Optimisation of Laser Parameters for Treatment of Basal Cell Carcinoma

Abstract

In this study a model is proposed to estimate and optimise the exposure durations of laser beams of different powers for superficial Basal Cell Carcinomas of varying radii and depth. The frequent application of Laser in medical field makes it a matter of significance, to study the distribution of temperature in tissue, its effects on tumourous tissue and the extent of thermal damage in healthy tissue during photo-thermal therapy. The tissue temperature is numerically estimated by solving Penne’s bioheat equation for 2-D multilayered skin model using Finite Volume Method and the conversion of laser light inside the tissue is expressed by Beer-Lambert’s Law. This study focuses on Basal Cell Carcinoma (BCC) which is a semi-malignant tumour of the skin that derives from incompletely differentiated immature keratinocytes of the epidermis. In this paper, different sizes of Basal Cell Carcinoma are considered which are irradiated by continuous wave Nd:YAG laser with Gaussian beam profile. The spatial and temporal thermal damage to the tissue is estimated by using the Henriques’ theory of skin burns which uses Arrhenius equation. A hitherto unused grid-based model is employed to depict the penetration of the damage front viewed against the tumour-tissue interface. This study attempts to propose a correlation between optimised exposure time and laser power for a particular tumour radius. An inverse proportional relation between laser power and irradiation time, for a particular tumour radius, was quantitatively established in this study.