Optical Coherence Tomography in Biophotonics

Biophotonics is an exciting frontier which focuses on the interaction between light and biological matter thereby fusing photonics and biology. The use of photonics for light-activated and light-guided therapy as well as optical diagnosis promises to have major impact on fundamental biological science as well as life sciences and health care. In general, biophotonics integrates four major technology platforms: lasers, photonics, nanotechnology and biotechnology. These technologies have already established themselves in research and industry. Biophotonics offers tremendous opportunities for both basic research and technology development by fusion of the above mentioned areas. Many light-based and spectroscopic techniques are already being used as optical probes in clinical laboratories as well as in medical and other health-care practices. Photonics based/optical imaging techniques such as conventional microscopy as well as confocal, fluorescence and multi-photon microscopy enable high axial and transverse ( 1 mm) resolution imaging, but have limited penetration in biological tissue. An imaging modality that enables non-invasive, simultaneous imaging of both three-dimensional cellular resolution tissue morphology and also assessment of depth resolved function with sufficient depth penetration and imaging contrast could significantly improve early medical diagnosis, contribute to a better understanding of disease pathogenesis and enhance the monitoring of therapy. Optical coherence tomography (OCT) is a rapidly emerging non-invasive, imaging modality enabling in vivo cross-sectional tomographic visualization of internal microstructure in biological systems at resolution levels of a few micrometers that offers great hope for significantly improved early disease detection [1, 2]. Novel high speed detection techniques as well as development of ultrabroad bandwidth and tuneable light sources have recently revolutionized imaging performance and clinical feasibility of OCT. In this view OCT can now be considered as an optical analogue to computed tomography and magnetic resonance imaging, not enabling full body imaging, but non-invasive optical biopsy, i.e. micron/cellular resolution three-dimensional visualization of tissue morphology. In addition, extensions of OCT have been developed that enable non-invasive depth resolved functional imaging, providing spectroscopic, blood flow, polarization sensitive or physiologic tissue information. These extensions of OCT should not only improve image contrast, but should also enable the differentiation of pathologies via localized metabolic properties or functional state [2]. OCT was initially demonstrated for retinal imaging and followed a unique path to commercialization for clinical use. According to ‘Optical Coherence Tomography – Technology, Markets, and Applications: 2008–2012’, a new market research report from the publisher of BioOptics World that quantifies this rapidly growing market for the first time, the global market for OCT systems is currently around $ 200 million and growing at an annual rate of 34%. This growth is expected to continue at this pace for the next several years, with revenues topping $ 800 million by 2012. The clinical impact of OCT, especially in ophthalmology, is also demonstrated by the fact that several fourth generation of commercial instruments have recently been introduced and that, world-wide, there are more than one half dozen companies commercializing this technology for ophthalmic diagnosis. Presently, at least 20 companies are actively developing and/or manufacturing OCT systems, with many more supplying the key technological components, e.g. optical sources, detectors, and related photonics components that enable the various OCT products and applications resulting in a total of more than 50 companies. As this technology continues to penetrate new mar-