Study Of Reconstruction Techniques For Optical Tomography

As a novel imaging modality for medical purpose, optical tomography (OT) has received much attention in recent years. In this imaging modality, the near-infrared light is used to irradiate the subject, and after which the image corresponding to the optical parameters can be obtained for the subject to be imaged. Owing to the fact that the aforementioned optical parameters are directly related to such functional information as the blood volume and the blood oxygenation saturation status of the subject, the optical tomography is a functional imaging modality. As compared to other imaging modalities such as the X-ray computed tomography, the superiorities of this imaging modality lie in its low instrumentation costs, and also lie in the fact that it is radiative harmless as well as it can be employed for the purpose of long time monitoring of the patients.In experimental systems, light is guided by optical fibers to the surface of the subject and detecting fibers are used to measure the transilluminated light. Thus the inverse problem is one of the recoveries of coefficients in a domain from data on its boundary and its transport model in tissue.At present, most of the reconstruction algorithms of the optical tomography are based on the diffusion approximation of the transport model, and very few researchers have devoted themselves to the study of reconstruction algorithms directly based on the transport equation. On the other hand, the diffusion equation is not valid for the case when the absorption coefficients are not much smaller than the scattering coefficients or for the case when both the scattering and the absorption coefficients are very low (both cases play important role in the biomedical applications) , and, as a result, the image can not be reconstructed based on the diffusion equation in those cases. Hence, the goal of this thesis will be focused on the study of the reconstruction algorithms based on the transport equation. Contributions of this thesis are summarized as follows:...