Image quality in time-resolved laser transillumination by time-correlated single photon counting

The intrinsic quality of an image is related to the concepts of spatial resolution, noise and contrast. A common method to measure these parameters is by using Edge Response Function measurements with a black mask. We investigated these parameters using an experimental apparatus mainly composed by a an argon pumped Ti:Sa laser working in femtosecond regime and a time-correlated single photon-counting system. The investigated samples were suspensions of Intralipid 10% with distilled water in which a black mask was inserted and bidimensional scanning were performed at different depths (z = L/2, L/4, 3L/4). The experimental data were analyzed in order to get information on the above-mentioned image quality parameters. A comparison with similar results obtained with a streak camera has been done and for spatial resolution a comparison with random walk predictions has been performed. The results of this study can be particularly useful in identifying the best working conditions and in improving the performance of image reconstruction algorithms since the clinical prototypes of optical mammographers nowadays under pre-clinical investigation adopt time-correlated single photon-counting technique.