The number of images displayed per second in real-time imaging is termed the:

• A. Pulse Repetition Frequency
• B. Pulse Repetition Period
• C. Frame Rate
• D. Pulse Duration

Answer: (C)

The key idea is how many complete images the system can display each second in real-time imaging. That measure is the frame rate. Each frame is built from many scan lines, with the transducer emitting pulses and receiving echoes along each line. Because creating a frame requires multiple pulses across those lines, the speed of displaying frames (the frame rate) depends on how fast pulses can be fired and how many lines make up one frame. In other words, higher frame rates mean smoother motion because more frames appear each second, while lower frame rates can make motion appear choppier.

Pulse repetition frequency describes how many ultrasound pulses are emitted each second, and pulse repetition period is the time between those pulses; those terms relate to the timing of pulses, not directly to how many images are shown per second. Pulse duration is the actual length of each emitted pulse, which affects axial resolution but not the rate at which frames are displayed.