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An attempt to reconstruct the lithotriptor shock wave pulse in kidney: possible temperature effects
L Filipczyński1, J Etienne, M Piechocki
1Department of Ultrasonics, Polish Academy of Sciences, Warsaw.
Ultrasound in Medicine & Biology
|January 1, 1992
Summary
Shock wave pulses used in lithotripsy decrease in amplitude and steepness when penetrating the kidney. This study numerically reconstructs these altered pulses, finding significant reductions relevant for kidney stone treatment.
Area of Science:
- Biomedical Engineering
- Acoustic Physics
- Medical Imaging
Background:
- Extracorporeal shock wave lithotripsy (ESWL) uses shock waves to break kidney stones.
- Understanding shock wave propagation through biological tissues is crucial for optimizing ESWL effectiveness and safety.
- Previous studies often simplify tissue interactions, necessitating more accurate modeling.
Purpose of the Study:
- To numerically reconstruct the amplitude and shape of shock wave pulses as they penetrate kidney tissue.
- To analyze the differences between shock waves in water and those reaching kidney stones.
- To investigate the impact of tissue properties on shock wave parameters and temperature elevation.
Main Methods:
- Numerical reconstruction of shock wave pulses based on in-vitro measurements in water using two lithotripsy systems.
- Experimental validation of the differences between shock waves in water and those propagating through tissue.
- Analysis of shock wave absorption and attenuation in tissues, considering amplitude-dependent nonlinear effects.
- Estimation of temperature elevation within tissues due to shock wave interaction.
Main Results:
- Shock wave pulse amplitude and front steepness decrease significantly within kidney tissue compared to water.
- For a 4 cm distance, shock wave amplitude reduces by approximately 50%, and front steepness decreases severalfold.
- Tissue absorption and attenuation increase with shock wave amplitude, limiting temperature elevation.
- Maximum estimated temperature elevation is 1.8 times that calculated with linear absorption models.
Conclusions:
- Kidney tissue significantly alters shock wave characteristics, reducing their amplitude and steepness.
- Nonlinear absorption and increased attenuation in tissues play a critical role in moderating shock wave energy deposition.
- Accurate modeling of these effects is essential for predicting lithotripsy outcomes and patient safety.