The amount of ultrasound energy absorbed by tissue primarily depends on which tissue characteristic?

The amount of ultrasound energy absorbed by tissue primarily depends on which tissue characteristic?

• A. Protein content of tissues
• B. Water content
• C. Bone density
• D. Fat content

Answer: (A)

When ultrasound travels through tissue, the amount of energy it loses (and thus how much heating occurs) depends on how the tissue’s molecules interact with the sound wave. Proteins, especially collagen, are very effective at absorbing ultrasonic energy at therapeutic frequencies because of their molecular structure and dipolar properties. Tissues with higher protein content, such as connective tissues rich in collagen, therefore convert more of the ultrasound energy into heat per unit length than tissues with less protein. Water content also influences absorption, but across soft tissues protein content is the stronger predictor of how much energy is absorbed. Fat generally absorbs less, and bone causes substantial attenuation mainly due to its density and impedance, not the soft-tissue protein content.

When ultrasound travels through tissue, the amount of energy it loses (and thus how much heating occurs) depends on how the tissue’s molecules interact with the sound wave. Proteins, especially collagen, are very effective at absorbing ultrasonic energy at therapeutic frequencies because of their molecular structure and dipolar properties. Tissues with higher protein content, such as connective tissues rich in collagen, therefore convert more of the ultrasound energy into heat per unit length than tissues with less protein. Water content also influences absorption, but across soft tissues protein content is the stronger predictor of how much energy is absorbed. Fat generally absorbs less, and bone causes substantial attenuation mainly due to its density and impedance, not the soft-tissue protein content.