Point of Care Midterm
Terms in this set (59)
What are the biological effects of ultrasound?
Thermal (cavitation - contrast only) with 4˚C increase, especially important for fetuses and eyes (not proven)
spatial peak temporal average
What is the relationship between wavelength and frequency
What frequencies do we generally use for ultrasound imaging?
What is the relationship between intensity and output power?
What is intensity?
concentration of power per unit area
What is attenuation?
the loss of energy as it travels through tissues
If we use a high frequency transducer, how quickly will the energy be attenuated?
If we use a low frequency transducer, how quickly will the energy be attenuated?
What is the default ultrasound mode?
What appears black and represents fluid filled structures?
What appears gray, reflects less than surrounding structures, and represents soft tissue?
What appears gray, reflects equal to surrounding structures, and represents soft tissue?
What mode is the "motion-mode" that analyzes the movement of structures over time?
What mode is used to measure the size of the cardiac chambers, movement of cardiac valves, measure change in inferior vena cava, or used to evaluate lung pleura?
What mode is not used very often anymore and displays dots on the screen?
What mode uses color to show a shift of frequency of sound waves due to motion?
color flow doppler
What mode measures velocity and helps us determine if flow is occurring in the right direction?
What are the four types of transducers?
linear, curvilinear, phased-array, intracavitary
What are the two types of low frequency transducers?
curvilinear and phased-array
What are the two types of high frequency transducers?
intracavitary and linear
What transducer has a high frequency (good resolution, shallow penetration) and is used to look at superficial structures (eyes, blood vessels, nerves, muscles, joints, & ultrasound guided procedures)
What transducer has a low frequency (less resolution, deep penetration) and is used to look at structures in the abdomen (liver, spleen, kidneys, bladder) as well as large musculoskeletal structures (shoulders, hips)
What transducer has a low frequency, is used to look at moving structures (like the heart and lungs) and is often used to look between ribs?
What transducer has a high frequency, is used transvaginally and transrectally, and is used to look at the pharynx?
phased array transducer
What is ALARA and why is it important in ultrasound
AS LOW AS REASONABLY ACHIEVABLE - don't stay on one spot or use too many modes, as this can create heat - critical in fetal sonography
What are artifacts?
false images, or parts that do not represent true anatomic structures
What causes acoustic shadowing?
solid structures that absorbs sound waves (indicates stones, bones, or air)
Where are superficial structures viewed on an image?
top of screen
Where are deep structures viewed on image?
bottom of screen
Where should the structure of interest be seen on an image?
To see sagittally, where should everything be located?
Patient on back
To see coronally, where should everything be located?
Patient on side
To see transverse, where should everything be located?
Patient on back
What is the element in the transducer?
If the element in the transducer is thin, what does that say about its frequency?
If the element in the transducer is thick, what does that say about its frequency?
What is the A-mode used for?
to look at baby's temple
What type of doppler measures highest velocity?
Acoustic enhancement indicates what?
reverberation occurs because
of the difference in returning echos, sound gets trapped, happens in pleural space
mirroring looks like what?
two identical organs
sound with a bend
refraction occurs when imaging
soft tissue/fat organs (abdomen)
What are artifacts of wave propagation?
reverberation & mirroring
What is an artifact due to velocity errors?
What is an artifact due to beam characteristics?
What is an artifact due to wave attenuation?
acoustic shadowing and enhancement
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