In typical clinical imaging, ultrasound power ranges from which values?

• A. 0.40 to 9.0 watts
• B. 0.004 to 0.090 watts
• C. 0.0004 to 0.009 watts
• D. 0.04 to 0.9 watts

Answer: (B)

In diagnostic ultrasound, the energy delivered to tissue is kept very low to minimize any potential bioeffects, so the power used for typical imaging is in the milliwatt range. The imaging system delivers short pulses with a low duty cycle, so the instantaneous power can be higher, but the average exposure remains small. That’s why the commonly cited range for ultrasound power in routine clinical imaging is about 0.004 to 0.090 watts (roughly 4 to 90 milliwatts). Values much lower would struggle to produce usable images, while values much higher would push the exposure toward safety limits and aren’t standard for everyday imaging.