Sonography Canada Physics Core Practice Exam

The correct choice focuses on pulse parameters that are influenced only by the sound source and are essential for understanding how ultrasound waves operate. Pulse duration refers to the time it takes for one pulse of sound to occur, and it is determined by the characteristics of the transducer. Since the transducer generates sound waves, factors such as the number of cycles in a pulse and the frequency directly influence pulse duration. Pulse repetition period (PRP) is the total time from the beginning of one pulse to the beginning of the next. It is determined by the sound source because the pulse duration and the listening time, which is also influenced by the source, dictate the overall PRP. Pulse repetition frequency (PRF) is defined as the number of pulses emitted per second. It is inversely related to the PRP and is entirely a function of the sound source, as it represents how often the source sends out pulses. Duty factor is the fraction of time that the ultrasound machine is actively transmitting sound compared to the total time (transmitting plus listening). It depends solely on the parameters set by the transducer itself, namely the pulse duration and PRP, making it another sound source-derived parameter. Together, pulse duration, PRP, PRF, and duty