Flash Cards Chapter 4

8/7/2019 Flash Cards Chapter 4

1/66

Physics Flash cards

Chapter 4

What are the five

parameters thatcompletely describe

pulsed sound?


2/66

Physics Flash cards

Chapter 4

Pulse duration (PD)

Pulse repetition period (PRF)

Pulse repetition frequency(PRF)

Duty factor

Spatial pulse length (SPL)


3/66

Physics Flash cards

Chapter 4

What are the two

components ofpulsed ultrasound?


4/66

Physics Flash cards

Chapter 4

Transmit- talking or on

time Receive, listening or

off time


5/66

Physics Flash cards

Chapter 4


6/66

Physics Flash cards

Chapter 4

Define Pulse duration

(PD)


7/66

Physics Flash cards

Chapter 4

the actual time from the

start of a pulse to the end ofthat pulse


8/66

Physics Flash cards

Chapter 4

What are the units of PD?

What is a typical value for PD?

What PD is determined by?


9/66

Physics Flash cards

Chapter 4

Can PD be adjusted?

PD is in units of timeTypical values of 0.3 to 2.0s

PD is determined by the sound source


10/66

Physics Flash cards

Chapter 4

PD cannot be adjusted, natural of the

transducer

What is the equation(s) for

PD?


11/66

Physics Flash cards

Chapter 4

PD (s) = # of cycles per pulseXperiod (s)

Or


12/66

Physics Flash cards

Chapter 4

PD (s) = # of cycles per pulse Frequency(MHz)

Explain PD relationship to

# of cycles in the pulse

period


13/66

Physics Flash cards

Chapter 4

frequency

PD# of cycles per pulse

PDperiod


14/66

Physics Flash cards

Chapter 4

PD1frequency

What characteristicsdistinguish pulses

with long duration


15/66

Physics Flash cards

Chapter 4

from those with short

duration?Long duration- many

cycles, long periods


16/66

Physics Flash cards

Chapter 4

Short duration- few

cycles, short periodsWhich type of pulse ismore desirable in


17/66

Physics Flash cards

Chapter 4

diagnostic imaging and

why?


18/66

Physics Flash cards

Chapter 4

Shorter duration pulses

are desirable indiagnostic imagingbecause they create


19/66

Physics Flash cards

Chapter 4

images of greater

accuracy.What is spatial pulselength (SPL)?


20/66

Physics Flash cards

Chapter 4

Spatial pulse length is the

distance that a pulse


21/66

Physics Flash cards

Chapter 4

occupies in space from

the start to the end of apulse.

What are the units ofSPL?


22/66

Physics Flash cards

Chapter 4

What is the typical value

of SPL?What determines SPL?

Is SPL adjustable? SPL is in units of distance.


23/66

Physics Flash cards

Chapter 4

Typical length for soft tissue,0.1 to 1.0 mm

SPL is determined by both thesource and the medium.

SPL is not adjustable,transducer fixed.


24/66

Physics Flash cards

Chapter 4

What is the SPL

equation?


25/66

Physics Flash cards

Chapter 4

SPL= # of cycles per pulse x

wavelength


26/66

Physics Flash cards

Chapter 4

What is SPL relationship with

# of cycles within a pulse

Wavelength

Frequency?


27/66

Physics Flash cards

Chapter 4

SPL

# of cycles within apulseSPLwavelengthSPL 1frequency


28/66

Physics Flash cards

Chapter 4

What is the differencebetween PD and SPL?


29/66


30/66

Physics Flash cards

Chapter 4

Which characteristicsdistinguish pulses with long

pulse length from those withshort length?


31/66

Physics Flash cards

Chapter 4

Two characteristics create longpulses, many cycles, and

longer wavelengths. And, twocreate short pulse lengths;fewer cycles, and shorter

wavelengths.


32/66

Physics Flash cards

Chapter 4

Which type of pulse is more

desirable in diagnostic imaging,and why?


33/66

Physics Flash cards

Chapter 4

Shorter pulses are desirable

because they create moreaccurate image.


34/66

Physics Flash cards

Chapter 4

What is pulse repetition period

(PRP)?


35/66

Physics Flash cards

Chapter 4

PRP is the time from the start

of one pulse to the start of thenext pulse, one PD pulse onelistening time.

PD Listening time


36/66

Physics Flash cards

Chapter 4

What are the units of PRP?

What is the typical diagnosticvalue for PRP?

What is PRP determined by?

Is PRP adjustable?


37/66

Physics Flash cards

Chapter 4

PRP is in units of time. PRP typical diagnostic value is

100s to 1ms. PRP is determined by sound source

based on the imaging depth. YES, PRP is adjustable by changing

the depth of view.


38/66

Physics Flash cards

Chapter 4

What is depth of view?


39/66

Physics Flash cards

Chapter 4

Depth of view describes themaximum distance into the

body that an ultrasoundsystem is imaging,

controlled by source user.


40/66

Physics Flash cards

Chapter 4

How are PRP and depth ofview related?


41/66

Physics Flash cards

Chapter 4

PRP and imaging depth aredirectly related. As depth of view increases,

PRP increases.


42/66

Physics Flash cards

Chapter 4

As depth of view decreases,PRP decreases.

What are the twocomponents of PRP?

Which one can the sourceuser change/control?


43/66

Physics Flash cards

Chapter 4

The two components of PRP are

PD/transit time and receive time.PD is a characteristic of thetransducer, however the receive

time varies based on the depthof the object being imaged.


44/66

Physics Flash cards

Chapter 4

What is pulse repetition

frequency (PRF)?


45/66

Physics Flash cards

Chapter 4

PRF is the # if pulses thatan ultrasound systemtransmits into the body

each second.


46/66

Physics Flash cards

Chapter 4

What are the units of PRF?

What is the typical

diagnostic value of PRF?


47/66

Physics Flash cards

Chapter 4

What is PRF determinedby?

Is PRF adjustable? PRF is in units of Hertz (per

second).


48/66

Physics Flash cards

Chapter 4

PRF typical diagnostic value is1000 (1 kHz) to 10,000Hz (10 kHz).

PRF is determined by the source. PRF can be adjusted, by changing

the depth of view.


49/66

Physics Flash cards

Chapter 4

How are PRF and depth ofview related?


50/66

Physics Flash cards

Chapter 4

PRF and depth of view areinversely related. As depth of view increases PRF

decreases. As depth of view decreases

PRF increases.


51/66

Physics Flash cards

Chapter 4

What is the relationshipbetween PRP and PRF?


52/66

Physics Flash cards

Chapter 4

PRP and PRF are inverselyrelated and are reciprocals.PRF = 1PRP

and

PRF x PRP = 1

What is duty factor?


53/66

Physics Flash cards

Chapter 4

Duty factor is the % of

fraction of time that the


54/66

Physics Flash cards

Chapter 4

system is transmitting apulse. The % of PD within

the PRP.


55/66

Physics Flash cards

Chapter 4

What are the units of dutyfactor?

What is the typical value forduty factor?


56/66

Physics Flash cards

Chapter 4

What is duty factordetermined by?

Is duty factor adjustable? Duty factor is a % of time.


57/66

Physics Flash cards

Chapter 4

0.2%-0.5% is the typical duty factor(0.2% of the PRP is the PD or dutyfactor).

Duty factor is determined by thesource only.

Yes, duty factor is adjustable bychanging the depth of view.


58/66

Physics Flash cards

Chapter 4

What is the duty factorequation?


59/66

Physics Flash cards

Chapter 4

Duty factor (%) = PDPRP x 100


60/66

Physics Flash cards

Chapter 4

What are the maximum andminimum values for duty

factor?


61/66

Physics Flash cards

Chapter 4

1 for continuous wave, 0 fortransducer at rest


62/66

Physics Flash cards

Chapter 4

How does the sonographerchange duty factor?


63/66

Physics Flash cards

Chapter 4

Duty factor is altered whenimaging depth is altered.Duty factor decreases as a

system images deeper,


64/66

Physics Flash cards

Chapter 4

increases when a systemimages more superficially.

Somethings to rememberShallow imaging Deeper imaging

Less listening More listening

Shorter PRP Longer PRPHigher PRF Lower PRF


65/66

Physics Flash cards

Chapter 4

Higher duty factor Lower duty factor

Parameter Adjustable UnitsDeterminedby Typicalvalue

PD No s, time Source0.5-3.0

s

PRP Yes ms, time Source

0.1-1.0

ms


66/66

Physics Flash cards

Chapter 4

PRF YesHz, per

secSource 1-10 kHz

SPL NoMm,

distances

Both0.1-

1.0mmDuty

factorYes None, % Source

0.2%-

0.5%

Documents

Flash Cards Chapter 4