Diagnostics of Layer-by-Layer Biotissue Evaporation in the Process of Two-Coordinate Scanning by a Laser Beam for Precision Surgery

The use of automated and robotic systems for precision low-traumatic surgery is a common trend in modern medicine. One of the promising tools for such operations is an automated laser scalpel based on a scanner with real-time diagnostics of the process of biotissue evaporation. The paper investigates the possibility of operational Doppler diagnostics of layer-by-layer laser evaporation of biomodels. A surgical CO 2 laser with a two-coordinate scanning system was used as a scalpel. The method of autodyne detection of backscattered radiation coming from the laser action zone was used to diagnose the evaporation process. Samples based on Difco agar with different water content and various tissues of pigs in vitro were used as biomodels. The depth of evaporation, the zone of thermal damage of the samples, and the dynamics of the autodyne signal were studied depending on the scanning modes and parameters of laser radiation. It has been shown that the autodyne signal arising from the layer-by-layer evaporation of samples is sensitive to the water content of biomodels and the structural features of the tissue. Autodyne diagnostics of layer-by-layer laser scanning makes it possible to control the evaporation process of biotissue of the same type and to determine the boundaries between tissues of different types both in the scanning plane and in the tissue depth. The obtained results can be used in the developing technologies for automated laser layer-by-layer evaporation of biological tissues in relation to the precision low-traumatic surgery tasks.