Whole Field Reflectance Optical Tomography

CARBONE, NICOLÁS; GARCÍA, HÉCTOR; DI ROCCO, H. O.; IRIARTE, D. I.; POMARICO, J. A.; RANEA SANDOVAL, H. F.

Puebla

Congreso; 22nd Congress of the International Commission for Optics: Light for the Development of the World; 2011

Optical imaging through highly scattering media such as biological tissues is a topic of intense research, especially forbiomedical applications. Diverse optical systems are currently under study and development for displaying the functionalimaging of the brain and for the detection of breast tumors. From the theoretical point of view, a suitable description oflight propagation in tissues involves the Radiative Transfer Equation, which considers the energetic aspects of lightpropagation. However, this equation cannot be solved analytically in a closed form and the Diffusion Approximation isnormally used. Experimentally it is possible to use Transmission or Reflection geometries and Time Resolved,Frequency Modulated or CW sources. Each configuration has specific advantages and drawbacks, depending on thedesired application. In the present contribution, we investigate the reflected light images registered by a CCD camerawhen scattering and absorbing inhomogeneities are located at different depths inside turbid media. This configuration isof particular interest for the detection and optical characterization of changes in blood flow in organs, as well as for thedetection and characterization of inclusions in those cases for which the transmission slab geometry is not well suited.Images are properly normalized to the background intensity and allow analyzing relative large areas (typically 5 x 5 cm 2 )of the tissue. We tested the proposal using Numerical Monte Carlo simulations implemented in a Graphic ProcessingUnit (Video accelerating Card). Calculations are thus several orders of magnitude faster than those run in CPU.Experimental results in phantoms are also given.