<title>Reconstruction of embedded absorbers in random media with applications in noninvasive 3D imaging of skin lesions</title>

Abstract

An optical backscatter measuring instrument called a Nevoscope is being developed to non-invasively determine 3D characteristics of skin lesions with applications in the diagnosis of malignant melanoma. Optical images are obtained by transilluminating the lesion and imaging backscattered radiation emanating from the skin surface. Such emission profiles contain information about the absorption characteristics of sub-surface structures. It is conceivable that such profiles can be used to reconstruct structural information of inhomogeneities such as a mole embedded in the skin. Monte Carlo simulations of photon migration are performed to simulate the radiation pattern of backscattered radiation imaged at the surface of the medium when a light source is placed directly on the surface of the medium. In particular, simulations are performed on media with single embedded absorbers. This is the simplest model of a mole embedded in human skin. Some reconstruction algorithms based on the difference in emission profiles in the presence and absence of the absorber, are tested. A prototype Nevoscope presently being used for visual examination is described. Heuristic reconstruction schemes using images obtained from the Nevoscope are also presented.

<title>Genetic-algorithm-based reconstruction in diffusion tomography</title>

“…Our application of diffusion tomography, which has been described in recent papers [19,25], restricts our measurements to back-scatter measurements only. In these initial experiments, however, we consider the flux distribution within the medium as the available data.…”

“…Monte carlo simulation of particle transport is a conceptually simple method of studying light propagation and is enjoying increasing popularity amongst researchers in tissue-optics [14, 15,16,17,18]. The monte carlo method is versatile in simulating physical experimental setups and is being used by the authors in the development of an imaging instrument for dermatological applications [19,20]. Unfortunately, a large number of photon histories have to be simulated to obtain data with acceptable variance.…”