摘要

Advances in the area of opto-electronics which allow the detection of low intensity light have increased interest in the study of light propagation in turbid media. One of the most exciting applications of these emerging technologies is the use of near infrared spectroscopy and imaging in medicine. Since the absorption of photons by biological tissues is low in the 700-900 nm spectral region, it is feasible to use near infrared radiation as a medical probe. Few advancements have had a greater impact on medical science than the development of techniques to noninvasively determine the internal structure of biological tissues. Many view the development of near infrared spectroscopy and imaging techniques as the next important step in the continued improvement of this vital area of medical science. The use of near infrared radiation has two primary advantages over the use of x-rays. The first advantage is that near infrared light is non-ionizing, so it is safer than x-rays. The second advantage is that the near infrared absorption spectra of biological tissue depends on the functional status of the tissue, so near infrared spectroscopy and imaging can provide functional as well as structural information. However, unlike x-rays, near infrared radiation is highly scattered by biological tissues. Therefore, image reconstruction and spectroscopic techniques capable of extracting useful information from multiply scattered light are necessary. This paper describes some techniques that are being developed to measure the optical properties and to obtain images of biological tissues from an analysis of multiply scattered radiation.