Very high frequency (50 to 100 MHz) ultrasonic transducers for medical imaging applications

The performance of ultrasonic transducers which operate at frequencies greater than 20 MHz has attracted significant interest due to the wide range of applications which have been shown to benefit from the fine spatial resolution of the images which these systems are capable of generating. This work examines the properties of both commercial PZT materials, which typically have a grain size of approximately 2 to 5 ;Transducers designs are presented for PT transducers operating between 50 and 100 MHz. These designs are contrasted to PZT transducers and the differences which result in improved performance are emphasized. Actual transducers are constructed from the new PT materials and the measured properties are compared to those predicted from a one dimensional model. Images made with these transducers are shown, with references to the measured performance characteristics including the pulse echo waveform and the acoustic field.;The fine grain PZT material is shown to be useful for producing array elements with very small dimensions. Dicing experiments show that the fine grain materials withstand dicing much better than conventional materials with much larger grain sizes. Array designs at operating frequencies of 20 and 50 MHz are proposed with the new fine grain materials.