Ultrasound Instrumentation

Question 1

What does analog refer to?

Answer 1

Variable which can contain a number of variables

Question 2

What does the CRT consist of?

Answer 2

Glass vessel that contains an electron gun that is heated and produces free electrons from the cathode filament

Question 3

How are electrons accelerated across the glass container?

Answer 3

High voltage

Question 4

How is the electron beam focused?

Answer 4

By vertical and horizontal deflection plates

Question 5

What is the electron beam focused to hit?

Answer 5

Phosphor screen

Question 6

What is emitted by the phosphor screen when the electron beam hits it?

Answer 6

Light- proportional to intensity/amp of electrons

Question 7

What was the oscilloscope initially used for?

Answer 7

A-mode

Question 8

What type of CRT allows the image to be viewed directly during and after image build up?

Answer 8

Special purpose storage CRT

Question 9

What type of scanning used special purpose storage CRT?

Answer 9

B-mode scanning

Question 10

What is the most basic way of displaying US information?

Answer 10

CRT

Question 11

What replaced the use of special purpose storing CRT?

Answer 11

TV screen

Question 12

What is the positive end within the glass envelope?

Answer 12

Phosphor end

Question 13

What contains the 10000volts with in the glass envelope that applied across the tube?

Answer 13

Vacuum

Question 14

What happens when there is an increase in the amount of electrons liberated at the filament?

Answer 14

Brighter picture

Question 15

What does the control grid do?

Answer 15

Method of controlling the amount of electrons which proceed to the phosphor end of the tube

Question 16

Why is a large size of dot not the best for creating an image?

Answer 16

A large dot size will eradicate the benefits of even the best axial resolution

Question 17

What is the purpose of the focusing lens?

Answer 17

Focuses a wide stream of electrons into a narrow tightly coiled beam

Question 18

What is the purpose of the x and y focusing plates?

Answer 18

Also you to steer the electrons toward the imaging plate

Question 19

What is the storage mesh?

Answer 19

Electrons pass through the collector mesh and hit the storage mesh knocking the electrons off leaving a positively charged latent image

Question 20

What is the collector mesh?

Answer 20

Grounding device- attracts those little old dislodged electrons and safely grounds them out

Question 21

What are the flood gun(s)?

Answer 21

Spray a gentle flood of electrons towards the phosphor

Question 22

How does the latent image leave the storage mesh?

Answer 22

Electrons from the gun are attracted to the areas of positive charge on the storage mesh, and it is at these places that these electrons get through the storage mesh and to the phosphor

Question 23

What were the 2 main disadvantages of CRTs?

Answer 23

1. Image deterioration was rapid

2. Few shades of grey - bistable

Question 24

What is a analog scan converter?

Answer 24

Stores an image in one form and displays it in another form

Question 25

How does the ASC work?

Answer 25

Stores the image as a series of electrical charges on a dielectric matrix and then reads out this information for display as dots of light on a conventional television monitor

Question 26

What was the major advantage of the analog scan concerted?

Answer 26

Grey scale

Question 27

Are their flood guns in the analog scan converter?

Answer 27

No

Question 28

What is the purpose of the field mesh/anode?

Answer 28

Cause electrons to strike the target at right angles, and also to collect the stray electrons which are deposed from the dielectric matrix

Question 29

What is another name for dielectric matrix?

Answer 29

Storage target

Question 30

What is the dielectric matrix made of?

Answer 30

Silicon wafer

Question 31

What occurs to the electrons when they reach the target?

Answer 31

Dislodge electrons from the matrix leaving a positive charge forming the latent image

Question 32

How is the latent image read in the ASC?

Answer 32

Signal plate placed behind matrix- medium energy level electrons are accelerated through the positively charged areas on the matrix in a raster scan fashion

Question 33

What occurs after passing through the positively charged areas of the matrix?

Answer 33

The electron beam carries with it information regarding the relative signal amplitudes

Question 34

What controls the level of brightness or spot brightness of the US signal in the TV monitor?

Answer 34

Video signal

Question 35

How many scan lines are there in each conventional frame on a TV?

Answer 35

525

Question 36

What is the FR of a conventional TV?

Answer 36

30

Question 37

How long is each field (odd and even) formed in?

Answer 37

1/60th of a second

Question 38

What is the FR when our eyes can detect flicker?

Answer 38

20

Question 39

In A mode what does the height of deflection measure?

Answer 39

Strength of returned echo

Question 40

When is A Mode useful?

Answer 40

1. Determine whether an echo –free structure is fluid-filled or contains solid homogenous material 2. If a structure is pulsatile 3. Aid in cyst puncture 4. Use in echoencephalography

Question 41

How are echo signals represented in B-mode?

Answer 41

Brightened dots corresponding to echo intensity/amp

Question 42

What is B-mode used to display?

Answer 42

Static and real time scanners | M-mode

Question 43

What is the advantage of static B scanning?

Answer 43

Large FOV

Question 44

What are the disadvantages of static b scanning?

Answer 44

Long imaging distance Scan arm was difficult to maneuver Very operator dependent Image was static

Question 45

What is m-mode?

Answer 45

A series of B mode dots being displayed on a moving time basis

Question 46

What is a limiting factor of m-mode?

Answer 46

Represents only one anatomical plane

Question 47

What is c-mode (constant depth scanning)?

Answer 47

Incorporation of static b scanning using additional electronics

Question 48

What is PRF?

Answer 48

Number of voltage pulses sent to the transducer each second

Question 49

What are the PRF ranges?

Answer 49

4-15kHz (5-30 in Doppler)

Question 50

How should you PRF be sent to receive information for display at a rapid rate?

Answer 50

High PRF

Question 51

What can improve the reduction of acoustic output (reduced echo amplitude)?

Answer 51

An increase of amplifier gain!

Question 52

What are the operations occurring in pulse delay?

Answer 52

Steering, scanning, transmission focusing, aperture and apodization

Question 53

What is a channel?

Answer 53

Independent signal path consisting of a transducer element, delay and possibly other electronic components

Question 54

Define gain as a ratio

Answer 54

Ratio of the amplifier output to the electric power input

Question 55

What functions accomplish reception apodization and dynamic aperture function?

Answer 55

Part of the summer (adder) process