What is the unit for pressure amplitude in ultrasound?

The unit for pressure amplitude in ultrasound is Pascals. Pressure amplitude refers to the maximum pressure variation from the average pressure within a sound wave. When ultrasound waves travel through a medium, they create fluctuations in pressure relative to the ambient pressure in that medium. The Pascal is the SI unit of pressure, defined as one Newton per square meter, and is commonly used in various scientific fields, including acoustics and ultrasound imaging, to quantify these pressure changes in a sound wave.

The other options are used in different contexts: Watts measure power, Decibels quantify intensity levels on a logarithmic scale, and Millimeters are a unit of length, which is not applicable to pressure measurements in ultrasound. Understanding these distinctions helps clarify the specific context in which each unit is properly used.