Answer #13

The correct answer is E: intensity. Intensity is a better indicator of bioeffects than power (Choice B) or amplitude (Choice A)., Remember than power is proportional to amplitude^2 and is a better measure of bioeffects than amplitude alone.

Intensity is defined as power/beam area and measured in Watts/cm^2. A higher intensity ultrasound beam is more likely to increase the risk of bioeffects. Beam area is therefore not correct either (Choice C) and is inversely proportional to intensity and therefore the risk of bioeffects. Frequency is not directly related to bioeffects so choice E is correct.