Background and Aim: Liposuction is one of the most popular procedures for removing unwanted body fat deposits now. The conventional methods for liposuction however have many drawbacks; among them is long recovery time, scars, bruising, skin flaccidity and excessive blood loss. Considering the increasing demand for body sculpting, the need to improve these techniques is of vital importance. One of these newly proposed techniques is laser assisted lipolysis. Laser lipolysis is now widely used for body contouring and sculpting. Less trauma, bleeding and pain is among the main advantages of this method.

Methods: Photons propagation and scattering within the biological tissues can effectively investigated by using numerical methods. In this study we used the Monte Carlo simulation method to simulate photons directions, absorption and scattering inside the tissue. This method uses a random number generator for photons creation, moving inside the tissue and termination. In this simulation we considered both the wavelength and fluence variations effects on the photon absorption rate and penetration depth inside the fat tissue.

Results: Our study showed the increasing of penetration depth with decreasing of absorption coefficient. We observed that deepest penetration depth for 920 nm wavelength as it has lowest absorption coefficient. We also concluded that increasing the laser power (increase in fluence of laser) resulted in increasing the penetration depth of laser radiation. Increasing the radius of laser beam (decreasing the fluence) on the other hand resulted in reduction in penetration depth.

Conclusion: Monte Carlo simulation of radiation propagation within the biological tissue has proved to be an efficient method. This method effectively simulates the physical components of laser radiation. Our findings indicate that to have laser lipolysis more efficient and safe, it is essential to choose suitable wavelength.