Abstract

Bringing laser-induced thermal therapy to gastroenterology and accepting it as a traditional method continues to be an essential topic of discussion. This discussion highlights coagulation parameters such as laser power, surface scanning speed, beam diameter, and irradiation duration. In addition, the parameters form a large matrix that must be optimized for successful treatment, including minimal damage to surrounding tissues. In this study, we aimed to propose a guide map representing the results of a simulation algorithm developed to provide information about the coagulation parameters of laser-induced thermal therapy of esophageal mucosal tissue. The simulation algorithm is based on the Monte-Carlo method for light transport in tissue, the time-dependent finite difference method for heat transfer, and the Arrhenius damage integral. This study includes validation experiments performed in ex vivo sheep esophagus, including histological analysis, light microscopy imaging, and block-face scanning electron microscopy investigations. The laser wavelength used in the studies is 1.5 µm, providing an optical penetration depth of around 0.5 mm in soft tissue, while the diameter of the laser beam on the tissue surface is 0.9 mm. The simulation algorithm evaluated the photothermal coagulation area in a tissue model with a volume of 4 x 4 x 4 mm³ for laser power up to 0.5 W and a surface scanning speed range of 0.5 mm/sec to 8 mm/sec. Direct comparison of simulation results with ex vivo studies showed significant overlap in laser energy per unit area for successful mucosal coagulation. The findings suggest that the proposed simulation approach can serve as a complementary guide tool for laser-induced photothermal therapy for superficial treatments and as a ground algorithm for future preclinical and clinical trials.

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