Temperature measurement on tissue surface during laser irradiation

Tissue surface temperature distribution on the treatment site can serve as an indicator for the effectiveness of a photothermal therapy. In this study, both infrared thermography and theoretical simulation were used to determine the surface temperature distribution during laser irradiation of both gel phantom and animal tumors. Selective photothermal interaction was attempted by using intratumoral indocyanine green enhancement and irradiation via a near-infrared laser. An immunoadjuvant was also used to enhance immunological responses during tumor treatment. Monte Carlo method for tissue absorption of light and finite difference method for heat diffusion in tissue were used to simulate the temperature distribution during the selective laser photothermal interaction. An infrared camera was used to capture the thermal images during the laser treatment and the surface temperature was determined. Our findings show that the theoretical and experimental results are in good agreement and that the surface temperature of irradiated tissue can be controlled with appropriate dye and adjuvant enhancement. These results can be used to control the laser tumor treatment parameters and to optimize the treatment outcome. More importantly, when used with immunotherapy as a precursor of immunological responses, the selective photothermal treatment can be guided by the tissue temperature profiles both in the tumor and on the surface.