ARDMS Ultrasound Physics & Instrumentation Practice Exam

What is defined as the number of ultrasound pulses emitted in one second?

1. Pulse frequency

2. Pulse repetition frequency

3. Duty cycle

4. Pulse duration

The correct answer is: Pulse repetition frequency

The concept of pulse repetition frequency is essential in ultrasound physics as it defines how many ultrasound pulses are emitted by the transducer in one second. This is a crucial factor because it directly affects the temporal resolution of the ultrasound imaging. A higher pulse repetition frequency indicates that more pulses are being sent out per second, which can improve the ability to capture rapid movements or changes in the anatomy being examined. In the context of ultrasound, pulse repetition frequency is influenced by both the depth of imaging and the speed of sound in the medium. The need for more pulses at greater depths requires the system to manage the timing of these emissions carefully to avoid overlapping and to maintain image quality. Other terms like pulse frequency refer to the individual cycles within a pulse rather than the rate of pulse emission, while the duty cycle describes the proportion of time that the ultrasound system is actively emitting pulses as compared to the time it is listening for echoes. Pulse duration refers specifically to the length of time a single pulse is emitted. Therefore, pulse repetition frequency is the most fitting term to describe the number of packets of sound waves that are sent out every second.