PAM Ultrasound & Phonophoresis 2

Question 1

Which tissue type has the highest ultrasound absorption coefficient?

Accepted Answer

Cortical bone

Answer

Cortical bone has the highest absorption coefficient because its density and protein content cause maximal attenuation of ultrasound energy.

Question 2

When using ultrasound over a superficial metal implant, the clinician should:

Accepted Answer

Avoid the area entirely due to risk of overheating

Answer

Metal implants can reflect and concentrate ultrasound energy, creating dangerous hot spots; the area should be avoided.

Question 3

The term 'cavitation' in therapeutic ultrasound refers to:

Accepted Answer

Formation and oscillation of gas bubbles in tissue fluids

Answer

Cavitation involves the formation and oscillation (stable) or collapse (unstable) of gas-filled bubbles in biological fluids exposed to ultrasound.

Question 4

For phonophoresis to be effective, the drug vehicle (gel/cream) must:

Accepted Answer

Be acoustically transparent and allow US transmission

Answer

The coupling medium must be acoustically transparent so ultrasound energy is not absorbed by the vehicle before reaching the target tissue.

Question 5

A 1-MHz ultrasound unit will penetrate to approximately what tissue depth?

Accepted Answer

2–5 cm

Answer

1-MHz ultrasound penetrates to approximately 2–5 cm, making it suitable for deeper structures than the 3-MHz frequency.

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