Pass-through photon-based biomedical transillumination.

We present the mathematical foundation and the experimental validation of a technique that utilizes pass-through (ballistic) photons in a partial coherence interferometric transillumination setup for biomedical analyses. We demonstrate that the implementation depends closely on tissue under test, incident power, spatial and spectral characteristics of the radiation source, and detection electronics. With the aid of the complex material coherence function concept, we foresee tissue characterization and diagnostic imaging as potential applications for the technique. We propose a normalization procedure for in vitro and in vivo measurements, where nontissue-related quantities are canceled out. The validation of the proposal is achieved by obtaining the sample coherence function of a tissue phantom. The expected exponential attenuation is confirmed, and the corresponding scattering coefficients are determined. A good agreement between theory and experiment, for the initial set of samples, serves to establish that pass-through photon-based transillumination is feasible for selected biomedical applications.