Comparison of the depth sensitivity functions sAC (z, ρ, ω), sPH (z, ρ, ω), and sDC (z, ρ) obtained with the DE. The results pertain to a slab 100 mm thick, ρ =20 mm,
, μa =0.005 mm−1, ν = {100, 200, 400} MHz and refractive indexes of slab and external, 1.4 and 1, respectively.