Frequency-domain diffuse optical tomography with single source-detector pair for breast cancer detection

An experimental setup for multicolor frequency-domain diffuse optical tomography (FD DOT) was created to visualize neoplasia of breast tissue and to estimate its size. The breast is gently pressed between two glass plates and scanned in the transilluminative configuration by a single source and detector pair. Illumination at three wavelengths (684 nm, 794 nm, and 850 nm) which correspond to different parts of the absorption spectrum in a therapeutic transparency window provides information about concentration of the main absorbers (oxygenated hemoglobin, deoxygenated hemoglobin, and fat/water). Source amplitude modulation at 140 MHz increases spatial resolution and provides separate reconstruction of scattering and absorption coefficients. Moreover, it gives information about breast thickness, which is important for reconstruction. The sensitivity of the system enables one to detect the light propagated through tissue having thickness up to 8 cm. Studies on model media and preliminary in vivo experiments with normal breast and breast carcinoma were performed. An increase of scattering coefficient and total hemoglobin concentration is observed in the tumor area. This corroborates validity of the FD DOT method for breast cancer diagnosis.