Limiting the size of the treatment area in ultrasound therapy causes the waves to do what?

Limiting the size of the treatment area in ultrasound therapy causes the waves to do what?

• A. Spread out and not penetrate
• B. Concentrate energy and penetrate deeper
• C. Increase absorption in tissue
• D. Remain unchanged in behavior

Answer: (A)

When you shrink the area being treated, you’re effectively using a smaller aperture for the ultrasound beam. A smaller aperture causes more diffraction, so the wavefront spreads as it propagates. That spread means the energy becomes less concentrated and the intensity at depth drops, so the waves don’t penetrate as deeply. Concentrating energy and reaching deeper tissues would require maintaining or increasing focus, not limiting the area. The beam won’t stay unchanged because changing the treatment size changes the beam geometry and how energy is delivered into tissue.

When you shrink the area being treated, you’re effectively using a smaller aperture for the ultrasound beam. A smaller aperture causes more diffraction, so the wavefront spreads as it propagates. That spread means the energy becomes less concentrated and the intensity at depth drops, so the waves don’t penetrate as deeply. Concentrating energy and reaching deeper tissues would require maintaining or increasing focus, not limiting the area. The beam won’t stay unchanged because changing the treatment size changes the beam geometry and how energy is delivered into tissue.