What term denotes the concentration of mass, weight, or matter per unit volume?

What term denotes the concentration of mass, weight, or matter per unit volume?

• A. Amplitude
• B. Density
• C. Frequency
• D. Half value layer

Answer: (B)

Density is the measure of how much matter is packed into a given volume, i.e., mass per unit volume. In ultrasound, density (together with the tissue’s stiffness) helps determine acoustic impedance (Z = ρc), which influences how much sound is reflected at boundaries and how fast it travels through tissue. This concept is different from amplitude (the strength of the sound wave), frequency (how many cycles per second), and half value layer (a radiation-physics term used for attenuation in X-ray science, not ultrasound).

Density is the measure of how much matter is packed into a given volume, i.e., mass per unit volume. In ultrasound, density (together with the tissue’s stiffness) helps determine acoustic impedance (Z = ρc), which influences how much sound is reflected at boundaries and how fast it travels through tissue. This concept is different from amplitude (the strength of the sound wave), frequency (how many cycles per second), and half value layer (a radiation-physics term used for attenuation in X-ray science, not ultrasound).