Spatially variant regularization improves diffuse optical tomography

Diffuse tomography with near-infrared light has biomedical application for imaging hemoglobin, water, Lipids, cytochromes, or exogenous contrast agent s and is being investigated for breast cancer diagnosis. A Newton-Raphson i nversion algorithm is used for image reconstruction of tissue optical absor ption and transport scattering coefficients from frequency-domain measureme nts of modulated phase shift and light intensity. A variant of Tikhonov reg ularization is examined in which radial variation is allowed in the value o f the regularization parameter. This method minimizes high-frequency noise in the reconstructed image near the source-detector locations and can produ ce constant image resolution and contrast across the image field. (C) 1999 Optical Society of America OCIS codes: 110.6960, 110.7050, 170.6960, 170.70 50.