estimating the optical scattering properties of tissues is presented. The technique is based on the idea that the ultrasonic focal region of a transducer is an effective virtual detector of relative laser fluence, and translocation of light relative to the fixed ultrasound focus will provide an effective measure of the Green´s function of radiative light transport in tissues. A novel light delivery probe was created and tested to prove the concept of the idea.