Time-resolved transillumination for medical diagnostics

We demonstrate a time-gated technique to reduce the effect of light scattering when transilluminating turbid media such as tissue. The concept is based on transillumination with picosecond laser pulses and time-resolved detection. By detecting only the photons with the shortest travelling time, and thus the least scattered photons, the contrast can be enhanced. Measurements on a tissue phantom as well as breast tissue in vitro are presented. It is demonstrated that differences in scattering properties may be more pronounced than differences in absorption properties when demarcating tumor from normal tissue.