Which control most closely affects patient exposure during an abdominal ultrasound study?

Which control most closely affects patient exposure during an abdominal ultrasound study?

• A. Receiver overall gain
• B. TGC
• C. Dynamic range
• D. Output power

Answer: (D)

The key idea is that patient exposure comes from the acoustic energy the transducer sends into the body. The control that directly governs that energy is the transmit output power, which sets the intensity of the ultrasound beam entering tissues. Increasing this power raises the energy deposited in the tissue, boosting exposure. Receiver gain, TGC, and dynamic range all affect how the returned echoes are processed or displayed, not the energy that leaves the transducer. Receiver gain amplifies signals after they’re received, TGC adjusts amplification with depth on the return signal, and dynamic range alters image contrast. None of these change how much energy is transmitted or deposited in the patient, so they don’t affect exposure the way transmit output power does. Keeping output power as low as diagnostically necessary aligns with ALARA principles.

The key idea is that patient exposure comes from the acoustic energy the transducer sends into the body. The control that directly governs that energy is the transmit output power, which sets the intensity of the ultrasound beam entering tissues. Increasing this power raises the energy deposited in the tissue, boosting exposure.

Receiver gain, TGC, and dynamic range all affect how the returned echoes are processed or displayed, not the energy that leaves the transducer. Receiver gain amplifies signals after they’re received, TGC adjusts amplification with depth on the return signal, and dynamic range alters image contrast. None of these change how much energy is transmitted or deposited in the patient, so they don’t affect exposure the way transmit output power does. Keeping output power as low as diagnostically necessary aligns with ALARA principles.