Computational study of photo-thermal ablation of large blood vessel embedded tumor using localized injection of gold nanoshells.

Attaining a precise necrosis of tumor sparing normal tissue during carcinomas thermo-therapy via nominally invasive scheme like irradiation of laser is a recent challenge. In this study, a combined diffusion and convective energy equations were solved using COMSOL Multiphysics to predict the tissue thermal profile during laser assisted thermo-therapy with different tissue vascular networks. A comparative analysis between intratumoral and intravenous loading scheme of silica-gold nanoshells (AuNs) was also performed. AuNs cluster position and alignment was altered to achieve precise ablation of a large tumor with minimum damage to healthy tissue and improvement in necrosis in the vicinity of large blood vessels (LBV). A modified Beer-Lambert law and Arrhenius equation was applied to model laser heat propagation and to compute thermal damage respectively. Simulation results suggests the dominance of targeted nanostructure injection in cluster form over intravenous scheme in terms of precise control over spreading of necrotic zone due to selective laser dose delivery into the tumor. An effective tumor ablation, sparing normal tissue is best revealed for Type-A intratumoral scheme comparing Type-B and C as the reallocation of cluster position can help to achieve an irregular shaped necrotic zone. In addition a comparative analysis between dual-phase-lag (DPL) and classical Fourier approach within a tumor-blood inhomogeneous inner structure was made to access the effect of relaxation time onto biological thermal response. Numerical results show a difference in temperature profile between these two approaches during non-equilibrium condition i.e at the prior phases of laser heating and cooling whereas the results overlaps at higher instants. Since the DPL based bioheat conduction model can predict the inherent wave nature of the thermal front which is propagating at a finite speed. This study may improve the real clinical invasive schemes applied to ablate malignant tumor during hyperthermia treatment.