Development of Numerical Simulator for Extracorpreal Shock Wave Lithotripsy System Using Numerical Phantom

1995 Fiscal Year Final Research Report Summary

• Project/Area Number: 06650284
• Research Category: Grant-in-Aid for General Scientific Research (C)
• Allocation Type: Single-year Grants
• Research Field: Dynamics/Control
• Research Institution: Okayama University
• Principal Investigator: TSUCHIYA Takao Okayama University, Department of Electrical and Electronic Engineering, Lecturer, 工学部, 講師 (20217334)
• Co-Investigator(Kenkyū-buntansha): HIROSE Souichi Okayama University, Department of Environmental and Civil Engineering, Associate, 環境理工学部, 助教授 (00156712) ; KAGAWA Yukio Okayama University, Department of Electrical and Electronic Engineering, Profess, 工学部, 教授 (10019200)
• Project Period (FY): 1994 – 1995
• Keywords: Finite Element Method / Sock Wave / Numerical Phantom / Electormagnetic Induction Transducer / Extracorpreal Shock Wave Lithotripsy / Focusing Sound

Research Abstract

A numercal simulator for extracorpreal shock wave lithotripsy is developed using the finite element method. The simulator consists of two part : one is the simulator for the electromagnetic induction transducer and another is for the nonlinear sound propagation. The simulator for the electromagnetic induction transducer can analyze the transient response including sound radiation. The formulation is made for coupled magneto-mechano-acoustic system using the axisymmetric finite element method in space, then the solution is made in time domain. Some numerical examples are demonstrated for a circular plate rediator and a shallow spherical shell radiator which has a better focusing capability. Experimental verification is then made for the fabricated models of small scale. The comparison proves the validity and the capability of the present numerical modeling.
The numerical simulator for the nonlinear sound propagation can analyze the sound propagation in inhomogeneous acoustic media such as human body. The human body is numerically modeled on computer using two dimensional finite element method and the model is called 'numerical phantom'. Numerical examples are then demonstrated for some numerical phantoms including the lithiasis. The following could be deduced from the analysis : 1) When the lithiasis is located at the focal point of the shock wave lithotriptor, the high destruct capability can be achieved and the tissue surround the lithiasis is kept the safety from the high intense shock wave because the shock wave is well scattered and diffracted by the lithiasis. 2) When the lithiasis is located at out of focus, the destruct capability is degraded and the normal tissue at the focal position is injured by the shock wave which penetrates the lithiasis.