A physician wishes to see the internal structure of the caro

A physician wishes to see the internal structure of the carotid arteries, located relatively superficially below the skin of the neck. Abdominal ultrasound imaging can be performed with ultrasound of frequency 3MHz, which allows imaging to a depth of somewhat over 10 cm. If similar conditions are used in imaging the carotid arteries, which of the following frequencies would be the most appropriate: (a) 1 MHz, (b) 5 MHz, (c) 10 MHz, (d) 15 MHz

Solution

Answer is (d) 15 MHz

Given,

frequency = 3MHz

depth = 10 cm

Higher frequencies are used to resolve the carotid arteries

Use a frequency that is 5 times higher , therefore

5 * frequency = 5*3 = 15 MHz

which corresponds to a wavelength of 0.1 mm

15 MHz would be the most appropriate