Effective radiating area refers to what?

Effective radiating area refers to what?

• A. Area of sound head
• B. Frequency of the wave
• C. Size of crystal in machine
• D. Depth of tissue penetration

Answer: (A)

Effective radiating area is the portion of the ultrasound transducer that actually emits energy into the tissue—the active emitting surface of the sound head. This area matters because the tissue intensity is calculated as power divided by ERA, so a smaller emitting area gives higher intensity at the same power, while a larger area yields lower intensity. The other options point to factors that influence how energy behaves (frequency affecting depth, crystal size related to potential output, penetration depth), but they don’t define what ERA is.

Effective radiating area is the portion of the ultrasound transducer that actually emits energy into the tissue—the active emitting surface of the sound head. This area matters because the tissue intensity is calculated as power divided by ERA, so a smaller emitting area gives higher intensity at the same power, while a larger area yields lower intensity. The other options point to factors that influence how energy behaves (frequency affecting depth, crystal size related to potential output, penetration depth), but they don’t define what ERA is.