To practice the ALARA principle which of the following techniques should you employ?

• A. Always use the least amount of Receiver gain that allows adequate tissue visualization.
• B. Adjust the controls so that the MI and TI readouts exceed 1.
• C. Use the lowest transmit power that allows adequate tissue visualization.
• D. Use the highest frame averaging setting.

Answer: (C)

ALARA in ultrasound means using only the energy necessary to obtain a diagnostic image. The best way to do this is to run with the lowest transmit power that still provides adequate tissue visualization. Lowering the transmit power reduces the energy deposited in tissue and lowers potential bioeffects, as long as the image remains sufficient for diagnosis. Other knobs, like receiver gain, only change how bright the image appears on the screen and do not change the energy delivered to tissue, so they aren’t the primary tool for ALARA. Monitoring safety indices like MI and TI is important, but aiming to exceed their recommended thresholds isn’t aligned with ALARA. Frame averaging affects image appearance but not the actual energy delivered, so it doesn’t replace lowering transmit power.