Application of infrared imaging for non-contact measurements of thermal diffusivity in tissue

We demonstrate application of an infrared (IR) imaging technique for non-contact determination of thermal diffusivity of biological materials. The IR method utilizes pulsed laser excitation to produce an initial three-dimensional temperature distribution in tissue, and records IR images of subsequent heat diffusion. The theoretical model assumes the time-dependent temperature increase following pulsed laser exposure occurs due to independent heat diffusion in longitudinal and lateral directions. A nonlinear least-squares algorithm is used to compute the lateral point spread function from a pair of recorded IR images and determine thermal diffusivity of a test specimen. Application of the method was demonstrated using tissue phantoms and ex-vivo samples of hydrated cartilage.