Owed to wide use of pulsed lasers in a medical field, a deep understanding of
their effects on the temperature increase in tissue and the subsequent tissue thermal
damage in a coagulation process may be a matter of importance. The influence of
laser beam profile, repetition rate and pulse width on temperature distribution and the
subsequent thermal damage in tissue are studied using finite element method, which
solves the axis-symmetry bio-heat equation in tissue subjected to far IR pulse laser
irradiation. Some conclusions are obtained: as energy/pulse remains constant,
Gaussian laser beam profile rather than a top-hat beam will increase the in-depth
tissue thermal damage at and near the center of the spot region, increasing in
repetition rate will increase the temperature distribution and subsequent damage zone.
As pulse width decrease, high temperature may be reached leading to cause a
quantitatively and qualitatively damage which can be recognize as an increase in the
size of the damage zone and a higher value of thermal dose. An increase in pulse
width will reduce the rate at which energy deposed in the tissue which result in low
extent of temperature increase which result in reduction of the damage zone
quantitatively and qualitatively.