During obstetrical ultrasound, which parameter would increase acoustic exposure?

During obstetrical ultrasound, which parameter would increase acoustic exposure?

• A. Increase TGC
• B. Increase frequency
• C. Increase gain
• D. Increase transmit power

Answer: (D)

Acoustic exposure comes from the energy the transducer actually sends into the tissue. The key factor that determines how much energy enters the patient is the emitted beam’s power. When you increase transmit power, each ultrasound pulse carries more energy, so there is more energy deposited in the tissue per unit area and per unit time, raising the potential for heating and other effects. The other controls affect the image but not the emitted energy. TGC and gain modify how strong the received signal appears on the display; they adjust brightness after the echoes return, not the energy sent into the body. Frequency changes influence resolution and how quickly the beam is attenuated with depth, but at a fixed transmit power the total energy delivered to tissue isn’t increased in the same direct way as by raising transmit power. So, the factor that increases acoustic exposure is increasing transmit power.

Acoustic exposure comes from the energy the transducer actually sends into the tissue. The key factor that determines how much energy enters the patient is the emitted beam’s power. When you increase transmit power, each ultrasound pulse carries more energy, so there is more energy deposited in the tissue per unit area and per unit time, raising the potential for heating and other effects.

The other controls affect the image but not the emitted energy. TGC and gain modify how strong the received signal appears on the display; they adjust brightness after the echoes return, not the energy sent into the body. Frequency changes influence resolution and how quickly the beam is attenuated with depth, but at a fixed transmit power the total energy delivered to tissue isn’t increased in the same direct way as by raising transmit power.

So, the factor that increases acoustic exposure is increasing transmit power.