# Shared Flashcard Set

## Details

US Physics (Edelman)
Chapter 4
38
Physics
Professional
06/17/2011

Term
 Pulse Duration
Definition
 The actual time from the start of a pulse to the end of that pulse.
Term
 Units for pulse duration
Definition
 time such as micro seconds, milliseconds or seconds
Term
 Pulse duration is determined by
Definition
 sound source only
Term
 Pulse duration is controlled by
Definition
 the ultrasound system and transducer
Term
 Pulse duration formula
Definition
 # cycles in pulse pulse duration (usec) =  ______________                                   frequency (MHz)
Term
 Spatial pulse length
Definition
 The distance that a pulse occupies in space from the start to the end of a pulse.
Term
 units for spatial pulse length
Definition
 distance  ex   mm
Term
 Typical values for spatial pulse length in soft tissue
Definition
 0.1 to 1.0 mm
Term
 Spatial pulse length is determined by
Definition
 the source and the medium
Term
 Spatial pulse length is directly proportional to
Definition
 the number of cycles in the pulse   and also   the wavelength
Term
 Spatial pulse length is inversely proportional to
Definition
 frequency
Term
 Pulse duration is
Definition
 the time the pulse is on typically measured in microseconds
Term
 Pulse length is
Definition
 the distance of the pulse start to end typically measured in mm
Term
 Pulse repetition period
Definition
 the time from the start of one pulse to the start of the next pulse.
Term
 units for pulse repetition period
Definition
 time such as ms
Term
 Typical values for pulse repetition period
Definition
 100 microseconds to 1 millisecond
Term
 Pulse repetition period is determined by
Definition
 the sound source only
Term
 If all other factors remain the same, what happens to duty factor if the sonographer changes to a transducer with a longer pulse duration?
Definition
 It increases
Term
 Pulse repetition period is changed by the sonographer in what way?
Definition
 The operator changes on the listening time when adjusting the depth of view but never the pulse duration.
Term
 Pulse repetition period is determined
Definition
 by the depth of view   as imaging depth increases, PR period increases as imaging depth decreases, PR period decreases
Term
 Pulse repetition frequency (PRF)
Definition
 is the number of pulses that an ultrasound system transmits into the body each second.
Term
 units for PRF
Definition
 hertz  Hz   or   per second
Term
 Typical values for PRF
Definition
 1000 to 10000 hertz   or     1 to 10 thousand pulses per second
Term
 PRF is determined by
Definition
 the sound source
Term
 PRF is adjusted by the sonographer how?
Definition
 by adjusting the depth of view
Term
 when imaging shallow the PRF is
Definition
 high
Term
 when imaging deep the PRF is
Definition
 low
Term
 Is PRF related to frequency?
Definition
 no   it is related only to depth of view
Term
 How are PRF and depth of view related?
Definition
 inversely
Term
 PRP and PRF are related how?
Definition
 inversely   they are reciprocals
Term
 Duty Factor
Definition
 the percentage or fraction of time that the system is transmitting a pulse
Term
 units for Duty Factor
Definition
 none   it is a percentage
Term
 typical values for duty factor
Definition
 0.002 to 0.005 or 0.2% to 0.5%
Term
 duty factor is determined by
Definition
 the sound source only
Term
 Duty Factor is changed by the sonographer in what way?
Definition
 by changing the imaging depth
Term
 formula for duty factor
Definition
 pulse duration   duty factor (%)  =  ___________________ x 100                  pulse repetition period
Term
 When the sonographer changes the imaging depth what parameters are changed?   Hint there are Three of them
Definition
 PRP, PRF, Duty Factor
Term
 The two components of the PRP are?
Definition