Medical engineers are developing a new ultrasound probe for high-resolution liver imaging. The speed of longitudinal sound waves in liver tissue can be taken as v=1.55×103ms−1. To resolve small internal features, the design team specifies that the acoustic wavelength in the tissue must not exceed 0.50mm. The probe is intended to operate in pulsed mode so that echoes from successive pulses do not overlap.
(a) Calculate the minimum frequency the ultrasound transducer must generate so that the wavelength in liver tissue is no larger than the value specified above. Give your answer in megahertz (MHz).
(b) Determine the period of one oscillation of this ultrasound wave.
(c) Current electronics in the facility are limited to a maximum operating frequency of 5.0MHz. Evaluate whether this equipment can achieve the required imaging resolution, supporting your answer with a quantitative comparison.
(d) Briefly explain, without additional calculation, why increasing the operating frequency beyond your answer to part (a) would improve the image’s spatial resolution yet could reduce the maximum imaging depth inside the body.