Temporal backward projection of optoacoustic pressure transients using Fourier transform methods

In medical imaging different techniques have been developed to gain information from inside a tissue. Optoacoustics is a method to generate tomography pictures of tissue using Q-switched laser pulses. Due to thermal and pressure confinement, a short light pulse generates a pressure distribution inside tissue, which mirrors absorbing structures and can be measured outside the tissue. Using a temporal back-projection method, the pressure distribution measured on the tissue surface allows us to gain a tomography picture of the absorbing structures inside tissue. This study presents a novel computational algorithm, which, at least in principle, yields an exact reconstruction of the absorbing structures in three-dimensional space inside the tissue. The reconstruction is based on 2D pressure distributions captured outside at different delay times. The algorithm is tested in a simulation and back-projection of pressure transients of a small absorber and a single point source.