RESUMO
Recently, we have introduced a transillumination technique for biomedical diagnosis. The technique, pass-through photon-based transillumination, relies on interferometric measurements to recover the information of interest. In this work, we present the forward-calculated analytical interferograms that describe the behavior of the system. Stochastic modeling of radiation interacting with tissue enables determination of amplitude and phase parameters, indispensable for computation of the interferograms. Sample variability is assessed by studying tissue phantoms similar to those used in the experimental verification of the technique and that are representative of (abnormal) dental tissues. For tissue characterization, perfect recovery of the integrated attenuation ensues by employing spatially compact radiation sources. For tissue imaging, spatially extended sources with broad bandwidth are superior due to the implicit longitudinal coherence filter. For both applications, sample variability issues may be neutralized by permitting spatial divergence of scattered photons.
Assuntos
Simulação por Computador , Processamento de Imagem Assistida por Computador , Modelos Teóricos , Fótons , Odontologia/métodos , Diagnóstico por Imagem , Humanos , Espalhamento de RadiaçãoRESUMO
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.