Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

PVI > Ultrasound physics > Flashcards

Ultrasound physics Flashcards

1
Q

which transducer to use

A

highest frequency

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

temporal resolution

A

frame rate

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

improved axial resolution

A

higher frequencies

along the axis of US beam

90 degrees to skin

Y-axis

depth resolution

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

improved lateral resolution

A

adjust focal zone

x axis - right left aspect of image

better with higher frequencies

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

improve temporal resolution

A

minimize depth

adjust frame rate

use narrow sector

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

benefits of compound imaging

A

reduces speckle

increases frame rate due to longer scan time

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

effect of harmonic imaging

A

decreases frame rate

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

acoustic power units

A

watts

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

watts =

A

joules/sec

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

intensity (thermal index/mechanical index)

A

power/beam area MW/cm2

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

mechanical index

A

likelihood of a non thermal bioeffect such as cavitation (compression and decompression of tissue)

17 mW/cm2 ophthalmic related to intensity of pulse max

value of peak negative pressure/sq root of acoustic center frequency

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

thermal index

A

ratio of the emitted acoustic power to the power to raise the temperature by 1 degree

acoustic power at depth of interest/ estimated power to elevate temp 1 degree

larger TI means larger heating potential

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

application specific exposure limits in mW/cm2 peripheral vascular cardiac fetal ophthalmic

A

720 mW/cm2 peripheral vascular

430 mW/cm2 cardiac

94 mW/cm2 fetal

17 mW/cm2 ophthalmic

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

according to J of US

0.23 W/cm2 (versus 1.9 for other organs)

ISPPA = spatial-peak pulse-average intensity

A

mechanical index

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

specular reflection

A

at smooth surfaces such as bone, diaphragm, tendons calcifications, valves, needles

angle dependent

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

mirror image artifact

A

90 degrees duplication at site of a strong reflector

far image is false image

1 reflector send it back to the other delay in sending back leads to duplicate

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

back scattering

A

associated with most tissues

less angle dependent

rough surface

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

Rayleigh scatter

A

blood - RBC’s smaller than wavelength

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

shadowing

A

decreased echoes behind strong reflector

20
Q

refraction

A

reflector placed improperly

displaced laterally

greater change in impedance, greater bending

21
Q

range ambiguity

A

echo received at different interval

22
Q

reverberation

A

bouncing between 2 strong reflectors looks like multiple equally spaced lines

ex: comet tail artifact, ring down artifact

23
Q

pencil probe Doppler

A

CW - no angle correction

24
Q

duplex

A

B mode and Doppler

25
Q

Doppler equation: change in frequency

A

(2 x transmitted frequency x velocity x cosine theta)/ speed of sound = 1540 m/s

26
Q

Doppler equation: velocity

A

change in frequency x 1540 m/sec/ 2 x

frequency x cosine theta

cosine theta is smaller greater than 60 degrees making the velocity greater when dividing otherwise 1 at angle 0

27
Q

cosine 0

A

1

28
Q

cosine 30

A

.86

29
Q

cosine 60

A

0.50

30
Q

cosine 90

A

0

31
Q

benefit pulsed wave

A

measure from depth

32
Q

disadvantage pulsed wave

A

aliasing

can’t record super high velocities

33
Q

number of crystals with Doppler

A

pulsed - 1

CW - 2 (can detect higher velocities)

34
Q

advantage CW

A

picks up everything

better signal to noise

not range gated

higher velocities (2 crystals)

35
Q

PRF (pulse repetition frequency)

A

SCALE

36
Q

PRF to elicit aliasing

tips to decrease aliasing

A

1/2 PRF = Nyquist frequency

to avoid aliasing, PRF must be 2X frequency of signal detected

*****************************

adjust baseline and scale

try lower frequency

37
Q

type of Doppler for color Doppler

A

pulsed wave

38
Q

decreased angle

A

decreased velocity

39
Q

to ascertain angle correctly

look at which vessel wall

A

back wall

40
Q

p 21 of physics

A

drop image of MI and TI

41
Q

tips to decrease aliasing

A

adjust scale and baseline

try lower frequency

42
Q

contributors for aliasing

A

deeper vessels

higher velocities

43
Q

volume flow rate

A

pressure difference x radius 4/

8 (PI) viscosity x length

44
Q

volume flow rate

A

P1-P2/R

= pi (pressure difference) x radius 4/

8 x (viscosity) x (length)

45
Q

Pouseille’s law

volume flow =

pressure/resistance

A

as radius decreases,

resistance increases

(P1-P2) π r4/

8 N L

N- viscosity

L - length

PVI (9 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions