Ultrasonic imaging using optoelectronic transmitters

Conventional ultrasound scanners utilize electronic transmitters and receivers at the scanner with a separate coaxial cable connected to each transducer element in the handle. 2-D arrays which allow new imaging modalities to be introduced significantly increase the channel count and degrade the handling ability of the transducer cable assembly. Fiber optics which is a medium used to transmit signals optically has distinct advantages over standard coaxial cable to increase flexibility and decrease the weight of the transducer cable for large channel numbers. In transmit, optoelectronics would have to be designed to produce high voltage wide bandwidth pulses across the transducer element. In this paper, we describe a 48 channel ultrasound system having 16 optoelectronic transmitters and 32 conventional electronic receivers. A silicon avalanche photodiode (APD) and GaAs photoconductive switch (PCSS) were investigated for producing the transmit pulse. A Siemens SI-1200 scanner and a 2.25 MHz linear array were used to compare the optoelectronic system to the conventional electronic system. Transmit signal results and images in phantoms of cysts and tumors are provided for comparison.