Transillumination of breast phantoms using diffuse photon density waves

Diffuse Photon Density Waves (DPDWs) characterise photon migration through diffusive media in the frequency-domain. Theoretically, we describe DPDWs propagation using the diffraction theory based on the diffusion approximation to the transport equation. Experimentally, we study the propagation of 100 MHz-modulated DPDWs through (optical)-breast-like phantoms. The great interest of probing these phantoms lies in the fact that they contain very small optical inhomogeneities, with a diameter of 5 mm only and with inhomogeneity/background absorption and scattering contrasts of 1.1, 1.5, 2.0 and 4.0 respectively. We show that both most contrasted inhomogeneities (in absorption and scattering) can be distinguished, while the 1.5 contrasted one is visible only in scattering. This is consistent with the measured actual accuracy of our set-up which is 0.3% in amplitude and 0.15 degrees in phase. Experimental results are compared to simulations, time-domain experimental results and X-ray measurements.