Which of the following lists the three types of ultrasound reflections described?

• A. Specular reflection; Scattering or backscattering reflection; Rayleigh reflection
• B. Specular reflection; Diffuse reflection; Rayleigh reflection
• C. Specular reflection; Scattering or backscattering reflection; Rayleigh reflection
• D. Specular reflection; Refraction; Diffraction

Answer: (C)

In diagnostic ultrasound, the three fundamental types of reflections described are specular reflection, scattering or backscattering reflection, and Rayleigh reflection.

Specular reflection happens at smooth, large interfaces (like vessel walls or organ boundaries) where the angle of incidence equals the angle of reflection. This produces clear, well-defined echoes and is what lets you see distinct borders on the image.

Scattering or backscattering reflection arises from rough, inhomogeneous tissue where the ultrasound wave is dispersed in many directions and a portion returns to the transducer. This creates a granular or speckled appearance and carries information about tissue microstructure.

Rayleigh reflection occurs when the scatterers are much smaller than the wavelength (for example, red blood cells). The energy is scattered more isotropically, contributing to weaker, diffuse backscatter signals from tiny particles within the blood or tissue.

Options that include refraction or diffraction mix different wave behaviors (bending of waves rather than pure reflection), and one term like diffuse reflection is another way to describe scattering but isn’t the specific trio described in this context.