The safety principle used to minimize biological effects in humans and the fetus is known as?

• A. ALARA
• B. LIFELINE
• C. SAFE-GUARD
• D. MIN-EX

Answer: (A)

ALARA stands for As Low As Reasonably Achievable. In ultrasound, this principle means we minimize the amount of acoustic energy delivered to tissues while still obtaining the information we need. Although diagnostic ultrasound uses nonionizing energy, there can be thermal and mechanical effects at higher output, so we aim to keep exposure as low as possible.

Practically, this means using the lowest acoustic power and the shortest scan time that still yield a diagnostic image. It involves optimizing settings—depth, gain, focus, and transducer choice—to avoid cranking up output. When Doppler is used, limit the duration and intensity, especially in obstetric exams. Monitoring indicators like thermal index and mechanical index helps guide power decisions, and if those indices rise toward limits, we reduce output or unnecessary scanning. The overall goal is to obtain the needed diagnostic information with the minimum exposure, protecting both the patient and the fetus.

The other terms listed aren’t standard safety principles in ultrasound practice, so they don’t guide clinical decisions in the same way ALARA does.