Characteristic analysis of light and heat transfer in photothermal therapy using multiple-light-source heating strategy

Nanoparticles enhanced laser-induced thermal therapy (LITT) is an emerging method for early stage tumor treatment. One of the major issues challenging this technique is the accurate heating of the cancerous tissue without influencing the nearby healthy tissue. Owning to its outstanding optical, chemical, and biological properties, gold nanoparticles (GNPs) have been frequently applied to act as nanosource of heat for selective heating of tumor. In the present work, we studied the GNPs enhanced LITT theoretically. The bioheat transfer model under laser irradiation was established by the finite element method. The influences of laser intensity, GNPs volume fraction, anisotropic scattering characteristics of nanoparticles, convective heat transfer coefficient, and laser incident angle were investigated, respectively. On this basis, different treatment strategies, i.e. single heat source and multiple heat sources, were also explored. It is found that for single dose therapy, i.e. the whole tumor was damaged in one-time treatment, the efficacy is almost the same for oblique and vertical laser incident. However, for fractionated therapy, i.e. the tumor was totally damage after a series of treatments, the efficacy of oblique laser irradiation is better than that of vertical laser irradiation. Furthermore, the hyperthermia efficacy of multiple heat sources is much better than that of single heat source, which means that it can be applied in GNPs enhanced LITT to improve the photothermal therapy efficacy.