3 - Photon migration and imaging of biological tissues

Abstract

This chapter discusses photon migration and imaging of biological tissues. A lot of useful information can be obtained by using currently available techniques for imaging and monitoring living tissues. There is still a strong request for new techniques, possibly non-invasive. The chapter begins by introducing the optical parameters that are needed to characterize diffusing media and briefly describing theories and methods used to study photon migration through highly scattering media. This chapter explains the concept of the status of the tissue, such as the blood oxygen saturation, which can be obtained if the optical properties of the tissue can be properly measured. There is hence, a large potential for obtaining basic information on tissues by using non-ionizing radiation in the visible and near-infrared region of the electromagnetic spectrum, but there is little available on instrumentation based on light. The reason is that biological tissues are strongly scattering media and thus, measurements of optical properties are difficult. The chapter also discusses different techniques currently studied for imaging and monitoring biological tissues.