TIME-RESOLVED IMAGING OF SOLID PHANTOMS FOR OPTICAL MAMMOGRAPHY

We have recorded time-resolved transillumination images of solid phant oms with objects embedded that differ in their scattering and absorpti on coefficients from those of the bulk material, simulating a compress ed human breast with a tumor inside. Employing time-correlated single photon counting at rates of up to 1 MHz, we recorded distributions of times of flight of photons at 1369 scan positions within 2.5 min. Seve ral quantities, such as fractional transmittance, first moments, Fouri er amplitudes, phase shifts, and frequency-dependent effective transpo rt scattering and absorption coefficients, have been derived from expe rimental data to form two-dimensional images. By recording such images at a selected total number of photons detected, we have determined th e contrast and effective signal-to-noise ratio in each case. (C) 1997 Optical Society of America