Attenuation of Ultrasound Ultrasound is absorbed in the body; this complicates th...

Attenuation of Ultrasound

Ultrasound is absorbed in the body; this complicates the use of ultrasound to image tissues. The intensity of a beam of ultrasound decreases by a factor of 2 after traveling a distance of 40 wavelengths. Each additional travel of 40 wavelengths results in a decrease by another factor of 2.

A physician is making an image with ultrasound of initial intensity 1000 W/m 2 . When the frequency is set to 1.0 MHz, the intensity drops to 500 W/m 2 at a certain depth in the patient’s body. What will be the intensity at this depth if the physician changes the frequency to 2.0 MHz?