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47 Cards in this Set
- Front
- Back
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what are the parameters of a continuous sound wave |
-period -frequency -amplitude -power -intensity -wavelength -propagation speed |
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what are the parameters of a pulse echo wave |
-pulse duration -spatial pulse length -pulse repetition period -pulse repetition frequency -duty factor AND -period-frequency-amplitude-power-intensity-wavelength-propagation speed |
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what can a continuous wave not do? |
produce an image |
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what does pulse sound do |
-produce short burst, or pulses of acoustic energy to create pictures -a pulse of ultrasound is a collection of cycles that travel together |
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what must a pulse sound have? |
a beginning and an end -pulse is made up of individual cycles but the entire pulse moves as a single unit. |
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Wave |
means of transferring energy |
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how many crystals does a continuous wave have? and how does it work |
two, one is always transmitting and the other is always receiving |
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what are the two components of pulsed ultrasound? |
1) transmit, talking, or "on" time 2) receive, listening, or "off" time |
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Shallow Imaging |
-image is in real time -decreased Pulse Repetition Period (PRP) -increased Pulse Repetition Frequency (PRF) -increased Duty Factor |
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Deep Imaging |
-images are delayed -increasedPulse Repetition Period (PRP) -decreasedPulse Repetition Frequency (PRF) -decreased Duty Factor |
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Pulse Duration |
-the actual time from the start of a pulse to the end of that pulse -microseconds(time) -determined by the sound source -not adjustable by the sonographer -PD is equal to # of cycles in each pulse ** PD= #of cycles*period |
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Why is it better to have a shorter pulse duration? |
shorter=better(greater accuracy in realtime) |
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Spatial Pulse Length |
-the distance in one pulse transmission -mm(distance) -determined by both the source and medium -not adjustable by the sonographer ** SPL= #of cycles*wavelength |
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Pulse Repetition Period |
-the amount of time from the start of one pulse to the start of the next -ms(time) -determined by the source (depth only) -can be adjusted by sonographer (by adjusting the depth)(just listening, not transmitting) -reciprocal of PRF ** PRP=1/PRF |
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Pulse Repetition Frequency |
-the number of pulses in one second -Hz -determined by the source (depth only) -can be adjusted by sonographer (by adjusting the depth)(just listening, not transmitting) -reciprocal of PRP ** PRF=1/PRD |
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Duty Factor |
-the percentage or fraction of time that the system transmits a pulse -no units % -determined by sound source (depth and PD) -can be adjusted by sonographer with depth and manipulated by frequency if you change XDR ** DF=PD/PRP*100% |
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what does depth of view describe? |
the maximum distance into the body that an ultrasound system is imaging *sonographer controls depth of view |
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the sonographer can't change the _____ but can alter the ______ when adjusting the image depth. |
pulse duration listening time |
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Pulse duration is _____ proportional to the number of cycles in the pulse |
Directly proportional |
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Pulse duration is _____ proportional to period |
Directly proportional |
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Pulse duration is _____ proportional to frequency |
Inversely proportional |
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Spatial Pulse Length is _____ proportional to wavelength. |
Directly proportional |
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Spatial Pulse Length is _____ proportional to frequency |
Inversely proportional |
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Spatial Pulse Length is _____ proportional to the number of cycles in the pulse |
Directly proportional |
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what happens to the # of cycles in pulse waves and the wavelength when it becomes a long pulse? |
many cycles and longer wavelengths |
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what happens to the # of cycles in pulse waves and the wavelength when it becomes a short pulse? |
fewer cycles and shorter wavelengths |
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What is more desirable? shorter or longer waves and why? |
Shorter length are more desirable for more accurate images |
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at shallow depths, the time from one pulse to the next is _____. |
short |
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at more depth, the time from one pulse to the next is _____. |
longer |
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how is PRP related to period? |
unrelated |
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what causes short listening time |
Short PRP |
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what causes long listening time |
Long PRP |
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how are pulse repetition period and depth of view related |
Directly related |
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as depth of view increases, pulse repetition period _____. |
increases |
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as depth of view decreases, pulse repetition period _____. |
decreases |
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transmit time is also called what? |
Pulse Duration |
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in deeper imaging the listening time and pulse repetition period _____. |
lengthen |
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in shallower imaging the listening time and pulse repetition period _____. |
shorten |
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if the imaging is shallow the pulse repetition frequency is _____. |
higher |
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if the imaging is deep the pulse repetition frequency is _____. |
lower |
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how is pulse repetition frequency related to frequency? |
unrelated (only related to depth of view) |
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pulse repetition frequency and depth of view are related how? |
inversely related |
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how are pulse repetition frequency and pulse repetition period related to each other? |
Inversely related and reciprocals |
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longer pulse repetition period results in a _____ pulse repetition Frequency. |
lower |
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shorter pulse repetition period results in a _____ pulse repetition Frequency. |
higher |
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duty factor is ______ related to imaging depth |
inversely related |
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duty factor is higher when imaging at _____ depths and lower when imaging at _____ depths. |
shallow depths greater depths |
