Ch. 14 Pulsed Echo Instrumentation

Question 1

Pulsed Echo ultrasound system has two major functions:

Answer 1

1. The preparation and transmission of electrical signals to the transducer, which creates the sound beam.
2. The reception of electrical signals from the transducer, with subsequent processing into clinically meaningful images and sounds.

Question 2

The _____________ and _________________ of electrical signals to the transducer, which creates the sound beam.

Answer 2

The Preparation and transmission of electrical signals to the transducer, which creates the sound beam.

Question 3

The ___________________________ of electrical signals from the transducer, with subsequent processing into clinically meaningful images and sounds.

Answer 3

The Reception of electrical signals from the transducer, with subsequent processing into clinically meaningful images and sounds

Question 4

ultrasound systems contain these six major components:

Answer 4

1. transducer
2. pulser and beam former
3. reciever
4. display
5. storage
6. master synchronizer

Question 5

_____________________: during transmission, this transforms electrical energy into acoustic energy. During reception, it converts the returning acoustic energy into electrical energy.

Answer 5

Transducer : during transmission, this transforms electrical energy into acoustic energy. During reception, it converts the returning acoustic energy into electrical energy.

Question 6

_______________ and ______________________: creates and controls the electrical signals sent to the transducer that generate sound pulses. The ______________________ determines the amplitude, pulse repetition period, and pulse repetition frequency. While the _________________________ determines the firing delay patterns for phased array systems.

Answer 6

Pulser and Beam Former : creates and controls the electrical signals sent to the transducer that generate sound pulses. The Pulser determines the amplitude, pulse repetition period, and pulse repetition frequency. While the Beam Former determines the firing delay patterns for phased array systems.

Question 7

____________________________ : transforms the electrical signals from the transducer (produced by the reflected signal) into a form suitable for display.

Answer 7

Reciever : transforms the electrical signals from the transducer (produced by the reflected signal) into a form suitable for display.

Question 8

______________________ : presents processed data. This may be a flat screen monitor, a transparency, a spectral plot, or a variety of other formats.

Answer 8

Display : presents processed data. The display may be a flat screen monitor, a transparency, a spectral plot, or a variety of other formats.

Question 9

_____________________ : archives the ultrasound studies. Typically these devices (or media) include computer hard drives, CD, DVD, videotape, magneto-optical discs, paper printouts, photographs, and USB drives.

Answer 9

Storage : archives the ultrasound studies. Typically these devices (or media) include computer hard drives, CD, DVD, videotape, magneto-optical discs, paper printouts, photographs, and USB drives.

Question 10

_________________________________ : maintains and organizes the proper timing and interaction of the system’s components.

Answer 10

Master Synchronizer : maintains and organizes the proper timing and interaction of the system’s components.

Question 11

The ____________ creates electrical signals that excite the transducer’s PZT crystals and create sound beams

Answer 11

The Pulser creates electrical signals that excite the transducer’s PZT crystals and create sound beams

Question 12

The pulser functions during ________________________

Answer 12

The pulser functions during transmission

Question 13

True or False: Changes in pulser voltage modify the brightness of the entire image displayed on the systems screen

Answer 13

True

Question 14

Changes in the pulser voltage modify the ______ of the image.

higher voltage (output) = _______________ image

lower voltage (output) = ______________ image

Answer 14

Changes in the pulser voltage modify the brightness of the image

higher voltage (output) = brighter image

lower voltage (output) = darker image

Question 15

When the pulser voltage is low, the active element vibrates (more,less) forcefully, transmits (stronger,weaker) sound beams into the body, reflected echoes are (stronger, weaker) and the entire image is (brighter, darker)

Answer 15

less; weaker; weaker; darker

Question 16

When the pulser voltage is high, the active element vibrates (more, less) forcefully, transmits (stronger, weaker) sound beams into the body, reflected echoes are (stronger, weaker) and the entire image is (brighter, darker)

Answer 16

more; stronger; stronger; brighter

Question 17

output gain, acoustic power, pulser power, energy output, transmitter output are also known as for …

Answer 17

Pulser voltage

Question 18

Can transducer output be adjusted by the sonographer?

Answer 18

Yes

Question 19

As long as image quality is optimal, (lower, higher) pulser voltage is desirable

Answer 19

lower

Question 20

__________________ is loosely defined as a random and persistent disturbance that obscures or reduces a signals clarity.

Answer 20

Noise is loosely defined as a random and persistent disturbance that obscures or reduces a signals clarity

Question 21

A comparison of the meaningful information (signal) in an image, compared to the amount of contamination (noise)

Answer 21

Signal to Noise ratio

Question 22

When the signal-to-noise ratio is ____________, the signal is much stronger than the noise and the image is of high quality.

Answer 22

When the signal-to-noise ratio is high, the signal is much stronger than the noise and the image is of high quality.

Question 23

When the signal-to-noise ratio is ___________, the strength of the signal is closer to the strength of the noise and the image is of less quality.

Answer 23

When the signal-to-noise ratio is low, the strength of the signal is closer to the strength of the noise and the image is of less quality.

Question 24

As the sonographer increases output power, the signal-to-noise ratio _________________. (increases, decreases)

Answer 24

increases

Question 25

increasing output power is the most common way to ___________________ the signal-to-noise ratio

Answer 25

increasing output power is the most common way to *improve* the signal-to-noise ratio

Question 26

The pulser also determines the time between one voltage spike and the next known as _____________________

Answer 26

The pulser also determines the time between one voltage spike and the next known as *Pulse repetition period or PRP*

Question 27

If the pulser determines PRP, what else does it determine?

Answer 27

PRF (PRF and PRP are reciprocals)

Question 28

PRP determines the:

Answer 28

maximum imaging depth (depth of view)

Question 29

When the PRP is short, the PRF is __________ and the system spends (more,less) time listening?

Answer 29

When the PRP is short, the PRF is *high* and the system spends *less* time listening

Question 30

When the PRP is long, the PRF is _____________ and the system spends (more,less) time listening?

Answer 30

When the PRP is long, the PRF is *low* and the system spends *more* time listening

Question 31

Can a sonographer change the depth of view?

Answer 31

yes

Question 32

Shallow imaging = __________ listening, _____________ PRP, ______________ PRF and _________________ duty factor

Answer 32

Shallow imaging = *less* listening *shorter* PRP *higher* PRF *higher* duty factor

Question 33

Deep imaging = ___________ listening, _____________ PRP, _______________ PRF, ________________ duty factor

Answer 33

Deep imaging = *more* listening *longer* PRP *lower* PRF *lower* duty factor

Question 34

The __________________________ functions with array transducers during transmission and reception

Answer 34

The *Beam Former* functions with array transducers during transmission and reception

Question 35

The beam former also adjusts electrical spike voltages to reduce lobe artifacts in a process called ...

Answer 35

The beam former also adjusts electrical spike voltages to reduce lobe artifacts in a process called *Apodization*

Question 36

Modern beam formers use advanced microprocessor technology and produce signals in digital format. This device is called ______________________________

Answer 36

Digital Beam Former

Question 37

The beam former has a special "transmit-recieve" _____________ that is important during transmission and reception

Answer 37

The beam former has a special "transmit-recieve" *switch* that is important during transmission and reception

Question 38

A ____________________ is made up of a single PZT elements in the transducer, the electronics in the beam former/ pulser, and the wire that connects them

Answer 38

A *Channel* is made up of a single PZT element in the transducer, the electronics in the beam former/ pulser, and the wire that connects them

Question 39

The number of elements in an array transducer that can be excited is determined by the number of ______________________

Answer 39

The number of elements in an array transducer that can be excited is determined by the number of *channels*

Question 40

Most systems have between __ and ___ channels.

Answer 40

32-256 channels

Question 41

What are the 5 operations that must be performed in the appropriate order for the system to function properly

Answer 41

1. amplification 2. compensation 3. compression 4. demodulation 5. reject

Question 42

The first function of the receiver is ________________________, also called ...

Answer 42

The first function of the receiver is *Amplification*, also called *receiver gain*

Question 43

All electrical signals in the receiver gain are affected ________________________ by amplification

Answer 43

All electrical signals in the receiver gain are affected *identically* by amplication

Question 44

True or False: the entire image is made brighter or darker when the sonographer adjusts receiver gain

Answer 44

true

Question 45

Amplification (does, does not) improve signal-to-noise ration, since both signal and noise are amplified equally

Answer 45

does not

Question 46

True or False: Amplification alone can make an image of uniform brightness from top to bottom

Answer 46

false

Question 47

Can a sonographer alter the amplification?

Answer 47

yes

Question 48

Amplification is measured with units of ______________, which are _______________ units of measure

Answer 48

Amplification is measured with units of *decibels*, which are *relative* units of measure

Question 49

Typical values of amplification:

Answer 49

60-100 db

Question 50

The process of improving the quality of a signal before it is amplified:

Answer 50

preamplification

Question 51

Preamplification occurs ____ to the transducer and often within the transducer itself.

Answer 51

Preamplification occurs *close* to the transducer and often within the transducer itself

Question 52

The second function of the receiver is ___________________________

Answer 52

The second function of the receiver is *compensation*

Question 53

Without compensation, the ultrasound image would become progressively _________________ with increasing depth

Answer 53

Without compensation, the ultrasound image would become progressively *darker* with increasing depth

Question 54

The receiver corrects for attenuation with a process called:

Answer 54

compensation

Question 55

Compensation creates an image that is:

Answer 55

uniformly bright from top to bottom

Question 56

Can the sonographer adjust compensation?

Answer 56

yes

Question 57

Compensation is measure in units of:

Answer 57

decibels

Question 58

Compensation treats echoes differently, depending upon:

Answer 58

the depth from which they arise

Question 59

Three identical masses located in the body at depths of 2cm, 4cm, and 6cm will produce reflections with different strengths. The echo will be the ________ (strongest,weakest) from the mass of 2cm and the _________ (strongest, weakest) from the mass at 6cm

Answer 59

Three identical masses located in the body at depths of 2cm, 4cm, and 6cm will produce reflections with different strengths. The echo will be the *strongest* from the mass of 2cm and the *weakest* from the mass at 6cm

Question 60

Time gain compensation (TGC), depth gain compensation (DGC), and swepth gain are all AKA's for ..

Answer 60

Compensation

Question 61

At superficial depths, reflections undergo a small, constant amount of compensation called

Answer 61

The near gain

Question 62

The depth at which variable compensation begins is known as _____________

Answer 62

The depth at which variable compensation begins is known as *delay*

Question 63

At the depth of the _______________, reflections are maximally compensated by the ultrasound system

Answer 63

At the depth of the *knee*, reflections are maximally compensated by the ultrasound system

Question 64

The third function of the receiver is ______________________

Answer 64

The third function of the receiver is *compression*

Question 65

The ___________________ indicated the maximum amount of compensation that the receiver can provide

Answer 65

The *far gain* indicated the maximum amount of compensation that the receiver can provide

Question 66

Compression is produced twice. First, compression keeps the electrical signal within the accuracy range of the systems electronics and second, keeps an images ________________________ content within the range of detection by the human eye

Answer 66

Compression is produced twice. First, compression keeps the electrical signal within the accuracy range of the systems electronics and second, keeps an images *gray scale* content

Question 67

Humans can distinguish approximately (20, 30, 40) shades of grey.

Answer 67

20

Question 68

In the region of the _________, compensation corrects for the effects of increasing attenuation that result from increasing path length.

Answer 68

In the region of the *slope*, compensation corrects for the effects of increasing attenuation that result from increasing path length

Question 69

What allows us to visualize different tissues within 20 gray shades?

Answer 69

Compression

Question 70

Can a sonographer adjust compression?

Answer 70

yes

Question 71

Compression is expressed in units of:

Answer 71

decibels

Question 72

Log compression where small differences in _____________ signals are displayed and seen as different gray scale levels

Answer 72

Log compression where small differences in *weak* signals are displayed and seen as different gray scale levels

Question 73

Why is log compression important in clinical ultrasound?

Answer 73

most meaningful back scattered signals from biological tissues are very weak and sonographer must be able to see differences in the weak signals

Question 74

The fourth function of the receiver is ________________________

Answer 74

demodulation

Question 75

Demodulation is a process of

Answer 75

converting the voltage delivered to the receiver from one form to another

Question 76

Demodulation is a two-part process:

Answer 76

1. rectification (converts all neg voltages into pos voltages) 2. smoothing or enveloping (places a smooth line around the "bumps" and evens them out)

Question 77

Is demodulation adjustable by the sonographer?

Answer 77

No

Question 78

demodulation effect on image?

Answer 78

none; just changes the form of the electrical signal so that it is appropriate for the system's display

Question 79

The fifth function of the Receiver is:

Answer 79

Reject

Question 80

Reject allows the sonographer to control whether ________-level gray scale information within the data will appear on the displayed image *Rejection does not affect bright echoes

Answer 80

Reject allows the sonographer to control whether *low*-level gray scale information within the data will appear on the displayed image

Question 81

Can Reject be adjusted by the sonographer

Answer 81

Yes

Question 82

Reject effect on image:

Answer 82

affects low-level signals on the image, regardless of their location

Question 83

What is the difference between output power and receiver gain?

Answer 83

Output power affects image brightness by altering the strength of the sound pulse that the transducer sends to the body - increasing output power improved the signal-to-noise ratio receiver gain (amplification) alters the strength of the voltages in the receiver that the transducer created during the reception

Question 84

Patient exposure to ultrasound is affected by:

Answer 84

alterations in output power but not not by changed in amplification

Question 85

ALARA Principle (As Low As Reasonably Achievable)

Answer 85

Radiographic principle that dictates the use of every method available to reduce radiation exposure to the patient in order to minimize risks and adverse consequences of ionizing radiation

Question 86

According to the ALARA principle, if the image is too dark increase the (receiver gain, output power) first.

Answer 86

receiver gain

Question 87

According to the ALARA principle, if the image is too bright decrease the (receiver gain, output power)

Answer 87

output power