An FDTD-based computer simulation platform for shock wave propagation in electrohydraulic lithotripsy
Özet
Extracorporeal Shock Wave Lithotripsy (ESWL) is based on disintegration of the kidney stone
by delivering high-energy shock waves that are created outside the body and transmitted
through the skin and body tissues. Nowadays high-energy shock waves are also used in
orthopedic operations and investigated to be used in the treatment of myocardial infarction
and cancer. Because of these new application areas novel lithotriptor designs are needed
for different kinds of treatment strategies. In this study our aim was to develop a versatile
computer simulation environment which would give the device designers working on various medical applications that use shock wave principle a substantial amount of flexibility
while testing the effects of new parameters such as reflector size, material properties of
the medium, water temperature, and different clinical scenarios. For this purpose, we created a finite-difference time-domain (FDTD)-based computational model in which most of
the physical system parameters were defined as an input and/or as a variable in the simulations. We constructed a realistic computational model of a commercial electrohydraulic
lithotriptor and optimized our simulation program using the results that were obtained by
the manufacturer in an experimental setup. We, then, compared the simulation results with
the results from an experimental setup in which oxygen level in water was varied. Finally, we
studied the effects of changing the input parameters like ellipsoid size and material,temperature change in the wave propagation media, and shock wave source point misalignment.
The simulation results were consistent with the experimental results and expected effects
of variation in physical parameters of the system. The results of this study encourage further investigation and provide adequate evidence that the numerical modeling of a shock
wave therapy system is feasible and can provide a practical means to test novel ideas in new
device design procedures.
