Development of flexible acoustic transmission line for intravascular ultrasonography

A fused quartz rod coated with a thin film of carbon was prepared and tested for ultrasound transmission. The rod was 125 μm in diameter and 60 cm long. Both ends of the rod were polished. A PZT transducer was attached at one end, and the other end was kept open. An electrical burst wave with a frequency of between 3 and 30 MHz was applied to the transducer, which generated a correspond ultrasonic signal, and the received signal was observed. It was shown that the L(0,1) mode of the Pochhammer-Chree wave propagated in the 125 μm diameter test rod in the frequency range 3-24 MHz. A large dispersion was observed in the frequency range 20-24 MHz. The attenuation constant of the line was estimated to be less than 1 dB/m at 8 MHz. A coil with a diameter of 3 cm was made using the rod, and the same experiment was conducted. The experimental results were similar to that for the straight rod