Analysis of Laser-Fat Interaction Through Comparing 980 nm Diode Laser With 1064 nm Nd:YAG Laser

Liposuction nowadays is the most popular way of weight loss and body contouring. It is a mechanical procedure to reduce fat through the back-and-forth movement of a heavy metal called cannula. The thick cannula, essential for efficient fat removal and subsequent suctioning, causes some undesirable effects such as bruise, scars, heavy blood loss, skin laxity and long-run recovery. While, the new method of liposuction using a 100-300 µm fiber laser inserted into a thin cannula of 1 mm diameter causes less distress and bleeding. Simultaneous interaction between laser radiation and tissue causes faster skin tightening and coagulation of small blood vessels. The study aimed at evaluating the effects of these highly important parameters of lipolysis operations. In this study, penetration depth and tissue heating following laser irradiation with a 980 nm diode laser were investigated. This laser is different from 1064 nm Nd:YAG in terms of absorption and scattering coefficient. Hence, dissimilar results for beam penetration and tissue heating were expected. Monte Carlo method was used to simulate radiation (photons) propagation in tissues. Using such simulation can be useful in evaluating penetration depth, absorption, scattering and reflection of the photon within the tissue and across the tissue borders. Temperature rise was simulated using Comsol Multiphysics software. The simulation results showed that the penetration depth and temperature rise of 980 nm wavelengths were different from those of 1064 nm wavelength. It appeared that 1064 nm wavelength penetrated to deeper layers of tissue compared with 980 nm. Moreover, temperature rise during 1064 nm irradiation led to temperature increase in allowable ranges. The findings proved the reason why 1064 nm wavelength are commonly used in laser lipolysis in comparison with 980 nm wavelength. The simulation indicated that temperature rise in 980 nm wavelength was 70.802 ℃, which was higher than that of 1064 nm wavelength. Therefore, 980 nm laser can leave unwanted negative effects on tissues including hyperthermia.