OPTICAL-IMAGE RECONSTRUCTION USING DC DATA - SIMULATIONS AND EXPERIMENTS

In this paper, we explore optical image formation using a diffusion ap proximation of light propagation in tissue which is modelled with a fi nite-element method for optically heterogeneous media. We demonstrate successful image reconstruction based on absolute experimental DC data obtained with a continuous wave 633 nm He-Ne laser system and a 751 n m diode laser system in laboratory phantoms having two optically disti nct regions. The experimental systems used exploit a tomographic type of data collection scheme that provides information from which a spati ally variable optical property map is deduced. Reconstruction of scatt ering coefficient only and simultaneous reconstruction of both scatter ing and absorption profiles in tissue-like phantoms are obtained from measured and simulated data. Images with different contrast levels bet ween the heterogeneity and the background are also reported and the re sults show that although it is possible to obtain qualitative visual i nformation on the location and size of a heterogeneity, it may not be possible to quantitatively resolve contrast levels or optical properti es using reconstructions from DC data only. Sensitivity of image recon struction to noise in the measurement data is investigated through sim ulations. The application of boundary constraints has also been addres sed.