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.