A short burst of acoustic energy to create every picture of anatomy

Typically consists of 2-4 cycles each in ultrasound

Series of individual cycles that move through a medium as a single unit

ALSO a collection of cycles that travel together

1 pulse = transmitting and listening time

Pulse duration

Spatial pulse length

Pulse repetition period

Pulse repetition frequency

Duty factor

All are determined by the ultrasound machine

Actual time of the pulse from start to end

The "talking" phase of a single transmission

Typical value: 0.3-2.0 μs per cycle

Determined by the source

Cannot be adjusted 

Shorter PD create better images

PD = (# cycles in pulse)*(period μs)

• Directly proportional to the number of cycles in the pulse AND to the period

PD = (# cycles in pulse) ÷ (frequency MHz)

• Inversely proportional to the frequency

The distance a pulse occupies in space from start to end

Typical values: 0.1-1.0 mm in soft tissue

Determined by the source and the medium due to relationship with wavelength

Cannot be altered by sonographer

SPL = (#cycles)*wavelength

Directly proportional to the number of cycles in each pulse AND to the wavelength of each cycle

Inversely proportional to the frequency of the cycle 

Time from the start of one pulse to the start of the next pulse

Includes pulse duration (talking time) and listening time

Typical values: 100μs - 1ms (approximately 1000x longer than pulse duration)

Not related to period

Determined by sound source

Adjustable by sonographer by changing listening time, which changes when depth is changed

Imaging Depth 

aka Depth of View

Describes the max distance into the body that our ultrasound system is imaging at any time

Controlled by sonographer via depth knob

Indicated by tiny white arrow

Directly related to pulse repetition period

Number of pulses that occur in one second

Typical values 1-10 kHz (pulses/second)

Determined by sound source

Unrelated to frequency

Alterable by the sonographer by changing depth of view; inversely related to DOV due to length of listening time

Percent or fraction of time the system is transmitting

Pulse is on

DF = PD ÷ PRP

Typical values: 0.002-0.005 (0.2-0.5%)

Determined by sound source

Adjustable by sonographer as is inversely related to depth of view

A value of 1 indicates continuous wave systems in which there are two transducers - one to transmit, one to listen