Chapter 4: Describing Pulse Waves

Why are ultrasound waves sent in pulses instead of continuously?

We do not continuously send sound into the body to minimize bio effects

True or false: continuous waves produce images

False; the machine needs “off” time to process and listen

Define pulse duration (PD)

The time it takes to complete one pulse (the “on” time)

What is the formula for pulse duration?

PD = T x number of cycles in one pulse

PD = number of cycles in one pulse divided by f

Pulse duration (PD) is determined by:

the sound source only

The distance that a pulse takes up in space from the start to the end of one pulse is called:

Spatial pulse length (SPL)

What is the formula for SPL?

length of each cycle (wavelength) times the # of cycles in a pulse

SPL is determined by the:

Sound source and the medium

What are the three parameters that can be adjusted by adjusting depth in a pulsed wave?

PRP, PRF and DF

The number of pulses per second that the ultrasound system sends/transmits

Pulse repetition frequency

The time from the start of one pulse to the start of the next pulse

Pulse repetition period