3-D shape and contrast reconstruction in optical tomography with level sets

Many applications of optical tomography in medical diagnostics, including the imaging of haematoma and tumours or the localisation of organs marked by a contrast agent, require the detection and localisation of well-defined boundaries between a homogeneous or weakly varying background and inclusions of different optical parameters. Shape-based reconstruction techniques, such as level sets, are better suited to solve these problems than conventional voxel-based approaches, which often lead to blurring of the boundaries of features and loss of contrast. In this paper we present a level set technique for the simultaneous recovery of absorption and diffusion distributions in a three-dimensional scattering medium. Images reconstructed from simulated frequency-domain boundary measurements are compared to a voxel-based conjugate gradient method. The results demonstrate the feasibility of the level set method.