Sub-surface Diffuse Fluorescence Tomography: System Development and Feasibility Studies

Sub-surface tomography with diffuse light has been investigated with a non-contact approach to characterize the performance of optical absorption and fluorescence imaging. Using both simulations and experimental studies, the reconstructed images of local sub-surface heterogeneities was demonstrated, using diffusion properties characteristic of near-infrared light in mammalian tissue. The results indicate that the recovery of target size and fluorophore concentration is not linear when changes in depth occur, whereas the mean position of the object for experimental fluorescent and absorber targets is accurate to approximately 1mm when located within the first 10 mm below the surface. Improvements in the linearity of the response with depth appear to remain challenging and may ultimately limit this tomographic imaging approach to detection rather than characterization applications. However, increases in tissue curvature and/or the addition of prior information are expected to improve the linearity of the response. The potential for this type of imaging technique to serve as a surgical guide is highlighted.