In depth calibration testing with a phantom, depth accuracy is most influenced by which property pair?

In depth calibration testing with a phantom, depth accuracy is most influenced by which property pair?

• A. Reflector spacing and reflection coefficient
• B. Attenuation of sound speed in the medium
• C. Reflector spacing and ultrasound attenuation in the medium
• D. Reflector spacing and propagation speed

Answer: (D)

Depth accuracy comes from how precisely the time it takes for echoes to return can be converted into distance. In a phantom with known reflector spacings, you have fixed reference distances to compare against the measured times. The key conversion is distance = (speed of sound × round-trip time) / 2. So knowing the propagation speed of the medium and having accurate, known reflector spacings together determine how accurately you can map time to depth. If the speed is off, all depth readings shift; if the reflector spacings aren’t known precisely, the reference for checking depth accuracy is wrong. Attenuation or reflection coefficients mainly affect signal strength and echo visibility, not the timing used for depth calculation, so they don’t drive depth accuracy as directly.

Depth accuracy comes from how precisely the time it takes for echoes to return can be converted into distance. In a phantom with known reflector spacings, you have fixed reference distances to compare against the measured times. The key conversion is distance = (speed of sound × round-trip time) / 2. So knowing the propagation speed of the medium and having accurate, known reflector spacings together determine how accurately you can map time to depth. If the speed is off, all depth readings shift; if the reflector spacings aren’t known precisely, the reference for checking depth accuracy is wrong. Attenuation or reflection coefficients mainly affect signal strength and echo visibility, not the timing used for depth calculation, so they don’t drive depth accuracy as directly.