Which operator control increases the acoustic exposure to the patient?

• A. Increased receiver amplification
• B. Increased time-gain compensation
• C. Decreased pulse repetition frequency
• D. Increased output gain

Answer: (D)

The correct answer is based on the understanding of how ultrasound systems operate and the effects of various controls on the acoustic output. Increasing the output gain directly amplifies the strength of the ultrasound signals produced by the transducer. This means that the intensity of the sound waves being sent into the patient is higher, which results in increased acoustic exposure.

Acoustic exposure refers to the total energy delivered to the tissues, which is influenced significantly by the output of the ultrasound. When the output gain is increased, more powerful sound waves are emitted, leading to a greater potential for tissue interaction and a higher level of acoustic energy being deposited within the patient's body.

In contrast, while increased receiver amplification can enhance the signal received and make it easier to visualize details, it does not affect the initial sound wave intensity from the transducer being directed into the tissue. Time-gain compensation helps to manage varying signal strengths across different depths but does not directly increase the acoustic exposure itself. A decreased pulse repetition frequency reduces the rate at which sound waves are emitted, thus decreasing overall acoustic exposure rather than increasing it.