Study on Optimal Optical Parameters for Cutting Liver Tissue with a Novel 980/1470 nm Dual-Wavelength Semiconductor Laser.

PURPOSE: Laser-tissue interactions induce photothermal effects governed by wavelength-dependent absorption and circulation of energy. While 980 nm targets hemoglobin for hemostasis and 1470 nm targets water for vaporization, their synergistic optimization in living liver tissue remains undefined, as existing studies predominantly examine ex vivo models or single wavelengths. This study establishes quantitative relationships between laser parameters and tissue outcomes in an in vivo model.

METHODS

Twenty rabbits (female New Zealand White, 1.5-2 kg) underwent hepatic transection using a 400 μm bare fiber diameter (3 mm tissue distance, 10 mm/s advancement speed) in continuous-wave (CW) and pulsed-modulated (100 ms pulse, 50% duty cycle, 5 Hz) modes. Output power: 980 nm (12-160 W) and 1470 nm (6-48 W), with different dual-wavelength power ratios. Measured outcomes: cutting depth, vaporization depth, coagulation depth, and thermal injury depth (quantified by hematoxylin and eosin staining).

STATISTICS: analysis of variance for continuous variables, chi-square/Fisher's exact test for categorical variables, and the Mann-Whitney U test for non-normal distributions (p < 0.05).

RESULTS

CW mode achieved greater cutting depth than pulsed-modulated mode (median 943.97 μm vs. 689.43 μm, p < 0.05). In CW mode, 1470 nm-dominated ratios (0:1, 1:1, 1:2, 1:3, 1:4) achieved greater cutting depths than 980 nm alone (1:0). Cutting depth increased with peak power from 6 to 120 W, then decreased at 160 W due to carbonization. At 24 W total power with 1:2 ratio (8 W 980 nm/16 W 1470 nm), cutting depth was 1249.3 ± 15.55 μm, vaporization depth 739.5 ± 35.32 μm, coagulation depth 1302 ± 125.44 μm, and thermal damage 1987.53 ± 154.61 μm.

CONCLUSIONS

The 980/1470 nm wavelength power ratio of 8/16 W in CW mode for liver tissue cutting offers high efficiency, safety, and minimal thermal damage, providing an effective surgical energy device for minimally invasive and precise treatment.