ARDMS Ultrasound Physics & Instrumentation Practice Exam

Which term is defined as only the active time during ultrasound?

1. Pulse duration

2. Frequency

3. Pulse repetition frequency

4. Wavelength

The correct answer is: Pulse duration

The term defined as only the active time during ultrasound is pulse duration. Pulse duration refers specifically to the time period that an ultrasound pulse is generated, encapsulating the duration from the start of the pulse until the end of that pulse. This measurement is crucial because it affects the axial resolution of the ultrasound images; shorter pulse durations lead to better resolution and clarity, allowing for more detailed imaging of structures. In contrast, frequency refers to the number of cycles of the ultrasound wave that occur in one second, which influences penetration and image resolution but does not denote active time. Pulse repetition frequency indicates how many pulses are sent out in one second, focusing on the rate of pulse transmission rather than the active time of each pulse. Wavelength is associated with the distance between successive peaks of the wave and is influenced by both frequency and speed of sound in the medium, but it does not pertain to the active time of ultrasound emission. Understanding pulse duration is essential for optimizing ultrasound imaging techniques and outcomes.