Ultrasound

Question 1

anechoic

Answer 1

a structure that does not produce any internal echoes

Question 2

A-Mode Amplitude modulation

Answer 2

1D US display consisting of a horizontal baseline. this baseline represents time and or distance w upward(vertical) deflections (spikes depicting the acoustic interfaces)

Question 3

attenuation

Answer 3

the US beam undergoes a progressive weakening as it penetrates the body due to absorption, scattering and beam spread. the amount of weakening is dependent on frequency, tissue density, and the # and type of interfaces

Question 4

B-Mode brightness modulation

Answer 4

2D display of US. A-mode spikes are electronically converted into dots and displayed at the correct depth from the transducer

Question 5

complex

Answer 5

refers to a mass w both fluid-filled and solid areas within it

Question 6

enhancement (acoustic)

Answer 6

sound is not weakened(attenuated) as it passes through a fluid-filled structure and therefore the structure behind it appears to have more echoes than the same tissue beside it

Question 7

frequency

Answer 7

the # of complete cycles per second (Hertz)

Question 8

gain

Answer 8

the amount of amplification of the returning echoes

Question 9

gel couplant

Answer 9

a trans-sonic material which eliminates the air interfac b/w the transducer and skin

Question 10

hypo-echoic

Answer 10

an area that has decreased brightness of its echoes relative to an adjacent structure. reflect very little sound and appear dark

ex. blood vessels, some nerves

Question 11

hyper-echoic

Answer 11

an area that has increased brightness of its echoes relative to an adjacent structure. reflect large amounts of sound (poor absorptionn) and appear bright

ex. bone, air, some nerves

Question 12

interface

Answer 12

strong echoes that delineate the boundary of organs. caused by the difference b/w acoustic characteristics of 2 adjacent organs

Question 13

M-mode

Answer 13

the motion mode displaying moving structures along a single line in the US beam

Question 14

noise

Answer 14

artifact that is usually due to the gain control being to high

Question 15

reverberation

Answer 15

artifact from a strong echo returning from a large acoustic interface to the transducer. the echo returns to the tissues again, causing additional echoes parallel and equidistant to the 1st echo

Question 16

shadowing

Answer 16

failure of the sound wave to pass through an object(ex. a bone) does not allow any sound to pass through it and there is only shadowing seen behind it

Question 17

transducer

Answer 17

a device which houses the element for transmitting and receiving US waves. Also referred to as a probe

Question 18

velocity

Answer 18

the speed at which a sound is traveling, usually 1540m/second

Question 19

the higher the frequency, the ____ depth penetration, however the _________ is improved

Answer 19

less

resolution

Question 20

the better the resolution, the ______ the clarity of the image

Answer 20

greater

Question 21

the higher the frequency,

Answer 21

the better the resolution

Question 22

what do transducers do?

Answer 22

convert 1 form of energy to another

Question 23

pulsed transducers

Answer 23

consists of 1 transducer element which functions as both the source and receiving transducers.

Question 24

doppler effect

Answer 24

the change in frequency of a wave for an observer moving relative to the source of the wave. ex. sirens