Valerii A. Ulyanov

Determination of biotissue type in the course of CO2 laser ablation using backscattered radiation

The correlation between Doppler spectra due the emission of tissue destruction products at laser ablation and tissue types was established. The possibility of biotissue type relative determination at the passage of CO2 laser beam through various sequences of tissue layers is demonstrated.

The lasers for TMLR application

The paper presents the analysis of the requirements to the laser systems used to cure the ischemic disease of the heart by the method of transmyocardial laser revascularization (TMLR). Among the medical laser systems under discussion (solid-state Nd:YAG, Er:YAG, Ho:YAG, excimer lasers, etc.) the high-power CO2 laser with pulse energy to 40 J is most suited to produce channels in the heart muscle. The paper provides the description and the technical characteristics of medical laser systems of “Perfocor” series, based on high-power waveguide CO2 lasers with pulse energy to 60 J, developed at ILIT RAS. The methods to determine the time of laser radiation penetration through the myocardium/blood boundary have been briefly discussed. The application of the “Perfocor” system in other laser operations on blood-filled organs has also been discussed.

Monitoring of laser ablation of biotissues on backscattered radiation

The monitoring system for laser vaporization of biotissues based on autodyne detection method of backscattered radiation with the help of high-frequency pumping CO2 laser was developed. It was shown that this method gives the possibility to determine the instant of laser beam passage through tissue layers boundary in real-time. The magnitudes of integrated intensity of power spectrum (UPS) and weighted mean frequency of Doppler signal spectrum (v) were used for the characterization of Doppler signal in time of laser pulse. As an example the dependencies of IIPS(t) and v(t) for different sets of tissue layers are presented. The stick-slip change of these magnitudes near tissue layers boundary is the base of feed-back for irradiation stopping and change of laser radiation parameters

Diagnostics of CO2 laser ablation of biotissues by autodyne detection method of backscattered radiation

CO2 laser-tissue interaction was investigated by the autodyne detection method of backscattered radiation. Doppler spectra obtained in the course of pulse ablation of various pig tissues in vitro are presented. The interrelation between these spectra and some properties of biotissues was established. The possibility of the instants of time determination of the laser radiation passage through the demarcation line of biotissues is demonstrated.