STUDIES OF ACOUSTICAL AND SHOCK-WAVES IN THE PULSED-LASER ABLATION OFBIOTISSUE

Quantitative studies are conducted into the absolute pressure values o f the acoustical and shock waves generated and propagating in a biotis sue under pulsed (tau(p) = 50 ns) UV (lambda = 308 nm) laser irradiati on (below and above the ablation threshold). Powerful (several hundred s of bars in pressure) high-frequency (f congruent-to 10(7) Hz) acoust ic compression and rarefaction pulses are found to be generated in the biotissue. The amplitudes and profiles of the acoustic pulses develop ing in atherosclerotic human aorta tissues and an aqueous CuCl2 soluti on under laser irradiation are investigated as a function of the laser pulse energy fluence. The results obtained point to the absence of th e cold spallation of the objects of study by rarefaction waves. Based on experimental data, the rise rates, pressure gradients, and propagat ion velocities of shock waves in the biotissue are calculated. The exp erimental data are found to agree well with the theoretical estimates. (C) 1993 Wiley-Liss, Inc.