A Review of Laser Technology and Light-Tissue Interactions as a Background to Therapeutic Applications of Low Intensity Lasers and Other Light Sources

Abstract

This paper reviews aspects of laser physics, radiometry and photochemistry relevant to the use of low intensity light therapy delivered by lasers or conventional lamps. Current theories regarding the biophysical mechanisms of low intensity laser therapy are reviewed. Characteristics of laser radiation such as monochromaticity, coherence, collimation, speckle, beam profile, penetration depth and temporal modulation of irradiation, and the relevance of these factors to photon propagation are explained. Physical principles that describe light–tissue interactions are presented. The importance of irradiance and radiant exposure is discussed and methods of quantifying these values are shown. Clinical implications are briefly discussed.