Physics

Question 1

Specular reflectors are strong/weak? Scatterers are strong/weak reflectors?

Answer 1

Specular= strong Scatteres= weak

Question 2

Does high frequency go with increased scatter?

Answer 2

Yes

Question 3

another term for axial

Answer 3

longitudinal

Question 4

what are the main variables affecting the following resolutions: 1) Longitudinal/axial- ? 2) Lateral-?

Answer 4

Longitudinal/axial = frequency (wavelength) Lateral= Beam width & Focus

Question 5

what maneuver is helpful to eliminate near field (“Bang”) artifact?

Answer 5

contrast

Question 6

if you see arcuate things on the echo, what artifact is it? (Physics II)

Answer 6

side-lobe

Question 7

which variable determines the max depth imaged?

Answer 7

PRP (Pulse Repetition Period)

Question 8

• floats over the cardiac structures, won’t move with cardiac structures, due to PRP NAME THE ARTIFACT

Answer 8

Range Ambiguity Artifact

Question 9

if the go-return time is 13 microseconds, what was the reflector depth? total distance travelled?

Answer 9

1cm deep in the body 2cm

Question 10

in the artifact with the pleural effusion looking like it is floating in the middle of the LV, what was its name?

Answer 10

range ambiguity artifact. (change the depth to bring the effusion into the window and the LV then looks normal.)

Question 11

name the artifact caused by mech valve that looks like a comet tail

Answer 11

reverberation artifact

Question 12

are artifacts from low pressure gas bubbles better see with fundamental or harmonic imaging?

Answer 12

harmonic

Question 13

v = f x ?

Answer 13

wavelength

Question 14

wavelength of 3 MHz sound wave = ? in soft tissue

Answer 14

0.5 mm

Question 15

a 3 dB change does what to intensity? how about 30dB?

Answer 15

doubles 1000 fold change (10^3): 30–> 10^3

Question 16

what happens with high MI (>1) and low MI (

Answer 16

> 1 –> bubbles destroyed weak harmonic signals

Question 17

eq’n for Acoustic Impedance (Z) what happens if Z very different b/w mediums (e.g. bone and soft tissue)?

Answer 17

Z = density x V - sound gets reflected (proportional to difference of Z’s SQUARED), not transmitted (V = velocity of sound)

Question 18

What is relationship b/w acoustic impedance (Z) and % beam that is reflected?

Answer 18

difference of Z’s SQUARED

Question 19

relationship b/w frequency and scattering

Answer 19

directly proportional

Question 20

is diffraction greater with larger or smaller transducer?

Answer 20

smaller

Question 21

the summation of losses due to reflection, scattering and absorption = ?

Answer 21

attenuation

Question 22

what is the amount of attenuation in dB/cm/MHz in soft tissue?

Answer 22

1 dB/cm/MHz

Question 23

most common Piezoelectric crystal used

Answer 23

PZT (lead zirconate titrate)

Question 24

purpose of backing block in transducer

Answer 24

absorbs sound wave and limits ringing of crystal to allow for more discrete U/S pulse

Question 25

purpose of matching layer in transducer

Answer 25

matches crystal to skin acoustic impedance to improve U/S transmission into tissues

Question 26

name the type of transducer that has CRYSTAL IMPURITIES, a BACKING BLOCK, and HARMONIC IMAGING

Answer 26

Wide Bandwidth transducer (Low Q-factor)

Question 27

for CW, would you use wide or narrow bandwidth transducer?

Answer 27

narrow

Question 28

time b/w transducer pulses = ?

Answer 28

PRP

Question 29

PRP's relation to depth?

Answer 29

directly proportional

Question 30

PRF = ?

Answer 30

1/PRP

Question 31

definition of duty factor and values for CW and PW

Answer 31

- fraction of PRP that emits sound CW = 1 , PW .001

Question 32

resolution along the length of the beam =?

Answer 32

axial resolution

Question 33

a 3MHz trasnducer has how much wavelength?

Answer 33

.5mm

Question 34

which resolution is determined by spatial pulse length?

Answer 34

axial

Question 35

(cycles x wavelength)/2 = ?

Answer 35

resolution

Question 36

how can you better separate fundamental and harmonic signal?

Answer 36

use longer pulse

Question 37

does a wider or narower beam improve lateral resolution?

Answer 37

narrow

Question 38

does higher frequency mean higher lateral resolution?

Answer 38

yes

Question 39

does higher frequency improve lateral AND axial resolution?

Answer 39

yes

Question 40

does amplification ("increasing gain") effect the signal to npise ratio or contrast bubbles

Answer 40

no

Question 41

modified doppler eq'n

Answer 41

Question 42

nyquist limit (delta f) = ?

Answer 42

PRF/2

Question 43

the highest doppler shift that can be measured w/ pulsed doppler is called?

Answer 43

nyquist limit

Question 44

at what relative depths and frequencies can you measure higher velocities?

Answer 44

shallower depth, lower frequencies

Question 45

is COlor Flow Imaging CW or PW?

Answer 45

PW

Question 46

what will more pulses with color flow imaging do to frame rate?

Answer 46

make it slower

Question 47

Z/PRP = ? | (Z = distance)

Answer 47

velocity

Question 48

Eq'n for Duty Factor

Answer 48

Pulse Duration/PRP = DF

Question 49

for every 3dB attenuation, how much reduciton in intensity is there? what about for 10dB attenuation?

Answer 49

3dB--\> 1/2 10dB--\> 1/10

Question 50

Answer 50

D

Question 51

the frequency range for audible sound? U/S?

Answer 51

20Hz-20kHz | (U/S \> 20kHz)

Question 52

Answer 52

B: Frame rate

Question 53

4 ways to improve temporal resolution

Answer 53

DECREASE: depth, width, #focal points, line density

Question 54

Answer 54

D- speed of sound always 1540 m/s

Question 55

will increasing gain increase output power? what will inc output power?

Answer 55

no. M.I.

Question 56

In soft tissue, every 13 microsecond of go-return time means the reflector is \_cm deep in body?

Answer 56

1

Question 57

recite the 13 microsecond table

Answer 57

Question 58

lateral resolution is dependent on the ___ of the ultrasound beam?

Answer 58

width

Question 59

PRF =?

Answer 59

PRF = 77,000/depth

Question 60

modified doppler velocity equation from physics lecture

Answer 60