Complications due to extracorporeal shock wave lithotripsy and role of cavitation bubbles impacts

This paper presents a study of the role played by cavitations´ bubbles in the creation of side effects or complications of cavitation bubbles´ impact generated by Extracorporeal Shock Wave Lithotripsy (ESWL). Apart from many useful applications of shock waves therapy, specifically, key role of cavitations´ bubbles in the disintegration of urinary calculi, there is a large number of complications due to improper cavitations´ bubbles intensity applied on the surfaces or organs. For the best result of ESWL with the lowest complications, shock wave intensity should be selected and controlled accurately. The main purpose of this study was to determine the impulse of a bubble on a surface. To do this, the results of previous numerical studies were used to derive a relationship between the speed of microjet and acoustic pressure amplitude. It was found that the speed of microjet is proportional to the logarithm of the acoustic pressure amplitude. Aluminum foil specimens were exposed to cavitation for seconds and the dimensions of permanent pits generated on specimens were measured. Then, the deformation energy of each pit and the corresponding impulse were calculated. The trend of experimental results was in a good agreement with the theoretical ones.