Correlation between the Predicted Stress Field and Observed Spall-Failure in Artificial Kidney Stones Treated by Shock Wave Lithotripsy (SWL) in Vitro

摘要

We attempted to predict the failure of kidney stones due to the direct stress field of the lithotripter shock wave (SW). Numerical simulations of the acoustic field inside stones were carried out with a finite-difference time-domain (FDTD) code in a two-dimensional geometry. The code could model arbitrary shaped interfaces between the fluid and stone. Predictions from the code indicated that the peak tensile stress inside the stone was highly sensitive to the geometry of the distal surface of the stone; in particular curved surfaces produced a strong focusing effect. Focusing was weak for stones less than 3 mm in diameter.