Background: One of the current shortcomings of radiofrequency (RF) tumor ablation is its limited performance in regions close to large blood vessels, resulting in high recurrence rates at these locations. Computer models have been used to determine tissue temperatures during tumor ablation procedures. To simulate large vessels, either constant wall temperature or constant convective heat transfer coefficient (h) have been assumed at the vessel surface to simulate convection. However, the actual distribution of the temperature on the vessel wall is non-uniform and time-varying, and this feature makes the convective coefficient variable.

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ABSTRACT:The interchain and interactions of two parallel chains are studied numerically through the dynamics of charged polaron and bipolaron in the presence of an electric field by using the Pariser-Parr-Pople model combined with the Su-Schrieffer-Heeger model. The electron-lattice coupling and the Brazovskii-Kirovatype symmetry-breaking interaction are introduced in the current model. The electric field is introduced in terms of a time-dependent vector potential that is included in the Hamiltonian through a Peierls substitution of the phase factor to the transfer integral. The charge-transfer probability between charged polarons and bipolarons belonging to neighboring chains is determined by the numerical resolution of the equations of motion within the unrestricted Hartree-Fock approximation. The effects of confinement on the polaron and bipolaron motion are determined.

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Several studies have been conducted on the applicability of hyperthermia radiofrequency in the treatment of liver tumors. Many theoretical studies have reported the relevance of various physical parameters in terms of their efficacy in combating tumors and have analyzed the impact of these physical parameters on the temperature profile in the diseased tissue. Parameters such as thermal and electrical conductivities have been investigated during simulations of thermal ablation. Such parameters play an important role in the process of heat transfer in tissues. The purpose of this study is to predict the lesion volume, considering the inclusion of temperature dependence of thermal-electrical properties. This paper introduces a three-dimensional computational model that includes different comparative combinations of tissue thermal-electrical parameters as a mapping of temperature (such as thermal and electrical conductivities and specific heat). The finite-element method is employed for simulating hepatic radiofrequency ablation through the numerical solutions of the bioheat, Laplace, and Navier–Stokes equations. The results suggest that different combinations of tissue temperature-dependent parameters can significantly affect the computed lesion volume and that the temperature dependence of electrical conductivity has a major impact on the computed lesion volume and temperature distribution.