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125 Cards in this Set
- Front
- Back
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True/False: In Diagnostic Ultrasound, Continuous Wave Sound cannot create Anatomic Images |
True |
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What do Imaging systems produce to create every picture of anatomy? |
Pulses (short bursts) of Acoustic Energy |
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Short Bursts |
Pulses |
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A Collection of Cycles that travel together is called? |
A Pulse of Ultrasound |
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What MUST a pulse have? |
Beginning and End |
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Although a pulse is made up of individual cycles, how does an entire pulse move? |
as a Single Unit |
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What consists of individual cycles, but propagates (spreads) as a single unit? |
Pulse |
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What are the TWO components of Pulsed Ultrasound? |
Transmit/Talking ("on" time) Receive/Listening ("off" time) |
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True/False: Each particular transducer emits a pulse with a fixed duration. |
True |
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True/False: The pulse duration of a transducer can be changed. |
False |
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The actual time from the start of a pulse to the end of that pulse, is called? |
Pulse Duration |
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True/False: Pulse Duration is a single transmit, talking, or "on" time. |
True |
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What type of units is Pulse Duration reported in? |
Units of time (Sec,Min) |
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What is the typical value of Pulse Duration in Diagnostic Ultrasound? |
0.3 - 2.0 microseconds (millionths of a second) |
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True/False: Pulse duration is determined by the medium through which the sound travels |
False (Pulse duration is determined ONLY by the sound source) |
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Pulse duration, Pulse Repetition Frequency and Pulse Repetition Period are determined by? |
Sound Source (ONLY) |
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What is Equal to the number of Cycles in each Pulse x the Period of each Cycle? |
Pulse Duration pulse duration (microseconds) = #cycles x period |
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What is directly proportional to the number of cycles in a pulse and period but inversely proportional to the frequency? |
Pulse Duration pulse duration = #cycles/frequency (MHz) |
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What two characteristics create pulses of long duration? |
many cycles in the pulse or individual cycles w/ long periods |
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What two characteristics create pulses of short duration? |
few cycles in the pulse or individual cycles with short periods |
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In clinical imaging, how many cycles does a typical pulse contain? |
2 - 4 cycles |
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Which type of pulse is more desirable for diagnostic imaging because it creates images of greater accuracy? |
Shorter Duration Pulse |
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What is the distance that a pulse occupies in space from start to the end of a pulse called? |
Spatial Pulse Length |
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What is the units of Spatial Pulse Length? |
units of distance (mm, cm) |
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What is the Spatial Pulse Length in soft tissue for clinical imaging? |
0.1 - 1.0 mm |
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What is determined by the source AND the medium? |
Pulse Length (spatial) + Wavelength |
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What equals the number of cycles in each pulse x the wavelength of each cycle? |
Pulse Length |
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True/False: In a particular medium, a transducer's pulse has a fixed length that cannot change |
True |
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What is directly proportional wavelength and to the number of cycles in the pulse but inversely proportional to frequency? |
Spatial Pulse Length |
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True/False: Pulses with longer durations have longer lengths |
True |
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What is the time that a pulse is "on" and is typically measured in microseconds, called? |
Pulse Duration |
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What is the distance of the pulse end to end, typically measured in millimeters, called? |
Spatial Pulse Length |
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The time that it takes a train to roll past us at a railroad crossing is called? |
Pulse Duration |
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The length of a train, from the beginning of the locomotive to the end of the caboose is called? |
Spatial Pulse Length |
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What two characteristics create LONG pulses? |
many cycles in the pulse cycles with longer wavelengths |
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What two characteristics create SHORT pulse length? |
fewer cycles in the pulse cycles with shorter wavelengths |
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Why are pulses of shorter length more desireable for imaging? |
because they create more accurate images |
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What is the time from the start of one pulse to the start of the next pulse called? |
Pulse Repetition Period |
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What is included in Pulse Repetition Period? |
one pulse + one listening time |
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What are the units used for Pulse Repetition Period? |
Time (ms,s) |
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What is the typical value of pulse duration in diagnostic ultrasound? |
100 microseconds to 1 millisecond |
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Generally, how much longer is Pulse Repetition compared to Pulse Duration? |
100 -1,000 times longer |
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True/False: Pulse Repetition Period is determined by the medium through which the sound travels |
False (It is determined by sound source Only) |
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What is determined by the imaging depth that the Sonographer selects? |
Pulse Repetition Period |
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When the depth of view is altered by the Sonographer, what else is altered? |
Pulse Repetition Period |
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When the system is imaging at shallow depths, the time from one pulse to the next is? |
Short |
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When the system is imaging more deeply, the time from one pulse to the next is? |
Longer |
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True/False: Pulse Repetition Period is unrelated to period. It is related only to depth of view. |
True |
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The Maximum distance into the body that an ultrasound system is imaging, is called? |
Depth of View |
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True/False: The Sonographer controls the depth of view |
True |
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What do the markers along the edge of an ultrasound image indicate? |
Depth |
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True/False: Pulse Repetition Period and Imaging depth are inversely related |
False PRP and Imaging depth are directly related |
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As Depth of View increases, Pulse Repetition Period does what? |
Increases |
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As Depth of View decreases, Pulse Repetition Period does what? |
Decreases |
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What are the Two Components of the Pulse Repetition Period? |
Transmit time or On time Receive time or Off time |
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What is the 'transmit time' called? |
Pulse Duration |
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Why can't the Sonographer change Pulse Duration? |
It is a character of the transducer and has a fixed value |
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What does the transducer receive from the body during the 'listening time'? |
Reflections from Anatomic Reflectors in the Body |
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What can the Sonographer alter when adjusting the imaging depth? |
Listening Time |
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With deeper imaging, the Listening Time and the Pulse Repetition Period? |
Lengthen |
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With shallower imaging, the Listening Time and Pulse Repetition Period? |
Shorten |
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Only the Listening Time portion of the Pulse Repetition Period is changed when the Sonographer alters this? |
Imaging Depth |
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The number of pulses that an ultrasound system transmits into the body each second, is called? |
Pulse Repetition Frequency |
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What focuses on the number of pulses created each second and not on the number of cycles in each pulse? |
Pulse Repetition Frequency |
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What are the units used for Pulse Repetition Frequency? |
Hertz (Hz) ( per second) |
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What is the typical value of Pulse Repetition Frequency? |
1,000 - 10,000 Hz 1 to 10,000 pulses/second |
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True/False: Pulse Repetition Frequency is determined ONLY by the Sound Source, NOT by the medium. |
True |
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True/False: Pulse Repetition Frequency is determined by the maximum imaging depth of the system. |
True |
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How can a Sonographer change Pulse Repetition Frequency of a scan? |
by adjusting the Depth of View |
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When the system is imaging shallow, the Pulse Repetition Frequency is? |
Higher |
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When the system is imaging deep, the Pulse Repetition Frequency is? |
Lower |
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True/False: Pulse Repetition Frequency is unrelated to frequency. It is only related to Depth of View. |
True |
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As Depth of View increases, Pulse Repetition Frequency does what? |
Decreases |
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As Depth of View decreases, Pulse Repetition Frequency does what? |
Increases |
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True/False: Pulse Repetition Frequency and Depth of View are inversely related |
True |
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When an ultrasound machine is imaging at a shallow depth (2 cm), what is the Pulse Repetition Frequency? |
High (the machine does not have to wait long before it sends out another pulse because the depth is shallow) |
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When an ultrasound machine is imaging at greater depth (20 cm), what is the Pulse Repetition Frequency?
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Reduced (Low) (the machine has to wait longer before it sends out another pulse) |
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True/False: Pulse Repetition Period and Pulse Repetition Frequency are inversely related |
True |
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When a Pulse Repetition Period is longer, what happens to the Pulse Repetition Frequency? |
Lowers |
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When a Pulse Repetition Period is shorter, what happens to the Pulse Repetition Frequency? |
Higher |
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In a reciprocal relationship, when two parameters are multiplied together, what is the result? |
ONE PRF = 1/PRP PRP= 1/PRF PRF x PRP = 1 |
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True/False: PRP and PRF use complimentary metric units. |
TRUE seconds (PRP) and hertz (PRF) milliseconds (PRP) and kilohertz (PRF) |
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What is the percentage or fraction of time that the system transmits a pulse called? |
Duty factor |
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True/False: Duty factor is a percentage, and therefore dimensionless. |
True |
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What is the range in Clinical Imaging of Duty Factor? |
0.002 to 0.005 OR 0.2% to 0.5% |
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When creating images, the ultrasound systems spend more or less amount of time transmitting than receiving? |
Less time transmitting (duty factor ~ 0.2%) and More time receiving (duty factor~ 99.8%) |
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What is the Duty factor for Continuous Wave Sound, and Why? |
duty factor =1.0 (100%) because the system is always transmitting |
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What is Duty Factor determined by? |
The Sound Source ONLY |
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What is the Pulse Duration divided by the Pulse Repetition Period called? |
Duty Factor |
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True/False: Changing the Depth of View of a scan does NOT change the Duty Factor. |
FALSE Changing the Depth of View CHANGES the Duty Factor |
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True/False: Duty Factor is INVERSELY RELATED to Imaging Depth. |
TRUE |
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Is the Duty Factor Higher/Lower when the Imaging System is scanning at shallow depths? |
HIGHER |
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Is the Duty Factor Higher/Lower when the Imaging System is scanning at greater depths? |
LOWER |
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What is the fraction of time during which an ultrasound system transmits a wave, called? |
Duty Factor |
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What is the time required to transmit a pulse, called? |
Pulse Duration |
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Which type of period includes both one transmit time and one receive time? |
Pulse Repetition Period |
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What is the equation for Duty Factor? |
Duty Factor (%) = (Pulse Duration/PRP) x 100 |
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What is the Maximum value for Duty Factor? |
1 or 100% |
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How is the Maximum Duty Factor achieved? |
ONLY with Continuous Wave Sound |
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True/False: Continuous Wave Sound CANNOT create anatomic images. |
TRUE |
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Duty Factors for Imaging Systems must always be less than what? |
100% |
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What is the Minimum Value of Duty Factor? |
0% |
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When does the Minimum Duty Factor Value exist? |
When the Transducer is Silent |
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At the typical value of 0.2% Duty Factor, how many times longer is the Imaging System listening versus transmitting. |
500 times |
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What do you alter on the Imaging System to change the Duty Factor? |
Imaging Depth |
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As Imaging Depth INCREASES what happens to the Pulse Duration (transmit time) and the Listening times? |
Pulse Duration remains CONSTANT Listening time is PROLONGED |
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True/False: The Duty Factor DECREASES with Deeper Imaging. |
TRUE |
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True/False: The Duty Factor INCREASES with Shallower Imaging. |
TRUE |
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When the Sonographer alters the Depth of View, what else is being altered? |
Pulse Repetition Period (PRP) |
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What happens to the Pulse Repetition Period as Imaging Depth Increases? |
Listening component of PRP LENGTHENS |
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At Shallow Imaging what happens to the.. Listening time Pulse Repetition Period (PRP) Pulse Repetition Frequency (PRF) Duty Factor |
Less Listening
Shorter PRP Higher PRF |
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At Deep Imaging what happens to the.. Listening Time Pulse Repetition Period (PRP) Pulse Repetition Frequency (PRF) Duty Factor |
More Listening Longer PRP Lower PRF Lower Duty Factor |
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When adjusting Imaging Depth, the system changes what? |
Pulse Repetition Period Pulse Repetition Frequency Duty Factor |
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What are inherent in the design of the transducer system, because they are characteristics of the pulse itself? |
Pulse Duration Spatial Pulse |
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Is the Sonographer able to change the Pulse Duration and Spatial Pulse? |
NO |
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What are the 5 parameters that describe Pulsed Waves? |
Pulse Duration Pulse Repetition Period Pulse Repetition Frequency Spatial Pulse Length Duty Factor |
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What are the building blocks of Pulsed and Continuous Waves? |
Individual Cycles |
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True/False: The parameters that describe a single cycle, can describe both Pulsed and Continuous Wave Sound. |
TRUE |
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What are the parameters that can describe Pulsed Wave Sound, Continuous Wave Sound and a Single Cycle? |
Period Frequency Wavelength Propagation Speed |
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What is the typical value for Pulse Duration? |
0.5 to 3.0 microseconds |
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What is the typical value for Pulse Repetition Period? |
0.1 to 1.0 ms |
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What is the typical value for the Pulsed Repetition Frequency? |
1 to 10 kHz |
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What is the typical value for the Spatial Pulse length? What can it be determined by? |
0.1 to 1.0 mm Source and Medium |
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What is the typical value for the Duty Factor? |
0.2% to 0.5% |
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True/False: Continuous and Pulsed Wave Sound of the same frequency are composed of identical cycles. |
TRUE |
