Pass-through photon-based biomedical transillumination

Assessing Absorption Coefficient of Hemoglobin in the Breast Phantom Using Near-Infrared Spectroscopy

BACKGROUND

Blood concentrations and oxygen saturation levels are important biomarkers for breast cancer diagnosis.

OBJECTIVES

In this study, the absorption coefficient of hemoglobin (Hb) was used to distinguish between normal and abnormal breast tissue.

MATERIALS AND METHODS

A near-infrared source (637 nm) was transmitted from major and minor vessels of a breast phantom containing 2×, 4× concentrations of oxy- and deoxy-Hb. The absorption coefficients were determined from spectrometer (SM) and powermeter (PM) data.

RESULTS

The absorption coefficients were 0.075 ± 0.026 cm^-1 for oxygenated Hb (normal) in major vessels and 0.141 ± 0.023 cm^-1 at 4× concentration (abnormal) with SM, whereas the breast absorption coefficients were 0.099 ± 0.017 cm^-1 for oxygenated Hb (normal) in minor vessels and 0.171 ± 0.005 cm^-1 at 4× concentrations with SM. A comparison of the data obtained using a SM and a PM was not significant statistically.

CONCLUSION

The study of the absorption coefficient data of different concentrations of Hb in normal and abnormal breasts via the diffusion of near-infrared light is a valuable method and has the potential to aid in early detection of breast abnormalities with SM and PM in major and minor vessels.

Forward-calculated analytical interferograms in pass-through photon-based biomedical transillumination

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.