Background and Objective
Owing to the greater absorption affinity for lipo‐rich tissue than water, the 1210 nm laser is a promising candidate for transcutaneous lipolysis in the near‐infrared band. However, fat reduction is limited because laser therapy may yield thermal injury of normal tissue. A new protocol to incorporate multipulsed cryogen spray cooling is beneficial to improve the lipolysis effect, and the parameters of laser and cooling can be optimized via skin histopathological analysis.
Materials and Methods
A murine in vivo model of inguinal tissue of SD rats was established to test the effectivity of transcutaneous lipolysis protocol by R134a multipulsed spray cooling assisted 1210 nm laser irradiation. Tissue response of lipolysis with/without cooling 10 days post the treatment was evaluated by histopathological analysis of skin samples stained with hematoxylin–eosin (HE), through which safe and effective parameters for lipolysis were determined.
Results
From histopathological analysis of the inguinal tissue of SD rats irradiated by the 1210 nm laser alone, the optimal durations are respectively 7 and 3 s (seconds) for low‐dosage (6 W) and high‐dosage (9 W) therapy, with pronounced lipolysis effect and minimum injury of skin tissue. The multipulsed spray cooling by R134a with a pulse duration of 10 ms (milliseconds), a pulse delay of 2000 ms, and a pulse number of 5 can be introduced to assist the 1210 nm laser therapy with a power of 9 W and a duration of 7 s to achieve desirable fat liquefaction while keeping the complete structure of skin tissue as well as esthetic‐related beneficial effects of hair removal and skin rejuvenation.
Conclusion
Excellent lipolysis effect can be achieved via R134a multipulsed spray cooling assisted high‐dosage 1210 nm laser irradiation with reasonably matched laser and cooling parameters. The protocol is as follows: Start MP‐CSC for one cycle, and then fire the laser with specific power and duration, while keeping MP‐CSC accordingly. This new protocol may promote the safe and effective clinical implement of transcutaneous laser lipolysis in body contouring.
The paper analyzed the thermal problem of the 2D FGM beam using meshless weighted least-square (MWLS) method. The MWLS as a meshless method is fully independent of mesh, and an approximate function was used to construct a series of linear equations to solve the unknown field variable, which avoided the troublesome task of numerical integration. The effectiveness and accuracy of the approach were illustrated by a clamped-clamped FGM beam which was subjected with interior heat source. The volume fraction of FGM beam was assumed to be given by a simple power law distribution. The effective material properties of the FGM beam were assumed to be temperature independent and calculated by Mori-Tanaka method. The results showed that a good agreement was achieved between the proposed meshless method and commercial COMSOL Multiphysics.
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