Laser irradiation of ferrous particles for hyperthermia as cancer therapy, a theoretical study

Thermal field and tissue damage analysis of moving laser in cancer thermal therapy

In this paper, a closed-form analytical solution of hyperbolic Pennes bioheat equation is obtained for spatial evolution of temperature distributions during moving laser thermotherapy of the skin and kidney tissues. The three-dimensional cubic homogeneous perfused biological tissue is adopted as a media and the Gaussian distributed function in surface and exponentially distributed in depth is used for modeling of laser moving heat source. The solution procedure is Eigen value method which leads to a closed form solution. The effect of moving velocity, perfusion rate, laser intensity, absorption and scattering coefficients, and thermal relaxation time on temperature profiles and tissue thermal damage are investigated. Results are illustrated that the moving velocity and the perfusion rate of the tissues are the main important parameters in produced temperatures under moving heat source. The higher perfusion rate of kidney compared with skin may lead to lower induced temperature amplitude in moving path of laser due to the convective role of the perfusion term. Furthermore, the analytical solution can be a powerful tool for analysis and optimization of practical treatment in the clinical setting and laser procedure therapeutic applications and can be used for verification of other numerical heating models.

Effect of size, concentration, and type of spherical gold nanoparticles on heat evolution following laser irradiation using tissue-simulating phantoms

Photothermal therapy has recently gained a considerable attention particularly after the revolution of nanomaterials and nanotechnology. The aim of the present study is to assess the optimal photothermal response through investigating some effective parameters of spherical gold nanoparticles (AuNPs), e.g., type, size, and concentration, as a preclinical study for efficient photothermal treatment. Tissue-simulating phantoms based on agar and water media incorporated with two different types of AuNPs, spherical Au particles capped with citrate or spherical Au core-silica shell NPs, were built. Heat evolution for each NP type was recorded in the phantom matrix with different particle sizes at various concentrations following exposure to low laser power (irradiance 35 mW/cm(2)) and emitting at λ = 532 nm. Our results demonstrated that AuNPs capped with citrate recorded higher temperature elevations than those capped with silica shell. Particles with smaller sizes produced more heating effect than those having larger sizes. Also, higher temperatures were recorded at a critical concentration of NPs. Exponential decay constants based on theoretical calculations demonstrated that laser attenuation increases with the continuous increase of particle size and concentration.