Publication Details
Abstract
The application of Low Level Laser Therapy (LLLT) has been under scientific scrutiny on various fronts, including the need for more knowledge about its thermal effects on biological tissues. Two advanced digital temperature measurement systems are implemented to evaluate temperature temporal and spatial profiles in biological tissues thus enabling an approximate assessment of thermal effects. Temperature profiles obtained with a Laser Doppler Vibrometer (LDV) for a tissue model subjected to continuous wave (cw) laser irradiation at 810 and 980 nm wavelengths, measured during both exposure and free time, showed a linear dependence of the maximum temperature rise as well as the heating and cooling times on the spatial average irradiance. The corresponding temperature rise values were also found to be independent of the tissue model (in vitro/in vivo). Moreover, pointwise measurements using an infrared thermometer positioned at different distances from the irradiated site on painted versus unpainted tissue showed significant contrasts, corroborating that a pig skin model (in vivo) and an apple model (in vitro) painted with white gouache, can be regarded as suitable tissue analogs for LLLT.