Test 2

Question 1

what are annular arrays?

Answer 1

concentric rings of piezoelectric material

Question 2

what does annular arrays do for us?

Answer 2

no electric focus, all natural focusing

Question 3

what produces multiple foci?

Answer 3

smallerst layer to larger layer

Question 4

how we do make mulptiple foci now with our machine?

Answer 4

electronic focusing and image pre-processing

Question 5

what are some invasive transducers?

Answer 5

• transvaginal
• transrectal
• transesophageal
• cathedar mounted

Question 6

what does invasive trasnducers allow for?

Answer 6

closer to the tissues-higher res

less attenuation

Question 7

attenuation equation

Answer 7

A= 1/2f x l

Question 8

what factors are we affecting with invasive transducers?

Answer 8

decreasing length by getting closer to tissues

Question 9

what is resolution?

Answer 9

visably seperating 2 structures

Question 10

what resoltuion is apart of the transducer?

Answer 10

detail

Question 11

what are aspects of resoltuion?

Answer 11

detail
contrast
temporal

Question 12

what are the 3 aspects of detail resolution?

Answer 12

• lateral
• axial
• elevational

Question 13

axial resoltion?

Answer 13

minimum reflector seperating objects ALONG the scan line

Question 14

Axial res equation

Answer 14

Axial res (mm) = SPL/2

Question 15

how do we improve axial resolution?

Answer 15

SPL-smaller the better

Question 16

how do we reduce wavelength?

Answer 16

altering freq

Question 17

how do we reduce number of cycles?

Answer 17

reduced by damping

Question 18

laterla resolution?

Answer 18

seperating objects that are PERPINDICULAR to the scan line

Question 19

lateral resolution equation?

Answer 19

lateral res (mm)= Wb

Question 20

elevational resolution

Answer 20

section thickness/partial volume artifact

Question 21

what are characteristics of blood flow?

Answer 21

• volumetric flow rate (poiseulle equation)
• types of flow
• continuity rule
• bernoulli effect

Question 22

what is volumetric flow rate?

Answer 22

volume of blood passing a point per second/minute

LONG STRAIGHT TUBE

Question 23

when does blood only flow?

Answer 23

only if there is a pressure gradient

Question 24

what is volumetric flow rate equation?

Answer 24

Q=P/R

Question 25

what is Poiseuille's equation?

Answer 25

Q porp. Pd4/ln

Question 26

what are the types of flow?

Answer 26

``` Laminar -plug -parabolic -disturbed Non Laminar -tubulent ```

Question 27

what is the average flow speed in parabolic hemodynamics?

Answer 27

1/2 fastest speed

Question 28

is distubed flow still laminar?

Answer 28

yes (non parobolic)

Question 29

what flow is non laminar?

Answer 29

turbulent

Question 30

how is pulsatile arterial flow characterized?

Answer 30

- compliance of the vessel walls | - expansion and contraction of non-rigid vessel walls

Question 31

what does compliance allow for?

Answer 31

- added forward flow | - reversal of flow

Question 32

what is the windkissel effect?

Answer 32

1. pulse forces fluid into the vessel and vessel distends 2. aortic valve closes, decreasing driving pressure 3. vessel contracts, pushes blood forward

Question 33

reversal of flow?

Answer 33

- due to contraction of extended vessels during diastole | - no valves to prevent backward flow

Question 34

what is the continuity rule?

Answer 34

keep vol. flow rate contant speed will increase

Question 35

what is the continuity rule equation?

Answer 35

Q=V x A

Question 36

what tube is the continuity rule for?

Answer 36

SHORT SEGMENTS

Question 37

for contunituty rule of area decreaes what happens to velocity?

Answer 37

increased (keep Q constant)

Question 38

what is the bernoulli effect?

Answer 38

decrease in pressure in regions of high flow speed

Question 39

what is velocity inversly proportional to?

Answer 39

pressure

Question 40

what is the doppler effect?

Answer 40

change in frequency caused by the motion of a source, reflector or reciever

Question 41

when is the doppler shift positive?

Answer 41

gettting closer and the freq goes up

Question 42

what is the doppler equation (t and r)

Answer 42

Fd = Fr -Ft

Question 43

what is the doppler equation?

Answer 43

Fd = 2 x fo x v/c

Question 44

what is the doppler equation with veolocity?

Answer 44

v= 77 x fd/ fo

Question 45

what are the steps of doppler?

Answer 45

1. transducer sends a pulse to a moving object 2. transducer recieves new f and calculates doppler shift 3. doppler shift depends on the objects velocity 4. machine calculates speed based on doppler shift

Question 46

how much doplper shift will occur if the angle of interrogation is non zero?

Answer 46

lesser doppler shift will occur

Question 47

cos0

Answer 47

1

Question 48

cos30

Answer 48

0.87

Question 49

cos60

Answer 49

0.5

Question 50

cos1

Answer 50

0

Question 51

what happens when the doppler shift is smaller than it should be?

Answer 51

the calculated velocity appears smaller

Question 52

what must a sonographer do to acheive an angle close to 0?

Answer 52

heel toe | phase (steer)

Question 53

what information are we getting for colour doppler?

Answer 53

- presence - direction - speed - character

Question 54

how many echoes are recieved with colour doppler?

Answer 54

10

Question 55

beam former sends digitzed voltages to the __________

Answer 55

signal processor

Question 56

signal processor deteects doppler shifted echoes useing___________

Answer 56

autocorrelation

Question 57

autocorrelation

Answer 57

mathematical technique that determines mean and variance of doppler shift signal

Question 58

how many pulses are sent out per scan line in colour doppler?

Answer 58

3-32

Question 59

what does more pulses sent out per scan line do?

Answer 59

increase accuracy and sensitivity but it reduces frame rate

Question 60

what does the signal processor calculate and display?

Answer 60

- mean - varience - power

Question 61

what is power?

Answer 61

intensity of echo related to amplitude

Question 62

what does power depend on?

Answer 62

reflectors-more reflection more echoes impedence-higher Z, more echo concentration of RBC's-more reflectors, more echo

Question 63

what is the only thing power uses?

Answer 63

uses only the power/strength of doppler shifts

Question 64

what are pros of power doppler?

Answer 64

- no aliasing - angle independant - increased sensitivity

Question 65

what are the cons of colour doppler?

Answer 65

- no direction - no flow speed info - no flow character - cannot catch a stenosis

Question 66

hue

Answer 66

colour itself

Question 67

saturation

Answer 67

richness of color

Question 68

luminence

Answer 68

brightness

Question 69

how does box size affect FR?

Answer 69

bigger the box, less lines per frame??

Question 70

what happens when we lower PRF?

Answer 70

- allows to pick up slower flow | - increases chance of aliasing

Question 71

where in the instrument does the gain happen?

Answer 71

amplifiers in the beam former

Question 72

what is esemble length?

Answer 72

number of pulses used for each colour scan line

Question 73

echoes _______ cut off amplitude will show as colour

Answer 73

below

Question 74

stronger echoes show as ________-

Answer 74

greyscale

Question 75

what happens when priorty is set too low?

Answer 75

noise or artifacts within the vessel are displayed with little colour

Question 76

what happens when priority is set too high?

Answer 76

fills the vessel with colour esp. when there is a low signal to noise ratio

Question 77

does duplex scanning happen all at once?

Answer 77

no, tranducer does one at a time | -simultaneous does not exist