To measure penetration on a tissue-mimicking phantom, how should the master gain and acoustic output be adjusted?

• A. Minimum gain, maximum acoustic output
• B. Maximum gain, maximum acoustic output
• C. Maximum gain, minimum acoustic output
• D. Minimum gain, minimum acoustic output

Answer: (B)

Penetration into a tissue-mimicking phantom is limited by attenuation, so deeper echoes become weaker as depth increases. To reliably detect those deeper signals, you need both more transmitted energy and greater receiver sensitivity. Increasing the acoustic output raises the transmitted power, helping the ultrasound reach deeper regions, while increasing the master gain boosts the amplification of the echoes that return from those depths. Together, they maximize the likelihood of observing echoes from deeper structures, which is essential for measuring penetration. If either parameter is reduced, deep echoes may be lost in noise or fail to be detected, making penetration assessment unreliable.