Simulation of circular array ultrasound transducers for intravascular applications

The beam shape of a circular array transducer that is commonly used in intr avascular ultrasound catheters was investigated in linear mode of operation . For this use, a simulation program which can simulate the radio frequency (rf)-response of a number of scatterers has been developed. The program is based on the impulse response method, which is implemented in the frequenc y domain, Due to the unusual geometry of the transducer, the far field gets peculiarly shaped for large apertures, instead of having a far field with its maximum intensity in a single lobe on the acoustical axis, the far fiel d splits up into a dual-lobe far held with maximum intensity in two lobes o ff the acoustical axis. A formula is derived that predicts the occurrence o f these beam shapes. (C) 2000 Acoustical Society of America. [S0001-4966(00 )00108-9].