Answer #30

The correct answer is C: The wavelength is determined only by the properties of the medium through which the ultrasound travels. Wavelength is actually determined by both the speed at which the ultrasound travels within the medium (c) as well as the frequency of transmission from the source. In fact c = f * wavelength.

All of the other choices are correct. The type of scattering at a surface depends on the wavelength (specular, Rayleigh scattering for example) so E is correct. The typical range for diagnostic ultrasound is 2 MHz to 20 MHz. This corresponds to wavelengths of 77-770 micrometers (assuming a speeds of 1540m/s in the medium) so B is correct. Axial resolution is in part defined by wavelength so choice A is correct. And choice D defines wavelength; it is a distance of one cycle which is from a peak to peak or from valley to valley.